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PubMed1976

[Urinary excretion of the catecholamines adrenaline, noradrenaline and dopamine as well as the derivatives metanephrine and normetanephrine in heart disease patients].

In 20 normal persons and in 57 patients with heart diseases with functional class I-IV (according to the classification of the New York Heart Association) the 24 hour urinary excretion of the catecholamines adrenaline, noradrenaline and dopamine and of the O2-methylated degradation products metanephrine and normetanephrine was determined. The 3 catecholamines and the 2 O-methylated derivatives were measured simultaneously using chromatographic extraction and purification (Bio-Rex 70) and selective flurometric determination. The following results could be obtained: 1. The urinary excretion of noradrenaline increased with increasing severity of the heart disease. 2. In patients with severe congestive heart failure (functional class IV) in addition the adrenaline excretion in addition the adrenaline excretion increased significantly. 3. There was no relationship between the urinary excretion of dopamine and the severity of the heart disease. 4. The ratio of noradrenaline excretion to dopamine excretion increased with increasing severity of the heart disease, indicating an increased activity of dopamine-mu-hydroxylation in patients with congestive heart failure. 5. The excretion of the O-methylated degradation products metanephrine and normetanephrine in normal persons and in patients with heart diseases paralleled the excretion of the corresponding catecholamines adrenaline and noradrenaline. This indicates, that increased excretion of noradrenaline and adrenaline (Class IV) in patients with heart failure was not due to impaired catecholamine-degradation but indead to increased catecholamine-release indicating increased sympatho-adrenergic activity. These results show in addition that also in patients with heart failure O-methylation represents still the main degradation step for the inactivation of the circulating catecholamines. 6. The relationship of toal excretion of 0-methylated derivates to total excretion of adrenaline and noradrenaline, however, decreased with increasing severity of heart disease, indicating a relative impairment of O-methylation under the condition of severe congestive heart failure.

Adult↗
PubMed1999

Correlation of biliary excretion in sandwich-cultured rat hepatocytes and in vivo in rats.

The relationship between biliary excretion in sandwich-cultured rat hepatocytes and in vivo in rats was examined. The biliary excretion of seven model substrates in 96-h sandwich-cultured rat hepatocytes was determined by differential cumulative uptake of substrate in the monolayers preincubated in standard buffer (intact bile canaliculi) and Ca2+-free buffer (disrupted bile canaliculi). Biliary excretion in vivo was quantitated in bile duct-cannulated rats. The biliary excretion index of model substrates, equivalent to the percentage of retained substrate in the canalicular networks, was consistent with the percentage of the dose excreted in bile from in vivo experiments. The in vitro biliary clearance of inulin, salicylate, methotrexate, [D-pen2,5]enkephalin, and taurocholate, calculated as the ratio of the amount excreted into the bile canalicular networks and the area under the incubation medium concentration-time profile ( approximately 0, approximately 0, 4.1 +/- 1.0, 12.6 +/- 2.2, and 56. 2 +/- 6.0 ml/min/kg, respectively), correlated with their intrinsic in vivo biliary clearance (0.04, 0, 17.3, 34.4, and 116.9 ml/min/kg, respectively; r2 = 0.99). The model compound 264W94 was not excreted in bile either in vivo or in vitro. The glucuronide conjugate of 2169W94, the O-demethylated metabolite of 264W94, was excreted into bile in vitro when 2169W94, but not 264W94, was incubated with the monolayers; 2169W94 glucuronide undergoes extensive biliary excretion after administration of 264W94 or 2169W94 in vivo. Biliary excretion in long-term sandwich-cultured rat hepatocytes correlates with in vivo biliary excretion. The study of biliary excretion of metabolites in the hepatocyte monolayers requires consideration of the status of metabolic activities.

Animals↗
PubMed1992

Production, metabolism, and excretion of hydrogen in the large intestine.

Hydrogen is produced during fermentation in the large intestine and may be excreted in breath and flatus or further metabolized by the flora. However, there is little information about total H2 excretion from different substrates or the extent to which it is metabolized in the colon. We have therefore measured total H2 and methane excretion in 10 healthy subjects using a whole body calorimeter. Breath gases were measured simultaneously with total excretion in response to lactulose, pectin, and banana starch. Metabolic activities of the predominant H2 consuming anaerobes (methanogenic, sulfate reducing, and acetogenic bacteria) were measured in fecal samples. Total H2 excretion on a starch and fiber-free diet was 35 +/- 6.1 mL/24 h +/- SEM. H2 from 7.5 g, 15 g, and 22.5 g lactulose was 88.1 +/- 22.4 mL, 227.0 +/- 60.7 mL, and 321.8 +/- 79.2 mL. Four of the subjects also excreted CH4, which was 51.3 +/- 5.5 mL, 97.3 +/- 18.4 mL, and 157.5 +/- 36.3 mL for the respective lactulose doses. H2 excretion was less in methanogenic subjects (7.9 mL/g lactulose) than in nonmethanogenic (17.3 mL/g), but total H2 excreted as, hydrogen + methane, was 34.9 mL/g. H2 from pectin (20 g) was 14.1% +/- 3.2% and from starch (22.2 g) 38.6% +/- 9.2% of an equivalent lactulose dose. Sixty-five percent of total H2 and CH4 was expired in breath at total excretion rates up to 200 mL/24 h. Over this the proportion decreased to 25% with an overall average of 58%. Only subjects with CH4 excretion in vivo showed methanogenesis in feces, whereas nonmethanogenic subjects showed high sulfate-reducing activity in feces (58.7 +/- 5.6 nmol 35SO4 reduced.h-1.g-1 wet wt vs. 7.9 +/- 2.0 nmol.h-1.g-1 in methanogens). Acetogenesis rates were very low in both groups. It was concluded that H2 excretion varies with different substrates. The proportion of H2 that is exhaled in breath is higher than currently accepted and varies with total excretion rate. Substantial amounts of H2 are consumed by methanogenic and sulfate-reducing bacteria.

Adolescent↗
PubMed1991

Increased urinary zinc excretion after thermal injury.

Urinary zinc excretion normally plays a minor role in zinc homeostasis; however, urinary zinc excretion is markedly elevated after trauma or surgery, and mechanism(s) for this zinc loss are poorly defined. In this study we evaluated multiple potential mechanisms for increased urinary zinc excretion in patients with thermal injury. We documented that patients with severe thermal injury had markedly elevated urinary zinc excretion. Above 20% total body surface area burn, however, the severity of thermal injury did not correlate with urinary zinc excretion. Serum zinc concentrations were depressed on initial evaluation and gradually increased during the hospital course, whereas peak urinary zinc excretion occurred 2 to 5 weeks after injury. Thus the depression in serum zinc concentration did not temporally relate to the observed pattern of hyperzincuria. Increased urinary zinc excretion also did not temporally relate to urinary excretion of the amino acids cysteine and histidine (both of which tightly bind zinc) nor to urinary 3-methylhistidine excretion, a marker of muscle breakdown. Urinary amylase excretion, a marker of renal tubular dysfunction, did follow the pattern of urinary zinc loss to some extent, although this correlation was not perfect. Increased oral intake of zinc via zinc supplements resulted in significantly increased urinary zinc excretion. Patients receiving total parenteral nutrition (TPN) did not have significantly increased urinary zinc excretion when compared with people receiving their total nutrient intake by mouth.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Comparison of measured and predicted creatinine excretion is an unreliable index of compliance in PD patients.

OBJECTIVE: To evaluate the use of the ratio of measured to predicted creatinine excretion as an index of compliance in peritoneal dialysis (PD) patients. DESIGN: A prospective analysis. SETTING: Academic teaching hospital dialysis unit. PATIENTS: Forty-three patients on PD. MEASUREMENTS: Creatinine excretion in daily dialysate and urine collections was measured on one occasion in 10 patients and on two occasions in 33 patients, and, after adding an estimate for extrarenal creatinine degradation, was divided by predicted creatinine excretion to give a creatinine excretion ratio, which has been proposed as an index of compliance with exchanges in PD patients. Values above 1.24 have been suggested to indicate noncompliance. Lean body mass was also estimated from creatinine excretion. RESULTS: The mean creatinine excretion ratio was 1.12, and 30% of patients had a value above 1.3. Only one patient admitted noncompliance. Studies on four consecutive days of guaranteed compliance in 7 patients with high ratios showed that creatinine excretion remained constant, suggesting that the patients were high creatinine producers rather than noncompliant. Creatinine excretion was stable when measured at intervals of days, but over months it tended to change markedly in many patients. Lean body mass estimations using creatinine excretion were low in most patients. CONCLUSION: Comparison of measured and predicted creatinine excretion is not a reliable indicator of noncompliance because many compliant patients consistently excrete more creatinine than predicted. The standard formulas were not validated in dialysis patients and underestimate creatinine excretion significantly in many PD patients. Existing estimates in the literature of noncompliance, using this methodology, may not be accurate. Better methods of detecting this problem are required.

Adolescent↗
PubMed1974

Effect of bovine parathyroid hormone 1-34 fragment on renal production and excretion of adenosine 3', 5' monophosphate in man.

Biologically active bovine parathyroid hormone (b PTH) 1-34 fragment infused over one hour in normal subjects produced an immediate and sharp increase in the excreted fractions of filtered bicarbonate, sodium and potassium, followed by the return to pre-infusion levels as soon as the administration of b PTH was stopped. There was a gradual but steady increase in the excreted fraction of filtered phosphate but a decrease in the excreted fraction of filtered calcium and magnesium. The excreted fractions of these ions were still abnormal 150 minutes after the completion of PTH infusion. The urinary excretion of 3'5'-cyclic AMP increased immediately about one hundred-fold but returned rapidly to pre-infusion levels. Urinary clearance of cyclic AMP approximated glomerular filtration rate in control periods and was twenty to thirty times greater during b PTH infusion. In subjects overloaded with bicarbonate, b PTH brought about a decrease in bicarbonate T(m) and the same effects on the urinary excretion of other electrolytes. 3'5'-cyclic AMP excretion was clearly higher in control periods and reached higher levels during b PTH infusion when compared to subjects without an alkaline load. 3'5'-cyclic AMP excretion and fractional clearance were also clearly higher in subjects not given b PTH when control periods were compared to periods with bicarbonate infusion or after acetazolamide administration. During distal blockade obtained by simultaneous administration of chlorothiazide and ethacrynic acid, there was a delay in the rise of 3'5'-cyclic AMP excretion after b PTH administration. It can be concluded from these studies that the pattern of excretion of 3'5'-cyclic AMP is similar to that of bicarbonate, sodium and potassium. The increase of 3'5'-cyclic AMP excretion when urinary pH is above 7 suggests a diffusion trapping mechanism for the secretion into the lumen of this nucleotide. Distal diuretics used in distal blockade did not inhibit 3'5'-cyclic AMP production but delayed its secretion into urine.

Adenosine Monophosphate↗
PubMed1999

Effects of moxonidine and clonidine on potassium excretion in Sprague-Dawley rats.

Recently we demonstrated that clonidine and moxonidine exert specific action on fractional fluid and Na+ excretion in anaesthetised Sprague-Dawley rats. Classically, most of the diuretics used induce an increased K+ excretion, at least in part due to Na+ load in the distal tubule and exchange of Na+ by K+. Therefore, we studied the effects of moxonidine and clonidine on K+ excretion in anaesthetised Sprague-Dawley rats. Moxonidine (0.25 and 0.5 mg kg-1 body wt. i.v.) increased transiently K+ (1.0 +/- 0.3 -1.9 +/- 0.4 and 0.9 +/- 0.2 -2.9 +0.7 micromol min-1 100 g body wt.) and Na+ (1.4 +/- 1.0 -6. 9 +/- 3.1 and 0.8 +/- 0.36 -6.6 +/- 1.5 micromol min-1100 g body wt.) excretion. Clonidine (0.25 mg kg-1) caused a more pronounced increase in K+ (1.0 +/- 0.1 -2.7 +/- 0.4 micromol min-1 100 g body wt.) and Na+ (0.6 +/- 0.3 -9.5 +/- 0.4 micromol min-1 100 g body wt.) excretion, whereas the higher dose of 0.5 mg kg-1 body wt. had less effect as compared to moxonidine (K+: 0.8 +/- 0.1 -1.7 +/- 0.2 micromol min-1 100 g body wt., Na+: 0.3 +/- 0.1 -3.4 +/- 1.0 micromol min-1 100 g body wt.). The increased electrolyte excretion returned (similar to moxonidine) to baseline levels within 20 min after injection of the drugs. Antagonists such as idazoxan and yohimbine did not change K+ and Na+ excretion by their own. Both, the non-selective imidazoline/alpha2-adrenoceptor antagonist idazoxan and the pure alpha2-adrenoceptor antagonist yohimbine attenuated the moxonidin-induced effects on K+ and Na+ excretion. This could be also observed with clonidine and simultaneous injection of these two antagonists. Our results demonstrate that moxonidine and clonidine also increase renal K+ excretion in this animal model. K+and Na+ excretion show a parallel behaviour, indicating that the increased K+ excretion is mainly due to Na+ load in the tubular system.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1991

Catecholamine excretion in old age.

Catecholamine excretion was studied in two groups of nonhospitalized subjects, 60 and 80 years of age, N = 35 and 29, respectively. Urinary 24h dopamine excretion exhibited an age-related decline (p = 0.001). There was a sex difference for dopamine excretion; men had higher excretion levels (p = 0.04). Twenty-four-hour excretion of epinephrine and norepinephrine was slightly higher in 60- than in 80-year-old individuals (NS). Smoking was associated with a considerable increase in epinephrine (p = 0.001) and norepinephrine (p = 0.04) excretion. Body mass index was negatively correlated to epinephrine excretion (r = -0.27; p less than 0.05). When analyzed with a multi-way analysis of variance with analysis of covariance, significant influences of age on dopamine excretion, of creatinine clearance on dopamine and norepinephrine excretion, and of smoking on epinephrine excretion were seen. Thus, factors such as age, gender, body mass, kidney function and smoking habits considerably influence catecholamine excretion in elderly people.

Aged↗
PubMed1988

Excretion of trifluoroacetic acid as a metabolite of halothane in digestive juices.

The excretion of trifluoroacetic acid (TFAA) in bile, saliva and gastric juice of two groups of guinea pigs with bile fistulae was measured by ion-chromatography during inhalation of halothane (0.25% and 1.0%) for two hours and after inhalation of halothane. In another two groups without bile fistulae, excretion of TFAA was measured in saliva and gastric juice during and after inhalation of same concentrations of halothane.The excretion of TFAA increased with time and showed the highest concentrations in the saliva. The highest excretion rate and cumulative amounts of excreted TFAA were observed in bile. The cumulative amounts of TFAA excreted into the bile, saliva and gastric juice was 4.85 +/- 1.87 micro mol, 0.89 +/- 0.62 micro mol, 0.11 +/- 0.06 micro mol, respectively, after inhalation of 0.25% halothane and 5.36+/- 2.29 micro mol, 1.50 +/- 0.59 micro mol, 0.25 +/- 0.19 micro mol, respectively, after inhalation of 1.0% halothane. The excretion of TFAA in bile and saliva was saturated after inhalation of the higher concentration of halothane. The excretion of TFAA into the gastric juice was higher with 1.0% concentration of halothane and in animals without bile fistulae. We concluded that TFAA a metabolite of halothane is excreted not only in bile but also in saliva and gastric juice. Biotransformation of halothane in salivary glands seems very likely. A small amount of TFAA excreted in bile enters the enterohepatic circulation. The excretion of TFAA in digestive juice seems to be controlled by a rate-limiting mechanism.

Journal Article↗
PubMed1992

Increased biliary excretion of glutathione is generated by the glutathione-dependent hepatobiliary transport of antimony and bismuth.

We have recently demonstrated that the hepatobiliary transport of arsenic is glutathione-dependent and is associated with a profound increase in biliary excretion of glutathione (GSH), hepatic GSH depletion and diminished GSH conjugation (Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 41: 937-944 and Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 42: 465-468, 1991). The present studies in rats aimed to determine whether antimony and bismuth, other metalloids in group Va of the periodic table, also possess similar properties. Antimony potassium tartrate (25-100 mumol/kg, i.v.) and bismuth ammonium citrate (50-200 mumol/kg, i.v.) increased up to 50- and 4-fold, respectively, the biliary excretion of non-protein thiols (NPSH). This resulted mainly from increased hepatobiliary transport of GSH as suggested by a close parallelism in the biliary excretion of NPSH and GSH after antimony or bismuth administration. Within 2 hr, rats excreted into bile 55 and 3% of the dose of antimony (50 mumol/kg, i.v.) and bismuth (150 mumol/kg, i.v.), respectively. The time courses of the biliary excretion of these metalloids and NPSH or GSH were strikingly similar suggesting co-ordinate hepatobiliary transport of the metalloids and GSH. However, at the peak of their excretion, each molecule of antimony or bismuth resulted in a co-transport of approximately three molecules of GSH. Diethyl maleate, indocyanine green and sulfobromophthalein (BSP), which decreased biliary excretion of GSH, significantly diminished excretion of antimony and bismuth into bile indicating that hepatobiliary transport of these metalloids is GSH-dependent. Administration of antimony, but not bismuth, decreased hepatic GSH level by 30% and reduced the GSH conjugation and biliary excretion of BSP. These studies demonstrate that the hepatobiliary transport of trivalent antimony and bismuth is GSH-dependent similarly to the hepatobiliary transport of trivalent arsenic. Proportionally to their biliary excretion rates, these metalloids generate increased biliary excretion of GSH probably because they are transported from liver to bile as unstable GSH complexes. The significant loss of hepatic GSH into bile as induced by arsenic or antimony may compromise conjugation of xenobiotics with GSH.

Animals↗
PubMed1990

Extent and duration of virulent virus excretion upon challenge of pigs vaccinated with different glycoprotein-deleted Aujeszky's disease vaccines.

Different deleted Aujeszky's disease vaccines were compared for their ability to induce an immunity which suppresses virus excretion optimally upon infection. Groups of pigs were vaccinated once with attenuated deleted Aujeszky's disease vaccine (gI, gX or gp63 negative), suspended in phosphate buffered saline. Two additional groups were vaccinated with a gI deleted vaccine virus suspended in an oil-in-water emulsion. Other groups were vaccinated twice with gI deleted inactivated vaccines. The three control groups included were: pigs immune after infection, unvaccinated pigs and pigs receiving vaccine without known deletion in the envelope. Experimental challenge took place 3 or 4 weeks after the only or the last vaccination. The number of excreting pigs, the duration of excretion and the virus titers excreted, were determined for all the groups. All the pigs vaccinated with glycoprotein deletion vaccines suspended in phosphate buffered saline, excreted virus for 2 to 6 days after challenge. A 100 to 1000 fold reduction in excreted virus titers was obtained in vaccinated pigs compared to unvaccinated ones. Some vaccines suppressed virus excretion better than others, but no correlation could be made between the type of deletion (gI, gX or gp63) and the degree of reduction in virus excretion. Similar results were obtained with two applications of inactivated vaccines. The lowest number of excreting pigs, the lowest duration of excretion and the lowest titers were obtained in groups vaccinated with the attenuated vaccine suspended in an oil-in-water emulsion. No vaccine suppressed virus excretion totally.

Animals↗
PubMed1992

Effect of wheat bran on excretion of radioactively labeled estradiol-17 beta and estrone-glucuronide injected intravenously in male rats.

Urinary and fecal estrogen excretion were studied in male rats fed a non-fiber wheat starch diet (dietary fiber less than 1%; NF group; n = 4), a low-fiber wheat flour diet (dietary fiber 2%; LF group; n = 4) or a high-fiber wheat bran diet (dietary fiber 11.6%; HF group; n = 3). Short-term effects of the experimental diet on estrogen excretion were studied after i.v. injection of 5 microCi (0.185 MBq) of [14C]estradiol-17 beta (E2) into the tail vein of the rats fed the diets for 2 days. After 3 weeks on the experimental diets, the long-term effects were studied after injection of 5 microCi of [14C]E2 and 10 microCi of [3H]estrone-3-glucuronide (E1-gluc). The diet was found to affect estrogen excretion. The short-term effect indicated that rats fed the HF diet excreted a relatively large amount of labeled compounds in the feces during the first day after injection, while rats fed the NF or the LF diets excreted about half that amount over the same period. On the other hand, urinary excretion of labeled compounds was significantly higher in the NF and LF rats. The long-term effect resulted in steeper slopes (P less than 0.05) of the fecal excretion profiles of rats fed the HF diet as compared with rats fed the NF and LF diets, indicating an accelerated fecal excretion of labeled compounds in the HF rats. The kinetic profiles of 14C and 3H radioactivity in blood plasma indicated a fast decrease (t1/2 of less than 2 min) for both [14C]E2 and [3H]E1-gluc. It was concluded that, owing to the short-term effect of wheat bran intake, during the first 24 h after i.v. administration relatively large amounts of radioactively labeled compounds are excreted in feces of rats fed the HF diet. In contrast, excretion is lower in urine of these rats. When the microflora is adapted to the experimental diet the wheat bran diet still results in an accelerated fecal excretion of labeled compounds, which might be attributed to an interruption of the enterohepatic circulation of estrogens. This might result in lowered plasma and/or tissue estrogen levels and hence a decreased exposure of estrogen-sensitive tissue to estrogens, which might decrease risk on mammary (breast) cancer development.

Animals↗
PubMedDate not supplied

Cytomegalovirus excretion in children attending day-care centers.

BACKGROUND: Healthy children attending day-care centers (DCC) may excrete cytomegalovirus (CMV) frequently. Mothers of children excreting CMV are at higher risk for acquiring this infection than mothers of children not excreting CMV. Despite the increased attendance to DCC by children there is a lack of information regarding CMV infection in Mexico. METHODS: Prospective determination of CMV excretion in saliva of children attending public and private DCC. Three saliva samples were collected during a 2-month follow-up period from participating children and the presence of CMV was determined by viral culture. Demographic features of children and DCC type were taken into account when comparing children with and without CMV excretion. RESULTS: One hundred fifty-two children participated in the study (84 from public and 68 from private DCC). Overall, 17 (11.2%) children excreted CMV during the study period. Excretion rates varied between DCC from 3.1 to 31.3%. Children from private DCC were as likely to excrete CMV as children from public DCC. There were no demographic or clinical features of children associated with viral excretion. CONCLUSIONS: CMV was excreted on an average of 11.2% children attending DCC. The type of DCC or other demographic features were not associated with the likelihood of CMV excretion. CMV seronegative mothers of children who attend DCC need to be aware of the possibility of CMV acquisition and transmission in DCC.

Child↗
PubMed2006

Low serum dehydroepiandrosterone sulfate concentration is a predictor for deterioration of urinary albumin excretion in male patients with type 2 diabetes.

We recently found that serum dehydroepiandrosterone sulfate (DHEA-S) concentration correlated inversely with the degree of urinary albumin excretion in a cross-sectional study. We therefore performed an observational study to investigate the relationship between serum DHEA-S concentrations and changes in urinary albumin excretion in male patients with type 2 diabetes to answer the question as to whether DHEA is a causal rather than simply coincidental intermediate linking urinary albumin excretion to cardiovascular disease (CVD). The relationship between serum DHEA-S concentration and changes in urinary albumin excretion was investigated in 207 consecutive male patients with type 2 diabetes. Baseline serum DHEA-S concentration and urinary albumin excretion were measured in 2003. After 12 months, urinary albumin excretion was measured and any changes in urinary albumin excretion were calculated. Patients were divided into tertiles according to DHEA-S concentration. Greater changes in urinary albumin excretion were seen in patients with low DHEA-S concentration (29.6+/-7.6mg/g creatinine) than in patients with high DHEA-S concentration (5.1+/-3.6mg/g creatinine, P=0.0091). An inverse correlation was observed between serum DHEA-S concentration and changes in urinary albumin excretion (r=-0.193, P=0.0052). Multiple regression analysis demonstrated that HbA1c (beta=0.241, P=0.0009), and serum DHEA-S concentration (beta=-0.195, P=0.0054) were independent determinants of changes in urinary albumin excretion. In conclusion, serum DHEA-S concentration was inversely correlated with changes in urinary albumin excretion, which may indicate causality in the increased CVD mortality in male patients with type 2 diabetes and low DHEA-S concentration.

Aged↗
PubMed2000

Ammonium and phosphate excretion in three common echinoderms from Philippine coral reefs.

The ammonium and phosphate excretion and oxygen consumption of three species of echinoderms (Tripneustes gratilla, Protoreaster nodosus and Ophiorachna incrassata) commonly encountered in Philippine coral reefs were investigated in relation to time of day (i.e. daytime between 10:00 and 12:00 h vs. nighttime between 22:00 and 24:00 h) and their recent feeding history (i.e. recently-collected vs. short-term starvation for 3+/-1 days). The experiment used whole organism incubations and followed a nested hierarchical design. Ammonium excretion rates were 1447+/-310 nmolg(-1) DWh(-1) (mean+/-S.E., n=24) for T. gratilla, 361+/-33 for O. incrassata and 492+/-38 for P. nodosus. Ammonium excretion differed significantly among species, time of incubation and recent feeding history. Interaction between species and recent feeding history was also significant. The organisms excreted more ammonium during daytime except for starved specimens of O. incrassata. In addition, animals that were starved in the laboratory for a few days had a tendency to excrete more ammonium than recently-collected specimens. Phosphate excretion rates were 25+/-13 nmolg(-1) DWh(-1) for T. gratilla, 10+/-2 for O. incrassata and 4+/-1 for P. nodosus. There were no significant differences in phosphate excretion among the three species of echinoderms, their recent feeding history and time of day. Oxygen consumption rates were 286+/-24 µg O(2)g(-1) DWh(-1) for T. gratilla, 64+/-3 for O. incrassata and 54+/-3 for P. nodosus. Oxygen consumption differed significantly among species and recent feeding history but differed only slightly with time of incubation. There was a significant correlation between oxygen consumption and ammonium excretion (r=0.48, P=0.018), and between oxygen consumption and phosphate excretion (r=0.41, P=0.047) for T. gratilla. The nutrient excretion by tropical echinoderms is another pathway by which inorganic nutrients are regenerated in coral reef communities. However, the quantity of nutrients excreted is dependent on the species of echinoderms, their nutritional status and time of day.

Journal Article↗
PubMed1996

Modulation of hepatic content and biliary excretion of P-glycoproteins in hepatocellular and obstructive cholestasis in the rat.

BACKGROUND/AIMS: Release into bile of canalicular membrane enzymes, such as alkaline phosphatase and gamma-glutamyl transpeptidase, is significantly increased in rats subjected to experimental models of hepatocellular or obstructive cholestasis. This effect appears to be related to a greater susceptibility of these membrane intrinsic proteins to the solubilizing effects of secreted bile acids. It is not known whether canalicular membrane transport proteins, such as P-glycoprotein isoforms, involved in ATP-dependent xenobiotic biliary excretion and phospholipid secretion, are excreted into bile and whether this process is modified in cholestasis. The aims of this work have been to investigate in the rat: a) whether P-glycoproteins are normally excreted into bile, b) whether their excretion is modified in two experimental models of cholestasis, i.e., hepatocellular cholestasis induced by ethynylestradiol and obstructive cholestasis, and c) whether observed changes correlate with bile acid and phospholipid secretion and enzyme release into bile and with relative P-glycoprotein content in hepatic tissue and isolated and purified canalicular membranes. METHODS: P-glycoproteins in bile and hepatic tissue were identified and quantitated by Western-blotting and immunohistochemistry using the C219 MAb. Changes in total mdr mRNA were analyzed by Northern-blotting. RESULTS: Like canalicular membrane enzymes, P-glycoproteins are normally excreted into bile. Ethynylestradiol-induced cholestasis was associated with a 4.9-fold increase in P-glycoprotein excretion compared with controls while, in contrast, the excretion of the carrier decreased markedly in obstructive cholestasis to 2% of control values. P-glycoprotein excretion per nmol of secreted bile acids increased 4.4-fold in ethynylestradiol-induced cholestasis but decreased to 2% of control values in obstructive cholestasis. Total mdr mRNA levels in hepatic tissue were markedly increased (3.4-fold) in rats subjected to obstructive cholestasis and moderately increased (1.6-fold) in the ethynylestradiol group, compared with controls. P-glycoprotein content in isolated canalicular membranes was slightly decreased by 15% in ethynylestradiol-induced cholestasis, while it increased 4.7-fold in obstructive cholestasis. Immunohistochemistry of rat livers showed that P-glycoprotein reaction at the canalicular domain of hepatocytes at acinar zone 1 was decreased in ethynylestradiol-treated rats and markedly increased in obstructive cholestasis. CONCLUSIONS: Ethynylestradiol-induced cholestasis is associated with increased P-glycoprotein biliary excretion and decreased hepatic content. In contrast, obstructive cholestasis results in decreased P-glycoprotein biliary excretion and increased hepatic content. These results suggest that biliary P-glycoprotein excretion might be a modulating factor in canalicular membrane P-glycoprotein content. Increased P-glycoprotein release into bile in ethynylestradiol-treated rats is apparently not a consequence of cholestasis, but it might be a primary event and play a pathogenetic role in ethynylestradiol-induced cholestasis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Urinary equol excretion in relation to 2-hydroxyestrone and 16alpha-hydroxyestrone concentrations: an observational study of young to middle-aged women.

Approximately one-third to one-half of individuals harbor the colonic bacteria that are capable of metabolizing the soy isoflavone daidzein to equol. Results of prior studies suggest beneficial effects of producing equol in relation to breast cancer risk, potentially through effects on endogenous hormones. High urinary excretion of 2-hydroxyestrone (2-OH E(1)) relative to 16alpha-hydroxyestrone (16alpha-OH E(1)) has been associated with a reduced risk of breast cancer. In this pilot study we examined associations between urinary excretion of equol and 2-OH E(1), 16alpha-OH E(1), and their ratio, and investigated whether excretion of these estrogen metabolites differed between two samples collected 48h apart. Isoflavones (genistein, daidzein, O-desmethylangolensin (ODMA), and equol) were measured in two overnight urines from 126 women. Excretion of 2-OH E(1) and 16alpha-OH E(1) were measured in the first overnight urine from all 126 women and in the second overnight urine from 30 of these women; there were no significant differences between samples collected 48h apart in excretion of 2-OH E(1) or 16alpha-OH E(1) (P=0.75 and 0.17, respectively). Among all women, correlations between total isoflavone excretion (sum of genistein, daidzein, ODMA, and equol) and estrogen metabolites were non-significant (P>0.05). Among women with detectable levels of equol, total isoflavone excretion was significantly positively correlated with 16alpha-OH E(1) (r=0.32, P=0.02), but was not correlated with 2-OH E(1) or 2-OH E(1):16alpha-OH E(1) ratio (r=0.21, P=0.14, and r=-0.05, P=0.70, respectively). Equol excretion (adjusted for other isoflavone excretion) was significantly positively correlated with 2-OH E(1):16alpha-OH E(1) ratio (r=0.38, P=0.005), but was not correlated with 2-OH E(1) or 16alpha-OH E(1) (r=0.15, P=0.29, and r=-0.17, P=0.24, respectively). The finding that equol excretion, but not total isoflavone excretion, correlated positively with the 2-OH E(1):16alpha-OH E(1) ratio suggests that the colonic bacterial profile associated with equol production may be involved in estrogen metabolism, and may therefore possibly influence breast cancer risk.

Adult↗
PubMed1972

Species variations in the threshold molecular-weight factor for the biliary excretion of organic anions.

1. The excretion in the bile and urine after intravenous injection of 16 organic anions having molecular weights between 355 and 752 was studied in female rats, guinea pigs and rabbits. 2. These compounds were mostly excreted unchanged, except for three of them, which were metabolized to a slight extent (<7% of dose). 3. The rat excreted all the compounds extensively (22-90% of dose) in the bile. 4. In guinea pigs four of the compounds with mol.wt. 355-403 were excreted in the bile to the extent of 7-16% of the dose, four with mol.wt. 407-465 to the extent of 25-44% and eight compounds with mol.wt. 479-752 to the extent of 44-100%. 5. In rabbits four compounds with mol.wt. 355-465 were excreted in the bile to the extent of 1-8% of the dose, two compounds with mol.wt. 479 and 495 to the extent of 24 and 22%, and six compounds with mol.wt. 505-752 to the extent of 31-94%. 6. These results, together with those of other investigations from this laboratory, are discussed and the conclusion is reached that there is a threshold molecular weight for appreciable biliary excretion (i.e. more than 10% of dose) of anions, which varies with species: about 325+/-50 for the rat, 400+/-50 for the guinea pig and 475+/-50 for the rabbit. 7. Anions with molecular weights greater than about 500 are extensively excreted in the bile of all three species. 8. That proportion of the dose of these compounds which is not excreted in the bile is excreted in the urine, and in the three species, bile and urine are complementary excretory pathways, urinary excretion being greatest for the compounds of lowest molecular weight and tending to decrease with increasing molecular weight. 9. Some implications of this interspecies variation in the molecular-weight requirement for extensive biliary excretion are discussed.

Animals↗