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PubMed1983

The effect of mass on the gastrointestinal absorption of plutonium and neptunium.

Absorption and retention of plutonium were determined in mice after intragastric administration of either 6 X 10(-4) or 1.5 mg/kg in bicarbonate, citrate, or nitrate media. At the higher concentration, absorption of the citrate was greater than that of the nitrate; at the lower concentration, chemical form was not an important factor in absorption. Concentration and chemical form had much less influence on absorption by the neonatal (versus the adult) rat. The transfer factor (f1) for neonates was between one and two orders of magnitude higher than for adults. Absorption and retention of neptunium were determined in rats and/or mice after intragastric administration at doses ranging from 2.2 X 10(-7) to 43 mg/kg in nitrate solutions of pH 1.5. At the higher concentrations, absorption was 1.5 to 2.7%. For lower concentrations, absorption was 25 to 65 times less. In contrast to results obtained in adult animals, absorption of neptunium by neonates decreased with increasing dose. The data obtained in adult animals suggest that the f1 factor recommended by the ICRP for plutonium should be increased by a factor of 10, but the neptunium f1 factor, in contrast, should be decreased by a factor of 10.

Animals↗
PubMed1981

D(+)-xylose absorption test in the horse. A clinical study.

25 horses were subjected to the D(+)-xylose absorption test. 1 gram of D(+)-xylose/kg bw. was administered orally. Based upon the shape of the absorption curves the 25 patients were divided into four groups. Group 1 11 patients with a normal absorption curve (Figure 3) Group 2 5 patients with a flat absorption curve (Figure 4) Group 3 3 patients with a flat absorption curve (Figure 5) Group 4 7 patients with an intermediary type of absorption curve (Figure 6). Administration of sodium chloride in equimolar concentrations did not improve the absorption of D(+)-xylose. 73 per cent of the horses with actual or recent signs of gastrointestinal disease revealed a decreased absorption of D(+)-xylose. It is concluded that the test is valuable in the evaluation of intestinal function in the horse.

Animals↗
PubMed1980

Cholesterol absorption in man: effect of administration of clofibrate and/or cholestyramine.

Cholesterol absorption measurements were carried out in a free-living out-patient population by a plasma isotope-ratio method previously validated for in-patients (Samuel, P., J. R. Crouse and E. H. Ahrens, Jr., 1978. J. Lipid Res. 19: 82-93). To test the reproducibility of the method in out-patients, 18 patients were tested twice: the mean intra-assay variability was +/- 6.0%. The method was then applied in 150 hyperlipidemic male out-patients, ingesting a standardized diet containing 250mg cholesterol per day, who had been randomized into four different drug-treatment groups: 1) no medication, 2) clofibrate, (2g/day), 3) cholestyramine (16g/day), or 4) both clofibrate and cholestyramine. Cholesterol absorption (as percent of the oral dose) was increased in patients receiving cholestyramine (P < 0.02) and decreased in those receiving clofibrate (P < 0.02); the group on the combined medication had the same pecent absorption as the control group. In twelve patients receiving cholestyramine, a second test of cholesterol absorption was performed 30 min after each patient had received 8g of cholestyramine. The pre-test administration of cholestyramine caused a 38% decrease in cholesterol absorption (P < 0.001), compared to results obtained when medication was withheld prior to testing. These results demonstrate that the isotope-ratio method of measuring cholesterol absorption is a reproducible procedure applicable to a free-living out-patient population, and that the hypolipidemic drugs, clofibrate and cholestyramine, significantly affect cholesterol absorption in man. The data also show that the results of measurements of cholesterol absorption can be profoundly altered by the type and timing of medication in relationship to the test meal of labeled cholesterol.

Absorption↗
PubMed1995

Gastrointestinal absorption of peptide drug: quantitative evaluation of the degradation and the permeation of metkephamid in rat small intestine.

The intestinal absorption of metkephamid (MKA), an analog of natural [Met]enkephalin, was investigated by means of vascular perfusion of the rat small intestine. Most of the MKA administered to the jejunal loop was degraded in the lumen by enzymatic hydrolysis, whereas only 0.3 to 1.2% of it was absorbed into the vascular flow. This means that enzymatic degradation is a major barrier against the intestinal absorption of MKA. The absorption of MKA was divided into two steps, degradation and permeation, and is expressed as clearance from the intestine. The degradation clearance (CLd) of MKA was 60- to 200-fold higher than the permeation clearance (CLp), indicating the rapid hydrolysis of MKA before absorption. The absorbed fraction of MKA increased with increasing luminal MKA concentration, mainly due to an increase in CLp rather than a decrease in CLd. MKA was degraded not only before absorption but also during permeation across the intestinal epithelium. Three kinds of enzyme inhibitors were co-administered with MKA into the intestinal loop. Puromycin, an aminopeptidase M inhibitor, markedly enhanced MKA absorption by both decreasing CLd and increasing CLp, indicating the predominant role of this enzyme in MKA degradation. Bestatin, another aminopeptidase M inhibitor, also effectively suppressed the degradation of MKA before absorption, whereas it only slightly increased CLp. It was further found that bestatin was less effective in inhibiting MKA hydrolysis during permeation. Thiorphan, an enkephalinase inhibitor, had no effect on MKA absorption.

Amino Acid Sequence↗
PubMed1995

Gastrointestinal absorption of inorganic arsenic (V): The effect of concentration and interactions with phosphate and dichromate.

The absorption of inorganic pentavalent arsenic (As) by the rat small intestine was investigated using 2 different procedures: In vivo determination of overall extent of gastrointestinal absorption; and an intestinal perfusion technique. The aim was to determine the effect of concentration and the interaction with phosphate and dichromate anions on gastrointestinal absorption of As to understand the mechanism of As absorption at intestinal level. The results indicate there is a direct relationship, although not proportional, between the received dose and the absorbed amount of As. Intestinal absorption of As appears carried out by a saturable transport process. The phosphate produces a pronounced decrease in the intestinal absorption of As due to the fact that phosphate and As can share the same transport mechanism which is an active secondary carrier-mediated system depending on Na+ and H+ gradient. Addition of dichromate to perfusion buffers significantly (p > 0.05) increased As absorption. Several hypothesis may explain this fact: Dichromate produces pH modifications at the intracellular level, providing an adequate H(+)-gradient for As absorption; dichromate exerts a caustic effect, which damages the intestinal wall at the microvilli level. This allows free diffusion of As through the resulting openings.

Animals↗
PubMed1995

[Quantitative study of a SEM image processing system on the absorptive mesothelium of the diaphragmatic peritoneum].

SEM and a medical image processing system attached to SEM were used to study the peritoneal mesothelium on mice diaphragm. The absorptive mesothelium was first reported owing to its function and morphology. The absorptivity of diaphragmatic peritoneum was surveyed by the measurement of the area of the absorptive mesothelium. The arrangement of the absorptive mesothelium on diaphragmatic peritoneum was block-like with abnormal distribution, and the maximum and minimum areas of the block were 1153 microns 2 and 66 microns 2. But the absorptive mesothelium on left and right half diaphragm were normally distributed. The average areas of the absorptive mesothelium on all diaphragm, left half diaphragm and right half diaphragm were 432.6 microns 2, 270.5 microns 2 and 512.0 microns 2 respectively. The distributive law of the absorptive mesothelium was costal portion > sternum portion > vertebral column portion. The average absorptivity of all diaphragmatic peritoneum was 29.2%, but that of left and right half diaphragmatic peritoneum were 17.4% and 32.9% respectively.

Absorption↗
PubMed1996

Percutaneous absorption of hydrocortisone and testosterone on the vulva and forearm: effect of the menopause and site.

The percutaneous absorption of hydrocortisone and testosterone was studied following their application to the vulvar and ventral forearm regions of pre- and post-menopausal women. Percutaneous absorption of hydrocortisone was significantly greater in vulvar skin than forearm skin in both pre- and post-menopausal women (P < 0.05, respectively), whereas the percutaneous absorption of testosterone was significantly increased (P < 0.01) on the vulva compared with the arm only in post-menopausal women. The effect of age on the percutaneous absorption of hydrocortisone and testosterone was evaluated by using the menopause as a biological chronometric end point. It is a common misconception that older skin has a diminished barrier capacity, and that percutaneous absorption is therefore greater. Our studies showed that absorption of hydrocortisone vulval skin of pre-menopausal women was significantly greater (P < 0.01) than in post-menopausal women. The ventral forearm skin of pre-menopausal women tended to show increased absorption compared with post-menopausal women, but statistical significance was not reached. No significant differences (P > 0.05) in the percutaneous absorption of testosterone in vulval or forearm skin were observed between the two age groups.

Administration, Topical↗
PubMed1996

Adaptation of cholesterol absorption after proximal resection of porcine small intestine.

Cholesterol absorption occurs primarily in the upper small intestine. Our aim was to assess absorption of cholesterol during ileal adaptation after proximal small intestinal resection. In vivo absorption and elimination of cholesterol, plasma cholesterol, cholesterol precursors, and plant sterols were related to intestinal morphology and transit 4 (n = 5), 8 (n = 5), and 14 (n = 5) weeks after a 75% proximal resection of porcine small intestine, and compared to preoperative (n = 5) and transected (n = 5) control animals. Fractional cholesterol absorption, the daily amount of cholesterol absorbed, plasma cholesterol, and plant sterol to cholesterol proportions were significantly (P < 0.05 or less) decreased, whereas fecal loss of cholesterol as neutral steroids, less so as bile acids, plasma cholesterol precursor proportions, and ileal mass and villus height were significantly increased (P < 0.05 or less) after 8 weeks of the resection. Cholesterol absorption efficiency, decreased by the resection, was gradually increased from 5.4 +/- 2.2 to 26.9 +/- 3.9% during the 14 postoperative weeks (P < 0.0001) simultaneously with a 46% increase in villus height compared with transection (P < 0.0001), but absorption remained still below control levels (80.4 +/- 2.5%, P < 0.0001). In resected and control animals, villus height correlated positively with cholesterol absorption efficiency (r = 0.85, P < 0.0001; r = 0.76, P = 0.01) and plasma plant sterol proportions (r = 0.94-0.95, P < 0.0001; r = 0.78-0.85, P < 0.008), respectively. In conclusion, after massive proximal small bowel resection, adaptation of intestinal cholesterol absorption efficiency occurs in the distal ileum closely parlleling villus hypertrophy.

Adaptation, Physiological↗
PubMed1977

Puromycin inhibition of cholesterol absorption in the rat.

The effect of puromycin on the intestinal absorption of cholesterol has been studied in rats with indwelling catheters in the left thoracic lymphatic duct. Puromycin administration to female rats produced a marked depression of cholesterol absorption under conditions where the absorption of simultaneously administered fatty acid was also dramatically inhibited. The same treatment of male rats also produced a significant depression in cholesterol absorption, but was without effect on absorption of the fatty acid. Despite the depressions of lipid absorption in puromycin-treated animals, there was no accumlation of either cholesterol or fatty acid in the intestinal mucosa of either sex. Actinomycin D treatment of fasting male and female rats, receiving constant infusions of saline, had no effect on the rate of lymph production. This suggest that altered lymph production was not responsible for the depressed lipid absorption observed in fed animals treated with protein synthesis inhibitors. The selective inhibition of cholesterol absorption in male rats also precludes the possibility that the major effect of the inhibitor is on delayed gastric emptying.

Animals↗
PubMed1998

Computer simulation of microscopic cerebral air emboli absorption during cardiac surgery.

Microscopic cerebral arterial air emboli (MCAAE) cause neurologic injury during cardiac surgery. We used a mathematical model of gas absorption to gain a preliminary assessment of what physical or physiologic parameters affect MCAAE absorption in the setting of cardiac surgery with its unique set of normal values. Simulated MCAAE of radii 50 and 200 microns have absorption times of 2 and 32 min, respectively. Predicted absorption times depend dramatically on PaN2. MCAAE are predicted to be absorbed twice as quickly at a PaN2 of 0 vs. 380 mmHg (FiO2 approximately equal to 0.50). Moderate hypothermia (27 degrees C) is predicted to cause only small decreases in absorption time. Changes in cerebral blood flow (for example, as affected by hemoglobin concentration, PaCO2, PaO2, collateral circulation, anesthetics, or cerebral metabolism) probably have only small effects on absorption time. Intravascular perfluorocarbons are predicted to cause small-to-moderate decreases in absorption time. In conclusion, there is probably only one important determinant of MCAAE absorption time during normothermic or moderately hypothermic CPB: arterial nitrogen partial pressure.

Absorption↗
PubMed1976

Regional ileitis (Crohn's disease). I. Kinetics of bile acid absorption in the perfused ileum.

Bile acid absorption was studied by steady state perfusion technique in the ileum of 11 patients with regional ileitis (Crohn's disease). By computerizing absorption kinetics the presence of an active transport of glycochenodeoxycholic acid (GCDC) was rendered probable by finding a saturable transport system and a competitive absorption between conjugated bile acids. At the time of investigation 5 patients had no diarrhoea, whereas 6 patients had diarrhoea as defined from the amount of faecal output. In the former group the faecal bile acid excretion was low, the ileal absorption of GCDC high, and judged from the xylose absorption the ileal absorption surface large compared to the latter group, in which the faecal bile acid excretion was high, the ileal absorption of GCDC low, and the ileal absorptive surface small. It is concluded that malabsorption of bile acids in the ileum may be of significant physiological importance in the pathogenesis of diarrhoea in patients with regional ileitis.

Adult↗
PubMed1998

[Absorptive pattern of individual fatty acids and total fat in full term babies. Its stability in the absence of lactose].

OBJECTIVE: Lactose absence implies a decrease in calcium absorption. If not absorbed, calcium soaps can be produced with the intestinal fatty acids. Absorption and retention of total fat, individual fatty acids, calcium, magnesium and phosphate have been compared between two groups of children, one fed with lactose free formula and higher levels of calcium (FSL) and the other with standard starting formula (FI). None of them had additional arachidonic or docosahexaenoic acids. PATIENTS AND METHODS: A randomized prospective study was made on 19 term newborn babies by means of metabolic balance measurement during an 8 day period (four days of a stabilization period on the formula, 3 days of the balance period and the final day for feces collection). Both groups were selected following the same criteria for gestational age, balance age, and weight and length at both time periods. Aliquos from the formula were collected daily, as well as all feces and urine during the balance period. Calcium and magnesium quantification of the corresponding ashed products was performed by means of atomic absorption, while Pi was with a colorimetric assay. Total fat was extracted by organic solvents and quantified by gravimetry. Lipid phase fatty acids were methylated, extracted and quantified by means of gas chromatography with a detector of flame ionization. RESULTS: Total fat content and the percentages of each fatty acid did not differ, only calcium concentration in FSL was slightly higher (64.9 +/- 6.9 vs 58.9 +/- 7.0 mg/100 g). No differences were found between groups in relation to ingestion, excretion and retention. The percentages of calcium and total fat retention, however, were slightly superior in the FI in relation to the FSL group. Ca: 68 +/- 22 mg/kg/d, 49 +/- 14% vs 56 +/- 23 mg/kg/d, 48 +/- 17% and total fat: 6.6 +/- 1.2 g/kg/d, 92 +/- 8% vs 6.8 +/- 1.5 g/kg/d, 90 +/- 9%. Absorption of MC fatty acids was 99% for C8. Linoleic and alfalinolenic acid showed an absorption of around 90% despite the big differences in their intake (10/1). Net retention of linoleic acid was 933 +/- 168 mg/kg/d (FI) and 963 +/- 190 mg/kg/d (FSL) and the amount of alpha-linolenic acid was 95 +/- 16 (FI) and 100 +/- 22 mg/kg/d (FSL). No correlation could be found between the amount of excreted calcium and the total amount of fat in feces or with any of the fatty acids studied. This was true for each group studied separately or when considered as a single group. CONCLUSIONS: The absorptive pattern of fatty acids in full term babies, when quantified did not show any conspicous alterations in relation to the accepted values of other ages. The absence of lactose (FSL) in a formula does not make any change in the absorption of total fat and the individual fatty acids when compared to lactose containing formula (FI), when these are present in the same proportions. Supplemented calcium in the formula without lactose could compensate for its lower absorbtion. The absorptive pattern of fatty acid in full term babies did not show any conspicuos alterations in relationship to the accepted values of other ages.

Absorption↗
PubMed1999

Percent cholesterol absorption in normal women and men quantified with dual stable isotopic tracers and negative ion mass spectrometry.

Percent cholesterol absorption was measured in 94 normal subjects aged 17- 80 years while consuming diets generally low in cholesterol (mean intake = 226 +/- 126 mg/day). A new dual stable isotope method was used where a cholesterol tracer containing 6 extra mass units was given intravenously and another tracer with 5 extra mass units was given orally during a standard test meal. The ratio of tracers in plasma was determined by negative ion mass spectrometry of pentafluorobenzoyl sterol esters. Absorption values ranged widely from 29.0% to 80.1% with mean 56.2 +/- 12.1 (SD) %. Cholesterol absorption was significantly increased in African-Americans (63.4 +/- 11.8% vs. 55.1 +/- 11.9%, P = 0.027) but was similar for women (53.3 +/- 11.9%) and men (57.6 +/- 12.1%). It was not related to plasma lipoproteins, age, apoE3/E3 or E3/E4 genotype, or chronic dietary intake of energy, fat, or cholesterol quantitated from 7- day food records. However, dietary cholesterol intake was positively related to plasma cholesterol (P = 0.036) and triglycerides (P = 0.026). The milligram amount of dietary cholesterol absorbed (but not percent absorption) was positively correlated with fasting plasma insulin (r = 0.525, P < 0.0001), C-peptide (r = 0.367, P = 0.0003) and glucagon (r = 0.421, P < 0.0001) independent of gender, body fat percent and age.The efficiency of intestinal cholesterol absorption and the milligram amount of dietary cholesterol absorbed were not related to plasma cholesterol or LDL cholesterol in individuals consuming a low-cholesterol low-fat diet. The dominant factor determining dietary cholesterol absorption was intake rather than absorption efficiency. Dietary cholesterol and fat were strongly and independently related to hormonal measures of insulin resistance.-Bosner, M. S., L. G. Lange, W. F. Stenson, and R. E. Ostlund, Jr. Percent cholesterol absorption in normal women and men quantified with dual stable isotopic tracers and negative ion mass spectrometry.

Adult↗
PubMed1983

The relationship between capacity for absorption and chronic headache patients' response to relaxation and biofeedback treatment.

A sample of 49 chronic headache patients (35 vascular and 14 tension) was separated according to capacity for absorption (as measured by Tellegen & Atkinson's 1974 scale) into groups high in absorption and groups low in absorption, with patients in the middle range being excluded. Absorption capacity was found to affect response to treatment in complex ways. Vascular headache patients high in absorption were significantly improved following relaxation training, but not after biofeedback training. Vascular headache patients low in absorption were significantly improved after biofeedback training. Tension headache patients low in absorption did not respond significantly to either form of treatment, while those high in absorption responded significantly to biofeedback training. Reasons for these differences in response to treatment were discussed.

Attention↗
PubMed1988

Analysis of the near-ultraviolet absorption and circular dichroic spectra of parsley plastocyanin for the effects of pH and copper center conformation changes.

The absorption and circular dichroic (CD) spectra of parsley plastocyanin (PC) were measured in order to determine the effects of changes in primary amino acid sequence on both the copper center and protein components of the PC molecule. The near-ultraviolet (uv) absorption and CD spectra of parsley PC were found to be qualitatively similar to those of spinach, poplar, and lettuce PC, except for the near-uv CD spectrum of the reduced form at low pH (ca. pH 5.0). The CD spectrum of reduced parsley PC in the 250-265 nm wavelength region changes from positive to negative ellipticity upon reduction of pH, and is characterized by a pKa value of 5.7. This pKa value is the same as that for the protonation of the histidine 87 copper ligand, observed by NMR, and the change in conformation of the copper center. Similar processes are believed to occur in the other PC species at lower pH values. Thus, the pH-dependent perturbations of the near-uv CD spectra of reduced PC are interpreted as due to transitions in the reduced copper center. The increase in the near-uv absorption spectrum of reduced PC can be divided into pH-independent and pH-dependent portions. The pH-independent portion resembles the absorption spectrum of tetrahedral Cu(I) metallothionein, suggesting the presence of Cu(I)-Cys 84 and/or Cu(I)-Met 92 charge transfer transitions in the near-uv absorption spectra of reduced PC. The pH dependence of the absorption spectrum changes and the pH difference absorption spectrum indicate that tyrosine residues may contribute to at least a part of the pH-dependent portion of the absorption increase of reduced PC.

Chlorophyll↗
PubMed1990

Literature-derived absorption coefficients for 39 chemicals via oral and inhalation routes of exposure.

Absorption refers to the amount of a chemical or substance that is able to cross biological membranes and be taken up by the blood for subsequent distribution to target tissues. The term absorption coefficient, as used here, is a numerical descriptor characterizing that fractional uptake by the blood and represents an approximation of the biological "dose" ultimately responsible for toxicity or other effects following exposure or chemical administration. Regulatory agencies utilize absorption coefficients in deriving acceptable daily intake values and health advisory indices, as well as in quantifying radiological risk. However, absorption coefficients do not exist for many chemicals due to a paucity of appropriate toxicological data. As a result, regulatory policy must often provide default options that assume, for example, 100% absorption by all routes to permit evaluation of "data-gap" chemicals. This paper attempts to improve the situation by providing a discrete source of route-specific absorption coefficients that are based on experimental data reported in the open literature. The estimates presented here are the result of an extensive investigation of three data bases (TOXLINE, HSDB, and CIS), many agency documents, and nearly 200 articles from 30 scientific journals. Acknowledging that absorption efficiency varies with dietary status, age, and several other situation-specific factors, the estimates presented here are intended to reflect absorption by the average adult human.

Administration, Inhalation↗
PubMed1993

Picosecond time-resolved absorption and fluorescence dynamics in the artificial bacteriorhodopsin pigment BR6.11.

The picosecond molecular dynamics in an artificial bacteriorhodopsin (BR) pigment containing a structurally modified all-trans retinal chromphore with a six-membered ring bridging the C11=C12-C13 positions (BR6.11) are measured by picosecond transient absorption and picosecond time-resolved fluorescence spectroscopy. Time-dependent intensity and spectral changes in absorption in the 570-650-nm region are monitored for delays as long as 5 ns after the 7-ps, 573-nm excitation of BR6.11. Two intermediates, J6.11 and K6.11/1, both with enhanced absorption to the red (> 600 nm) of the BR6.11 spectrum are observed within approximately 50 ps. The J6.11 intermediate decays with a time constant of 12 +/- 3 ps to form K6.11/1. The K6.11/1 intermediate decays with an approximately 100-ps time constant to form a third intermediate, K6.11/2, which is observed through diminished 650-nm absorption (relative to that of K6.11/1). No other transient absorption changes are found during the remainder of the initial 5-ns period of the BR6.11 photoreaction. Fluorescence in the 650-900-nm region is observed from BR6.11, K6.11/1, and K6.11/2, but no emission assignable to J6.11 is found. The BR6.11 fluroescence spectrum has a approximately 725-nm maximum which is blue-shifted by approximately 15 nm relative to that of native BR-570 and is 4.2 +/- 1.5 times larger in intensity (same sample optical density). No differences in the profile of the fluorescence spectra of BR6.11 and the intermediates K6.11/1 and K6.11/2 are observed. Following ground-state depletion of the BR6.11 population, the time-resolved fluroescence intensity monitored at 725 nm increases with two time constants, 12 +/- 3 and approximately 100 ps, both of which correlate well with changes in the picosecond transient absorption data. The resonance Raman spectrum of ground-state BR6.11, measured with low-energy, 560-nm excitation, is significantly different from the spectrum of native BR-570, thus confirming that the picosecond transient absorption and picosecond time resolved fluorescence data are assignable to BR6.11 and its photoreaction alone and not to BR-570 reformed during there constitution process (<5% of the BR6.11 sample could be attributed to native BR-570).The J6.11 and K6.11 absorption and fluorescence data presented here are generally analogous to those measured for native J-625 and K-590, respectively, and therefore, the primary events in the BR6.11 photoreaction can be correlated with those in the native BR photocycle. The BR6.11 photoreaction, however, exhibits important differences including slower formation rates for J and K intermediates as well as the presence of a second K intermediate. These results demonstrate that the restricted motion in the C11=C12-C13 region of retinal found in BR6.11 does not greatly change the overall photoreaction mechanism,but does alter the rates at which processes occur.

Bacteriorhodopsins↗
PubMed1999

Absorption of L-DOPA from the proximal small intestine studied in the rhesus monkey by positron emission tomography.

Positron emission tomography (PET) seems to be a valuable method for the understanding of intestinal absorption mechanisms, for simultaneous quantitation of absorption rate and distribution kinetics to the tissues of interest after oral drug delivery. PET was evaluated in three Rhesus monkeys for quantitation of the absorption rate from the gastrointestinal tract and the distribution kinetics into different organs. To obtain optimal standardized conditions for the measurement of absorption the drug was administered via a naso-duodenal catheter directly to the absorption site in the proximal small intestine. l-DOPA was used as study drug given in a suspension together with carbidopa and the radiomarker l-[beta-11C]DOPA. The l-DOPA suspension was given into the duodenum without and after administration of a suspension of six l-amino acids (120 mM) in order to investigate any interaction on the intestinal absorption and distribution of l-DOPA into the liver and brain tissue. Intestinal absorption was in general minor during the first study period and higher together with administered l-amino acids. The somewhat contradictory result with increased absorption when amino acids were present in the intestinal lumen, may be a consequence of increased intestinal motility initiated by the nutrient load.

Animals↗