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PubMed1997

Pre- and postprandial total serum bile acid concentration following acute liver damage in dogs.

The importance of preprandial and postprandial total bile acids were investigated in dogs with liver damage induced by carbon tetrachloride (CCl4) administration. Six healthy and mature dogs were used. After base-line clinical and biochemical examinations, hepatocellular damage was induced by oral CCl4 administration. Determinations of plasma total protein (TP), albumin (Alb), total and direct bilirubin (TBil, DBil), alanine aminotransferase (ALT) and alkaline phosphate (ALP) along with histologic examination of the livers 10 days following CCl4 administration were conducted to ensure that hepatic damage was in fact induced by the CCl4 administration. Twelve h fasting preprandial and 2 h postprandial serum total bile acids (PRSBA, POSBA) concentrations were also measured. The median plasma TP, Alb, TBil and DBil concentrations did not show any difference (P > 0.05) during the study. Plasma ALT activities increased significantly (P < 0.05, P < 0.01) between on the 3rd and 10th days of the experiment. The median serum values of PRSBA and POSBA were significantly different (P < 0.01) on the first day and continued to be different during the experiment. In conclusion, POSBA seemed to be more reliable than PRSBA in the diagnosis of hepatic necrosis.

Acute Disease↗
PubMed1993

The evaluation of the isolated perfused liver as a model for the assessment of liver preservation.

An ex vivo isolated perfused porcine liver model was tested to assess its suitability for rapid, reliable and relatively cheap testing of organ preservation solutions for liver transplantation. The model consists of a machine driven recirculating system incorporating an organ chamber, blood pump and membrane oxygenator. Autologous blood was used for perfusion for a period of 2 h at a temperature of 37 degrees C. The model was tested with five groups of livers which had sustained varying degrees of injury ranging from minimally damaged to those known to be incapable of sustaining life when used for liver transplantation. The groups of livers were: (i) controls; (ii) preserved in University of Wisconsin solution (UW) for 6 h; (iii) preserved in an albumin-based extracellular fluid (ALB) for 6 h; (iv) preserved in UW for 18 h; and (v) preserved in ALB for 18 h. Bile production was found to be a reliable parameter of preservation damage. Changes in perfusate levels of aspartate aminotransferase, potassium, glucose and calcium also occurred in relationship to preservation damage. In contrast, weight gain of the liver, sequestration of the white cells and platelets in the liver, urea production and oxygen consumption were unreliable predictors of liver damage. Histology of biopsy specimens revealed apparently well preserved livers in all cases after preservation but before perfusion, but serious abnormalities after perfusion in long preserved livers, with features in these suggestive of damage to the sinusoidal endothelium. We believe that the model is a worthwhile adjunct to research into liver preservation.

Adenosine↗
PubMed1992

Lipoprotein(a) concentration in diabetes: relationship to proteinuria and diabetes control.

Diabetic patients are at increased risk of cardiovascular disease, particularly when proteinuria is present. Lipoprotein(a)[Lp(a)] levels were assessed in 37 patients with insulin dependent (IDDM) and in 75 patients with non-insulin dependent (NIDDM) diabetes who showed varying degrees of proteinuria and glycaemic control. Median Lp(a) in 112 diabetic patients was significantly greater than in 116 healthy controls (113 vs 48 mg/L; p less than 0.01). 86 of the patients had first morning urine albumin concentration less than 30 mg/L (normoalbuminuria = NA), 16 patients 30-200 mg/L (microalbuminuria = MA) and ten patients greater than 200 mg/L (albuminuria = ALB). There was no significant difference in median Lp(a) concentration between the three groups (NA = 108, MA = 163, ALB = 98 mg/L; p greater than 0.5). No significant difference in median Lp(a) or NIDDM treated with oral agents and/or diet (120, 98, 115 mg/L respectively; p greater than 0.7). When the 86 NA patients were divided on the basis of median fructosamine concentration (357 mumol/L), no significant difference was found in median Lp(a) levels between those grouped below or above this median (98 mg/L vs 118 mg/L; p greater than 0.5). Across all diabetics studied there was no significant correlation present between Lp(a) and urinary protein or glycaemic control. These cross-sectional results suggest that median Lp(a) concentration is increased in both IDDM and NIDDM patients, but this increase is not related to the degree of proteinuria or short-term glycaemic control.

Adolescent↗
PubMed1988

Acute and long-term renal effects of angiotensin converting enzyme inhibition in normotensive, normoalbuminuric insulin-dependent diabetic patients.

Glomerular filtration rate (GFR) (thalamate clearance), renal plasma flow (RPF) (hippuran clearance), and urinary albumin excretion rate (AER) were measured in 10 normoalbuminuric, normotensive insulin-dependent diabetic patients and 8 normal subjects before and during acute angiotensin converting enzyme (ACE) inhibition by means of enalapril (10 mg IV). The effect of placebo versus enalapril (30 mg day-1) was also studied for 3-month treatment periods in the insulin-dependent diabetic patients. Acute ACE-inhibition caused a decline in filtration fraction (FF) from 0.259 +/- 0.011 (+/- SE) to 0.237 +/- 0.013 (2p less than 0.01) in the diabetic patients, and from 0.210 +/- 0.010 to 0.188 +/- 0.006 (2p less than 0.02) in the normal subjects. Mean arterial blood pressure was lowered from 90 +/- 1 to 84 +/- 2 mmHg (2p less than 0.01) and from 91 +/- 1 to 86 +/- 2 mmHg (2p less than 0.05). No significant change in blood glucose, AER or fractional albumin excretion (theta Alb) was seen in either group. After 3 months of enalapril treatment FF was decreased from 0.253 +/- 0.011 to 0.235 +/- 0.011 (2p less than 0.05), AER from 5.6 x/ divided by 1.7 to 4.3 x/divided by 1.6 micrograms min-1 (2p less than 0.01) and theta Alb from 1.22 +/- 0.22 x 10(-6) to 0.92 +/- 0.12 x 10(-6) (2p less than 0.02). The decline in total renal resistance was not significant (0.175 +/- 0.013 to 0.165 +/- 0.012 mmHg ml-1 min-1) and significant changes in GFR, RPF, mean arterial pressure or HbA1c were not observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed1995

Evidence for a functional alpha 1A- (alpha 1C-) adrenoceptor mediating contraction of the rat epididymal vas deferens and an alpha 1B-adrenoceptor mediating contraction of the rat spleen.

1. The alpha 1-adrenoceptor subtype mediating contraction of the rat epididymal vas deferens and rat spleen has been investigated by use of alpha 1-adrenoceptor antagonists that have shown selectivity between the different cloned receptor subtypes. 2. In the rat epididymal vas deferens the potency of noradrenaline and phenylephrine was increased in the presence of neuronal and extra-neuronal uptake blockers, cocaine and beta-oestradiol, but these did not alter that of methoxamine. The order of potency of the agonists in the presence or absence of uptake blockade was noradrenaline > phenylephrine > methoxamine. In the rat spleen the potency of these agonists was not altered in the presence of cocaine and beta-oestradiol, and their order of potency was the same as in the vas deferens. 3. The non subtype selective alpha 1-adrenoceptor antagonist prazosin (up to 1 x 10(-7) M) was found to antagonize contractions to noradrenaline in the vas deferens competitively (pA2 9.2), but only in a non competitive manner in the spleen. Contractions to phenylephrine in the spleen however were competitively antagonized by prazosin (up to 1 x 10(-7) M) with a pA2 of 9.2. This suggests that there is an alpha 1- and a non alpha 1-adrenoceptor response to noradrenaline in the rat spleen. 4. Pretreatment with chlorethylclonidine (10(-4) M for 30 min) did not alter the noradrenaline contractions in the vas deferens, but contractions to noradrenaline and phenylephrine in the spleen were shifted 30 and 300 fold to the right of the control curve, respectively. This suggests that only the contractions in the spleen were mediated by alpha 1B-adrenoceptors. 5. The noradrenaline contractions in the vas deferens were competitively antagonized by WB 4101 (pA29.6), 5-methyl-urapidil (pA2 8.7), phentolamine (pA2 8.3), benoxathian (pA2 9.4), spiperone (pA2 7.5),indoramin (pA2 8.4) and BMY 7378 (pA2 6.7), consistent with the affinities of these antagonists in binding studies on tissue alpha 1A-adrenoceptors. These values correlated best with their published affinities on the expressed alpha 1c-adrenoceptor clone and poorly with those at either the expressed alpha lb- or alpha 1d adrenoceptor clones. Therefore the classical alpha 1A-adrenoceptor appears to be the same as the expressed alpha lc-adrenoceptor clone.6. The phenylephrine contractions in the spleen were competitively antagonized by WB 4101 (pA2 8.1),5-methyl-urapidil (pA2 7.1), phentolamine (pA2 7.3), benoxathian (pA2 7.4), spiperone (pA2 7.9),indoramin (pA2 7.5) and BMY 7378 (pA2 7.4), consistent with the affinities of these antagonists in binding studies on tissue alB-adrenoceptors. The pA2 values correlated best with the published affinities of these compounds on the expressed alb-adrenoceptor clone and poorly with those at either the expressed alpha ld- or alpha lc-adrenoceptor clones. Therefore the alpha lB-adrenoceptor appears to be the same as the expressed alpha lb-adrenoceptor clone.7. The results provide pharmacological evidence that the alpha1-adrenoceptor mediating noradrenaline contractions in the epididymal portion of the rat vas deferens is the alpha 1A-(alpha lC) subtype and that contractions to phenylephrine in the rat spleen are mediated by the alpha 1B-subtype.

Adrenergic alpha-Agonists↗
PubMed1997

Lower serum high-density lipoprotein cholesterol (HDL-C) in major depression and in depressed men with serious suicidal attempts: relationship with immune-inflammatory markers.

Recently, there have been some reports that changes in serum lipid composition may be related to suicide, major depression and immune-inflammatory responses. Findings from our laboratory suggest that major depression is accompanied by reduced formation of cholesteryl esters and perhaps by impairment of reverse cholesterol transport. The latter is reportedly accompanied by lower serum high-density lipoprotein cholesterol (HDL-C). The aim of this study was to examine whether (i) major depression is accompanied by lower serum HDL-C or by abnormal levels of serum total cholesterol, triglycerides, low-density lipoprotein-C (LDL-C) or vitamin E, (ii) suicidal attempts are related to lower serum HDL-C and (iii) there are significant associations between serum HDL-C and immune/inflammatory markers. A total of 36 subjects with major depression, of whom 28 patients showed treatment resistance, as well as 28 normal control subjects, had blood sampled for the assay of the above lipids, serum zinc (Zn), albumin (Alb) and flow cytometric determination of the T-helper/T-suppressor (CD4+/CD8+) T-cell ratio. In total, 28 depressed subjects had repeated measures of these variables both before and after treatment with antidepressants. Serum HDL-C and total cholesterol, as well as the HDL-C/cholesterol ratio, were significantly lower in subjects with major depression than in normal controls. Serum HDL-C levels were significantly lower in depressed men who had at some time made serious suicidal attempts than in those without such suicidal behaviour. Treatment with antidepressants for 5 weeks did not significantly alter either serum HDL-C or other lipid variables. Serum HDL-C levels were significantly and negatively correlated with the (CD4+/CD8+) T-cell ratio, and positively correlated with serum Alb and Zn. These results suggest that (i) lower serum HDL-C levels are a marker for major depression and suicidal behaviour in depressed men, (ii) lower serum HDL-C levels are probably induced by the immune/inflammatory response in depression and (iii) there is impairment of reverse cholesterol transport from the body tissues to the liver.

Adult↗
PubMed1996

Detection of stable and active periodontitis sites by clinical assessment and gingival crevicular acute-phase protein levels.

The aim of the present study was to investigate whether incipient periodontal disease breakdown could be associated with changes in gingival crevicular fluid (GCF) acute-phase protein levels. In addition, the potential of clinical indices to act as predictors of significant attachment level (AL) change was investigated. AL measurements were taken at baseline and 3 months using the Florida Probe stent handpiece from a total of 384 sites in 38 patients. The average standard deviation of duplicate AL measurements was 0.423. When the tolerance method was used to detect significant AL change, 3.9% of the sites lost attachment. When a less stringent criterion of AL change of > or = 1 mm was used 9.9% of the sites lost attachment during the 3-month period. With the exception of probing depth, baseline clinical parameters failed to predict AL change. Fourteen active periodontitis sites that demonstrated significant attachment loss were paired to stable periodontitis sites within the same patient. The levels of four acute-phase proteins, namely alpha 2-macroglobulin (alpha 2-M), alpha 1-antitrypsin (alpha 1-AT), transferrin (TF) and lactoferrin (LF), and also albumin (Alb) were assessed in the same gingival crevicular fluid sample using sandwich ELISAs. Results were expressed either as ng/30 s and ng/microgram Alb. Acute-phase protein levels in GCF failed to differentiate between active and stable periodontitis sites at baseline. In conclusion, the degree of gingival inflammation of the tissues adjacent to the crevice/pocket seems to influence the levels of protease inhibitors and iron-binding proteins in GCF to a greater extent than probing attachment loss.

Acute-Phase Proteins↗
PubMed1979

Comparisons between serum concentrations of thyroxine and thyroxine-binding proteins in samples simultaneously obtained from capillary, peripheral vein, central vein and aorta in newborn infants.

A total number of 40 newborn infants with various maturity were studied: 13 babies without perinatal events, 19 infants recovered from transient diseases, 6 infants with idiopathic respiratory distress syndrome and 2 infants with asphyxia indicating artificial ventilation. Comparisons were performed between serum concentrations of thyroxine (T4), thyroxine-binding globulin (TBG), prealbumin (TBPA) and albumin (Alb) in capillary versus peripheral vein, aorta versus central vein and, finally, in peripheral versus central veins. In healthy infants serum T4 concentrations in capillary blood and peripheral vein did not differ significantly. Although serum concentrations of thyroid hormone-binding proteins tended to be increased in aortic compared to central venous specimens no statistically significant differences appeared. In infants in good clinical conditions serum T4, TBG, TBPA, and Alb levels were 6--8% higher in peripheral than in central veins, possibly primarily due to a hemo-concentrating effect of venous stasis. Therefore, in evaluation of the thyroid variables in newborn infants the technique of blood sampling must be considered. In most infants with idiopathic respiratory distress syndrome and in one asphyxiated baby a remarkable tendency to a low serum TBG and T4 concentration in peripheral compared to central vein samples were observed.

Aorta↗
PubMed2005

Hepatocyte-like cells from directed differentiation of mouse bone marrow cells in vitro.

AIM: To design the effective directed differentiation medium to differentiate bone marrow cells into hepatocyte-like cells. METHODS: Bone marrow cells were cultured in the directed differentiation media including fibroblast growth factor-4 (FGF-4) and oncostatin M (OSM). Hepatocyte-like cells from directed differentiation of bone marrow cells were identified through cell morphology, RNA expressions by reverse transcriptase-polymerase chain reaction (RT-PCR), protein expressions by Western blot, and hepatocellular synthesis and metabolism functions by albumin ELISA, Periodic acid-Shiff staining and urea assay. RESULTS: Some epithelial-like cells or polygonal cells appeared and increased in the course of the cell directed differentiation. Hepatocyte nucleur factor-3beta (HNF-3beta, albumin (ALB), cytokeratin 18 (CK18), transthyretin (TTR), glucose-6-phosphate (G-6-Pase), and tyrosine aminotransferase (TAT) mRNA were expressed in the course of the directed differentiation. The directed differentiated cells on d 21 expressed HNF-3? ALB, and CK18 proteins. The directed differentiated cells produced albumin and synthesized urea in a time-dependent manner. They could also synthesize glycogen. CONCLUSION: Our differentiation media, including FGF-4 and OSM, are effective to differentiate bone marrow cells into hepatocyte-like cells, which could be used for hepatocyte resources for bioartificial liver or hepatocyte transplantation.

Albumins↗
PubMed1995

Haematological and biochemical changes in horses competing in a 3 Star horse trial and 3-day-event.

Haematological and biochemical changes in horses competing in the Endurance Test (Phase T and D) of an advanced Horse Trial (HT, n = 22) and the Endurance Test (Phases A-D) of an advanced (CCI) 3-day-event (TD, n = 11) over a similar course on the same day were studied. Environmental conditions during the event were cool (5.5-11.1 degrees C). Blood samples were collected from the horses in each group the evening prior to the Endurance Test, within 60 s after, and 10 min after, completion of Phase D (cross-country jumping). The following were determined in the blood samples and compared between the 2 groups of horses: packed cell volume (PCV), serum total protein [TP], serum albumin [ALB], plasma lactate [lactate], serum total calcium [TCa], plasma ionised calcium [Ca+2], serum inorganic phosphate [PO4], plasma pH, plasma sodium [Na], plasma potassium [K], serum chloride [Cl], serum urea nitrogen [SUN], serum creatinine [Cr] and serum glucose concentrations and aspartate aminotransferase (AST) and creatine kinase (CK) activities. The PCV and [Cr] were higher in the TD group and approached significance (P = 0.063 and P = 0.057, respectively). The [TP], [ALB], [Na], glucose concentration and CK, and AST were significantly higher and [Cl] and [PO4] were significantly lower in the TD group after exercise when compared to the HT group. It was deduced from these data that the horses competing in the 3-day-event experienced greater fluid and electrolyte losses, reduced glomerular filtration, higher glycogenolysis and had greater leakage of enzymes from working muscles during competition than horses competing in the horse trial.

Animals↗
PubMed2005

The absence of p53 promotes metastasis in a novel somatic mouse model for hepatocellular carcinoma.

We have generated a mouse model for hepatocellular carcinoma using somatic delivery of oncogene-bearing avian retroviral vectors to the liver cells of mice expressing the viral receptor TVA under the control of the albumin gene promoter (Alb-TVA mice). Viruses encoding mouse polyoma virus middle T antigen (PyMT) induced tumors, which can be visualized with magnetic resonance imaging, in 65% of TVA-positive animals. While these tumors can exceed 10 mm in diameter, they do not invade locally or metastasize to the lungs. Delivery of PyMT-expressing viruses to Alb-TVA mice lacking an intact p53 gene does not increase tumor incidence. However, the resulting tumors are poorly differentiated, invasive, and metastatic to the lungs. Gene expression microarrays identified over 100 genes that are differentially expressed between tumors found in p53 wild-type and p53 null mice. Some of these genes, such as cathepsin E and Igf2, have been previously implicated in tumor cell migration and invasion. Tumors induced in p53 null, TVA transgenic mice by PyMT mutants with changes in specific tyrosine residues fail to form metastases, indicating that metastasis is dependent on both the oncogene and the absence of p53.

Animals↗
PubMed2004

Postexercise protein metabolism in older and younger men following moderate-intensity aerobic exercise.

Regular aerobic exercise strongly influences muscle metabolism in elderly and young; however, the acute effects of aerobic exercise on protein metabolism are not fully understood. We investigated the effect of a single bout of moderate walking (45 min at approximately 40% of peak O2 consumption) on postexercise (POST-EX) muscle metabolism and synthesis of plasma proteins [albumin (ALB) and fibrinogen (FIB)] in untrained older (n = 6) and younger (n = 6) men. We measured muscle phenylalanine (Phe) kinetics before (REST) and POST-EX (10, 60, and 180 min) using l-[ring-2H5]phenylalanine infusion, femoral arteriovenous blood samples, and muscle biopsies. All data are presented as the difference from REST (at 10, 60, and 180 min POST-EX). Mixed muscle fractional synthesis rate (FSR) increased significantly at 10 min POST-EX in both the younger (0.0363%/h) and older men (0.0830%/h), with the younger men staying elevated through 60 min POST-EX (0.0253%/h). ALB FSR increased at 10 min POST-EX in the younger men only (2.30%/day), whereas FIB FSR was elevated in both groups through 180 min POST-EX (younger men = 4.149, older men = 4.107%/day). Muscle protein turnover was also increased, with increases in synthesis and breakdown in younger and older men. Phe rate of disappearance (synthesis) was increased in both groups at 10 min POST-EX and remained elevated through 60 min POST-EX in the older men. A bout of moderate-intensity aerobic exercise induces short-term increases in muscle and plasma protein synthesis in both younger and older men. Aging per se does not diminish the protein metabolic capacity of the elderly to respond to acute aerobic exercise.

Adult↗
PubMed2003

Effect of bronchial artery blood flow on cardiopulmonary bypass-induced lung injury.

Cardiovascular surgery requiring cardiopulmonary bypass (CPB) is frequently complicated by postoperative lung injury. Bronchial artery (BA) blood flow has been hypothesized to attenuate this injury. The purpose of the present study was to determine the effect of BA blood flow on CPB-induced lung injury in anesthetized pigs. In eight pigs (BA ligated) the BA was ligated, whereas in six pigs (BA patent) the BA was identified but left intact. Warm (37 degrees C) CPB was then performed in all pigs with complete occlusion of the pulmonary artery and deflated lungs to maximize lung injury. BA ligation significantly exacerbated nearly all aspects of pulmonary function beginning at 5 min post-CPB. At 25 min, BA-ligated pigs had a lower arterial Po(2) at a fraction of inspired oxygen of 1.0 (52 +/- 5 vs. 312 +/- 58 mmHg) and greater peak tracheal pressure (39 +/- 6 vs. 15 +/- 4 mmHg), pulmonary vascular resistance (11 +/- 1 vs. 6 +/- 1 mmHg x l(-1) x min), plasma TNF-alpha (1.2 +/- 0.60 vs. 0.59 +/- 0.092 ng/ml), extravascular lung water (11.7 +/- 1.2 vs. 7.7 +/- 0.5 ml/g blood-free dry weight), and pulmonary vascular protein permeability, as assessed by a decreased reflection coefficient for albumin (sigma(alb); 0.53 +/- 0.1 vs. 0.82 +/- 0.05). There was a negative correlation (R = 0.95, P < 0.001) between sigma(alb) and the 25-min plasma TNF-alpha concentration. These results suggest that a severe decrease in BA blood flow during and after warm CPB causes increased pulmonary vascular permeability, edema formation, cytokine production, and severe arterial hypoxemia secondary to intrapulmonary shunt.

Analysis of Variance↗
PubMed2004

Effects of the taxanes paclitaxel and docetaxel on edema formation and interstitial fluid pressure.

Interstitial fluid pressure (P(if)) is important for maintaining constant interstitial fluid volume. In several acute inflammatory reactions, a dramatic lowering of P(if) has been observed, increasing transcapillary filtration pressure and favoring initial and rapid edema formation. This lowering of P(if) seems to involve dynamic beta(1)-integrin-mediated interactions between connective tissue cells and extracellular matrix (ECM) fibers. beta(1)-Integrins are adhesion receptors responsible for the attachment of connective tissue cells to the ECM providing a force-transmitting physical link between the ECM and cytoskeleton. Disruption of actin filaments leads to lowering of P(if) and edema formation, suggesting a role for actin filaments. The aim of this study was to further investigate the role of the cytoskeleton in the control of P(if) by studying the effect of microtubuli fixation using paclitaxel and docetaxel. P(if) was measured with the micropuncture technique. Albumin extravasation (E(alb)) was measured using (125)I-labeled albumin. Paclitaxel and docetaxel were tested locally on foot skin in female Wistar rats. Paclitaxel (6 mg/ml) reduced P(if) from -1.5 +/- 1.0 mmHg in controls to -4.9 +/- 2.6 mmHg after 30 min (P < 0.05) in a dose-dependent manner (P < 0.05). Docetaxel caused a similar lowering of P(if). Both paclitaxel and docetaxel increased E(alb) compared with Cremophor EL and saline control (P < 0.05). Pretreatment with phalloidin before paclitaxel, causing fixation of actin filaments, abolished the lowering of P(if) caused by paclitaxel. This study confirms several previous studies demonstrating that connective tissue cells influence P(if) and edema formation.

Animals↗
PubMed2000

Effect of time and vascular pressure on permeability and cyclic nucleotides in ischemic lungs.

We previously found that increased intravascular pressure decreased ischemic lung injury by a nitric oxide (NO)-dependent mechanism (Becker PM, Buchanan W, and Sylvester JT. J Appl Physiol 84: 803-808, 1998). To determine the role of cyclic nucleotides in this response, we measured the reflection coefficient for albumin (sigma(alb)), fluid flux (), cGMP, and cAMP in ferret lungs subjected to either 45 min ("short"; n = 7) or 180 min ("long") of ventilated ischemia. Long ischemic lungs had "low" (1-2 mmHg, n = 8) or "high" (7-8 mmHg, n = 6) vascular pressure. Other long low lungs were treated with the NO donor (Z)-1-[N-(3-ammoniopropyl)-N-(n-propyl)amino]diazen-1-ium -1, 2-diolate (PAPA-NONOate; 5 x 10(-4) M, n = 6) or 8-bromo-cGMP (5 x 10(-4) M, n = 6). Compared with short ischemia, long low ischemia decreased sigma(alb) (0.23 +/- 0.04 vs. 0.73 +/- 0.08; P < 0.05) and increased (1.93 +/- 0.26 vs. 0.58 +/- 0.22 ml. min(-1). 100 g(-1); P < 0.05). High pressure prevented these changes. Lung cGMP decreased by 66% in long compared with short ischemia. Lung cAMP did not change. PAPA-NONOate and 8-bromo-cGMP increased lung cGMP, but only 8-bromo-cGMP decreased permeability. These results suggest that ischemic vascular injury was, in part, mediated by a decrease in cGMP. Increased vascular pressure prevented injury by a cGMP-independent mechanism that could not be mimicked by administration of exogenous NO.

Animals↗
PubMed2001

NEM and filipin increase albumin transport in lung microvessels.

This study was undertaken to evaluate the role of transcytosis as a bulk transfer mechanism for the passage of albumin from blood to tissue. Isolated rat lungs were continuously weighed and perfused with an albumin-serum buffer solution under strictly controlled hemodynamic conditions, which allowed measurements of microvascular pressure and of the capillary filtration coefficient (L(p)S). With the use of a tissue uptake technique, it was possible to determine lung albumin clearance under isogravimetric conditions (Cl(iso)), or at elevated filtration rates, to obtain an "apparent albumin reflection coefficient" (sigma(alb)). Experiments were performed during control and after reducing lung temperature from 35 degrees to 22 degrees C and after infusions of the transcytosis inhibitors N-ethylmaleimide (NEM) or filipin. Cooling moderately increased vascular resistance and reduced L(p)S and Cl(iso) largely in proportion to the induced increases in viscosity. At 35 degrees C, NEM (0.13 mM) caused a marked increase in L(p)5 and in Cl(150) and also caused a reduction in sigma(alb.) Furthermore, Cl(iso) increased for the highest dose of filipin tested (1.8 microg/ml). The demonstrated relative cooling insensitivity of the transfer of albumin across the endothelium in rat lungs does not support the contention of transcytosis of proteins across the endothelium. Furthermore, neither NEM nor filipin inhibited lung microvascular albumin transport, but actually increased lung endothelial permeability.

Algorithms↗
PubMed2001

Cytochalasin D induces edema formation and lowering of interstitial fluid pressure in rat dermis.

The increased capillary fluid filtration required to create a rapid edema formation in acute inflammation can be generated by lowering the interstitial fluid pressure (P(IF)). The lowering of P(IF) appears to involve dynamic beta(1)-integrin-mediated interactions between dermal cells and extracellular matrix fibers. The present study specifically investigates the role of the cell cytoskeleton, i.e., the contractile apparatus of cells, in controlling P(IF) in rat skin as the integrins are linked to both the cytoskeleton and the extracellular matrix. P(IF) was measured using a micropuncture technique in the dorsal skin of the hind paw at a depth of 0.2--0.5 mm and following the induction of circulatory arrest with the intravenous injection of KCl in pentobarbital anesthesia. This procedure prevented the transcapillary flux of fluid and protein leading to edema formation in acute inflammation, which in turn can increase the P(IF) and therefore potentially mask a decrease of P(IF). Control P(IF) (n = 42) averaged -0.8 +/- 0.5 (means +/- SD) mmHg. In the first group of experiments, subdermal injection of 2 microl cytochalasin D, a microfilament-disrupting drug, lowered P(IF) to an average of -2.8 +/- 0.7 mmHg within 40 min postinjection (P < 0.05 compared with control). Subdermal injection of vehicle (10% DMSO in PBS or PBS alone) did not change the P(IF) (P > 0.05). Lowering of the P(IF) was not observed after the injection of colchicine or nocodazole, which specifically disrupts microtubuli in cultured cells. In the second group of experiments, 2 microl of cytochalasin D injected subdermally into rats with intact circulation increased the total tissue water (TTW) and albumin extravasation rate (E(ALB)) by 0.7 +/- 0.2 and 0.4 +/- 0.3 ml/g dry wt, respectively (P < 0.05 compared with vehicle). Nocodazole and colchicine did not significantly alter the TTW or E(ALB) compared with the vehicle (P > 0.05). Taken together, these findings strongly suggest that the connective tissue cells can participate in control of P(IF) via the actin filament system. In addition, the observation that subdermal injection of cytochalasin D lowered P(IF) indicates that a dynamic assembly and disassembly of actin filaments also occurs in the cells of dermal tissues in vivo.

Animals↗
PubMed2001

A quantitative analysis of the glomerular charge barrier in the rat.

Modifying the ionic strength (I) is a gentle way to alter charge interactions, but it cannot be done for studies of the glomerular sieving of proteins in vivo. We therefore perfused 18 isolated rat kidneys with albumin solutions of different ionic strengths at a low temperature (cIPK) to inhibit tubular uptake and protease activity. Four anionic proteins were studied, namely albumin (Alb), orosomucoid (Oro), ovalbumin (Ova), and anionic horseradish peroxidase (aHRP), together with the neutral polymer Ficoll. With normal ionic strength of the perfusate (152 mM), the fractional clearance (theta) was 0.0018 +/- 0.0003 for Alb, 0.0033 +/- 0.0003 for Oro, 0.090 +/- 0.008 for Ova, and 0.062 +/- 0.002 for aHRP. These theta values were all lower than for Ficoll of similar hydrodynamic size; e.g., theta(Ficoll 36 A) was >20 times higher than theta for albumin. Low ionic strength (34 mM) increased size selectivity as theta for anionic proteins and Ficoll fell, suggesting a reduction in small-pore radius from 44 +/- 0.4 to 41 +/- 0.5 A, P < 0.01. In contrast, low I reduced the charge density of the membrane, omega, to one-quarter of the 20--50 meq/l estimated at normal I. These dynamic changes in omega seem to be due to volume alterations of the charged gel, fluid shifts that easily are accounted for by the changes in electroosmotic pressures. The finding that low ionic strength induces inverse effects on size selectivity and charge density strongly suggests that separate structures of the glomerular wall are responsible for the two properties.

Albumins↗