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PubMed1996

Transvascular albumin transport and protein replenishment after haemorrhage in the chronically catheterized pregnant rabbit.

Pregnancy is characterized by increases in both blood and interstitial volumes, but the mechanisms are unknown. To test the hypotheses that blood volume (BV) recovery after haemorrhage in pregnant (P) is faster than in nonpregnant (NP) rabbits, and that this can be explained by a higher capillary filtration, a 20% BV haemorrhage was produced in a group of 7 P and 7 NP rabbits. We determined the BV recovery (measured by 99Tc), the total plasma protein mass and the haematocrit at 10, 20, 30, 60 and 1440 min after haemorrhage. Arterial and venous pressures and heart rate were measured during a 30-min control period, during the 10 min of haemorrhage, and for the following 70 min. In a separate group of P and NP rabbits, 125I-labelled albumin was infused and blood samples were obtained at 10, 20, and 30 min. Capillary filtration was expressed as the percentage of radioactive albumin that left the intravascular space after 30 min. No differences were found in the rate of BV recovery, arterial and venous pressures, or heart rate response between P and NP animals (P > 0.1). By 24 h total plasma protein mass (TPPM) was significantly increased above baseline in the P rabbits by an average+SEM of 13 + 3.7%, but not in NP rabbits (5 + 4.5%). At 30 min, the amount of labelled albumin in the intravascular space decreased by 15.4 + 3.4% for Pv. 8.2 + 1.2% for NP rabbits (P < 0.05). There was a high correlation between TPPM recovery and BV recovery in the P (r = 0.96) and NP rabbits (r = 0.95). In conclusion, we did not find differences in the rate at which the BV recovered during pregnancy, despite the increased capillary permeability. During pregnancy, the combination of the latter with an increase in the TPPM elevation above pre-haemorrhage levels suggests a faster rate of protein mobilization.

Adaptation, Physiological↗
PubMed1993

Blood-tissue transport of exogenous albumin and immunoglobulin G in genetically analbuminemic rats.

Tracer uptake studies were carried out in adult female Nagase (NA) strain analbuminemic rats [derived from Sprague-Dawley (SD) stock] and in adult female SD controls to determine the extent to which capillary permeability to plasma proteins is altered in the absence of endogenous albumin. Accessory measurements (arterial pressure, central venous pressure, plasma and interstitial fluid protein concentrations and oncotic pressures, plasma volume, and interstitial fluid volume) confirm the report of Joles et al. [Am. J. Physiol. 257 (Renal Fluid Electrolyte Physiol. 26): F23-F28, 1989] that shows elevated plasma volumes, normal interstitial fluid volumes, nearly normal plasma oncotic pressures (due to elevated globulin concentrations), and lower interstitial fluid oncotic pressures. In skin, skeletal muscles, and heart muscle, clearances of exogenous heterologous (bovine) albumin were 20-40% higher in NA than in SD controls. In intestine, albumin clearances were 20-30% lower. In NA rats blood-to-tissue clearances of heterologous (bovine) immunoglobulin G in skin and heart were higher and in the intestine they were lower than in SD controls; however, clearances in skeletal muscles were not elevated. The differences between NA and SD are small compared with the large increases in macromolecular permeabilities reported by others for organs and single microvessels perfused with albumin-free fluids.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1978

Pulmonary ultrastructure of the late aspects of human paraquat poisoning.

The pulmonary ultrastructure of the late aspects of a case of human paraquat poisoning is investigated and compared with normal human pulmonary ultrastructure. Alveoli in the paraquat patient are numerically reduced in comparison to the control. They are filled with edematous proteinaceous plasma-like fluid containing erythrocytes, macrophages, leukocytes, fibroblast-like cells, platelets, and fibrin. These alveoli are lined by granular pneumocytes. Interstitial areas in the paraquat patient are greatly expanded and there are no alveolar septums. Interstitial areas contain proteinaceous plasma-like material, collagen, fibrin, platelets, mature fibroblasts, plasma cells, many leukocytes, numerous erythrocytes, and capillaries. Capillary permeability seems to be enhanced in the paraquat patient either by vesicles forming transendothelial channels or pores or by disruption of endothelial cells.

Adolescent↗
PubMed1995

Characterization of mechanisms causing hypoalbuminemia in rats with long-term bile duct ligation.

Albumin kinetics and albumin synthesis were studied in rats with chronic bile duct ligation and compared with pair-fed control rats. The plasma albumin concentration was significantly reduced in bile duct ligated rats as compared to control rats, averaging 35 +/- 1 vs 40 +/- 2 g/l after 2 weeks and 28 +/- 3 vs 38 +/- 5 g/l after 4 weeks of bile duct ligation. Two weeks after bile duct ligation, the transcapillary escape rate of albumin was increased by 60% in bile duct ligated rats, whereas the plasma volume was unchanged. Albumin synthesis expressed as a fraction of total liver protein synthesis, as assessed by the 'flooding' dose method using [3H]phenylalanine, was decreased by 46% in bile duct ligated rats. However, absolute albumin synthesis expressed per 100 g body weight was not different from control rats. Four weeks after bile duct ligation, the transcapillary escape rate of albumin was no longer different, whereas the plasma volume was increased by 38% in bile duct ligated rats. At this time point, albumin synthesis as a fraction of total liver protein synthesis was decreased by 60% in bile duct ligated rats, and absolute albumin synthesis expressed per 100 g body weight averaged 80 +/- 8 vs 53 +/- 12 mg/(day x 100 g) in control and bile duct ligated rats (p < 0.05). The hepatic steady-state levels of albumin mRNA determined by Northern blot analysis were decreased in bile duct ligated rats at both 2 and 4 weeks after surgery. The studies suggest that reduced plasma albumin concentrations in bile duct ligated rats are caused by increased capillary permeability and lack of compensatory increase in albumin synthesis 2 weeks, and by increased plasma volume and decreased albumin synthesis 4 weeks after surgery.

Animals↗
PubMed1980

Postpartum capillary leak syndrome. A case report.

A 29-year old healthy woman suddenly developed hypovolemic shock, anasarca, pleural effusion, and ascites in the postpartum period. Plasma leakage was thought to be caused by generalized increased capillary permeability. She was treated successfully with massive plasma transfusions, administration of norepinephrine, and early institution of respiratory support. The patient has not developed a similar episode during 1 yr of follow-up.

Adult↗
PubMed1979

Blood-brain barrier permeability in senescent rats.

Cerebrovascular permeability to 14C-sucrose was measured in 3-mo-old and 28-mo-old conscious, restrained Fischer 344 male rats. Tracer was injected intravenously in these animals and arterial plasma concentrations were followed for 50 to 240 min, when animals were killed and regional brain radioactivity was measured. Equations derived by a two-compartment diffusion model were fit to concentration data to estimate PA (product of cerebral capillary permeability and surface area) and Ve (cerebral distribution space of 14C-sucrose). PA in 3-mo-old rats averaged 7.53 x 10(-6) sec-1 in 14 cerebral regions, and was not significantly elevated in 28-mo-old rats except possibly at white matter. Ve fell from an average of 0.126 in control rats to 0.070 in 28-mo-old rats. This 45% reduction may reflect a reduced extracellular space in the older animals. The findings do not support the hypothesis that aging of the central nervous system is related to breakdown of the blood-brain barrier.

Aging↗
PubMed1976

Single-passage extraction and permeability estimation of sodium in normal dogs lungs.

Bolus injections of 24NaCl, 131I-albumin, and indocyanine green dye were made into the right atria of anesthetized, ventilated dogs. Blood was sampled from the femoral artery, and from the dilution curves, instantaneous extractions, E2(t), and area averaged extractions, E3(t), were calculated for sodium at various plasma flows (Fp). Flow reduction was produced by transient inferior vena cava obstruction. E2(t) and E3(t) within any dilution curve generally started off with a high value, then decreased with time. The E3 that occurred at the peak of the albumin-dilution curve were about 0.11 for plasma flow of 0.75 liter/min and tended to decrease as flow increased. Parallel study of the sodium extravascular space at equilibrium gave values of 0.3-0.4 g of plasma sodium per g of tissue, suggesting that this volume is not infinitely small. Since the E was low it is unlikely that the high initial E(t) and the decreasing E(t) were due to early back flux. Calculation of capillary permeability surface area product [PS = Fp loge (1 - E)] showed an increasing PS with plasma flows. The injection of 9-mum microspheres at low and high total blood flow gave evidence supporting a decrease of capillary surface area (S) with decreasing total blood flow. Regional pulmonary blood flow also showed marked heterogeneity. Because of the low average extraction of sodium in the lung, insensitivity of the method in normal lungs cannot be excluded.

Animals↗
PubMed1993

Adenosine prevents PMA-induced lung injury via an A2 receptor mechanism.

Previous studies indicate that adenosine attenuates phorbol myristate acetate-(PMA) induced canine lung injury, but the mechanism has not been explained. To evaluate adenosine's protective mechanism, isolated and blood-perfused dog lungs were challenged by PMA (50 micrograms) under control conditions and after both pre- and post-treatment with adenosine and pretreatment with 2-chloro-N6-cyclopentyladenosine (CCPA), 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamido adenosine (CGS 21680C), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; PD-116948), or isoproterenol. Injury was assessed by measurement of the capillary filtration coefficient (Kf,c), and pulmonary vascular resistance was measured. PMA increased the Kf,c (0.170 +/- 0.015 to 1.030 +/- 0.167 ml.min-1.cmH2O-1.100 g lung wet wt-1) and the total pulmonary vascular resistance (18.2 +/- 3.8 to 110.2 +/- 60.8 cmH2O.l-1.min.100 g lung wet wt). Pretreatment with adenosine, A2 agonist, A1 antagonist, and isoproterenol blocked the increase in Kf,c induced by PMA. These agents also slightly attenuated the resistance increase induced by PMA, with the exception of the A1 antagonist, which completely prevented the resistance increase (24.3 +/- 7.8 to 23.4 +/- 8.1 cmH2O.l-1.min.100 g lung wet wt). The A1 agonist also slightly attenuated the increase in Kf,c (0.174 +/- 0.022 to 0.486 +/- 0.128 ml.min-1.cmH2O-1.100 g lung wet wt-1) and did not affect the resistance increase. Posttreatment with adenosine did not significantly affect the changes induced by PMA. These data show that PMA-induced increases in capillary permeability in the isolated blood-perfused dog lung can be blocked by pretreatment with adenosine, which binds the adenosine A2 receptors.

Adenosine↗
PubMed1997

High altitude pulmonary edema.

Altitude, speed and mode of ascent and, above all, individual susceptibility are the most important determinants for the occurrence of high-altitude pulmonary edema (HAPE). This illness usually occurs only 2-5 days after acute exposure to altitudes above 2,500-3,000 m. Chest radiographs and CT scans show a patchy predominantly peripheral distribution of edema. Wedge pressure is normal at rest, and there is an excessive rise in pulmonary artery pressure (Ppa) which precedes edema formation. Bronchoalveolar lavage in patients with advanced HAPE shows evidence of inflammatory response with increased capillary permeability. There are, however, no prospective data indicating whether the inflammatory response is a primary cause of HAPE or a consequence of edema formation. Excessive rise in Ppa appears to be a crucial pathophysiologic factor for HAPE. Recent observations of high Ppa in HAPE-susceptible subjects who did not develop pulmonary edema after rapid ascent to high altitude suggest either that Ppa does not necessarily reflect capillary pressure in these individuals or else that additional factors, such as an inflammatory response and/or a decreased fluid clearance from the lung, are necessary for the development of pulmonary edema. The treatment of choice is immediate descent. When this is impossible and supplemental oxygen is not available, treatment with nifedipine is recommended until descent is possible.

Altitude↗
PubMed1989

Is a decrease in plasma oncotic pressure enough to explain the edema of pregnancy?

The balance of fluid across capillaries is given by the Starling equation. Because the plasma protein concentration (one of its components) is decreased in pregnancy, we decided to explore the question as to whether hypoproteinemia with intact protein mass (produced by blood volume expansion) or hypoproteinemia with decreased total protein mass (produced by removal of circulating proteins) alters the oncotic pressure differences across capillaries. We calculated the oncotic pressure difference obtained in seven nonpregnant ewes during periods of normoproteinemia and hypoproteinemia; the influence of fluid infusion under both conditions was also observed. There was an increase in the oncotic pressure difference across the capillary wall during hypoproteinemia produced by a decrease in the total protein mass (p less than 0.01); however, the response to hypoproteinemia produced by fluid infusion was similar (p greater than 0.1). The venous pressure (used as an index of interstitial fluid pressure changes) did not differ in either hypoproteinemia or fluid infusion. Capillary permeability was decreased during hypoproteinemia, as evidenced by a higher lymph/protein ratio of labeled albumin during the control period (p less than 0.05). In conclusion, during a state of decreased plasma protein concentration similar to that of pregnancy, the difference in the oncotic pressure and hydrostatic pressure forces acting to prevent transfer of fluid to the interstitium is increased. Therefore other factors that influence fluid transfer across the capillaries must be investigated to explain the edema of pregnancy.

Animals↗
PubMed1992

Long-term smoking increases transcapillary escape rate of albumin.

Transcapillary escape rate of albumin was measured in 11 young and 10 healthy, elderly male subjects. Approximately half of the subjects were chronic cigarette smokers. Transcapillary escape rate of albumin expressed as percentage of decrease in specific activity of plasma albumin per hour averaged 12.3% in long-term smokers. This value was significantly elevated and twice as high as values measured in young smokers and in young and elderly non-smokers. It is concluded that capillary permeability to albumin is increased in long-term smokers. Further studies are warranted to examine the pathophysiological mechanism and to what extent this abnormality is reversible.

Adult↗
PubMed1993

[Anti-inflammatory effect of Caragana microphylla Lam].

Caragana microphylla can antagonize the inflammation induced by carrageenin, hot water and croton oil. It can also inhibit the proliferation of granuloma, blood capillary permeability, phagocytic function of mononuclear phagocyte system, and synthesis or release of PGE2 at the inflamed part.

Animals↗
PubMed2004

Herpes simplex virus type 1 and normal protein permeability in the lungs of critically ill patients: a case for low pathogenicity?

INTRODUCTION: The pathogenicity of late respiratory infections with herpes simplex virus type 1 (HSV-1) in the critically ill is unclear. METHODS: In four critically ill patients with persistent pulmonary infiltrates of unknown origin and isolation of HSV-1 from tracheal aspirate or bronchoalveolar lavage fluid, at 7 (1-11) days after start of mechanical ventilatory support, a pulmonary leak index (PLI) for 67Gallium (67Ga)-transferrin (upper limit of normal 14.1 x 10(-3)/min) was measured. RESULTS: The PLI ranged between 7.5 and 14.0 x 10(-3)/min in the study patients. Two patients received a course of acyclovir and all survived. CONCLUSIONS: The normal capillary permeability observed in the lungs argues against pathogenicity of HSV-1 in the critically ill, and favors that isolation of the virus reflects reactivation in the course of serious illness and immunodepresssion, rather than primary or superimposed infection in the lungs.

Adult↗
PubMed2002

Structure and function of endothelial caveolae.

Caveolae are spherical invaginations of the plasma membrane and associated vesicles that are found at high surface densities in most cells, endothelia included. Their structural framework has been shown to consist of oligomerized caveolin molecules interacting with cholesterol and sphingolipids. Caveolae have been involved in many cellular functions such as endocytosis, signal transduction, mechano-transduction, potocytosis, and cholesterol trafficking. Some confusion still persists in the field with respect to the relationship between caveolae and the lipid rafts, which have been involved in many of the above functions. In addition to all these, endothelial caveolae have been involved in capillary permeability by their participation in the process of transcytosis. This short review will focus on their structure and components, methods used to determine these components, and the role of caveolae in the transendothelial exchanges between blood plasma and the interstitial fluid.

Animals↗
PubMed1983

Effect of Escherichia coli endotoxin on dog lung fluid balance.

Endotoxin may cause an increase in pulmonary capillary permeability and thus promote edema formation. We used a gravimetric technique to estimate the pulmonary capillary filtration coefficient (KF) and the maximum capillary pressure at which the lung could maintain a constant weight (Pccritical) in dogs after intravenous administration of Escherichia coli (E. coli) endotoxin. KF should be increased and Pccritical should be decreased by an increase in permeability. Four groups of three to four dogs were given 1, 10, 1,000, or 3,000 micrograms/kg of endotoxin. A fifth group of five dogs, which served as controls, was given no endotoxin. KF was significantly (P less than 0.05) greater than control [0.049 +/- 0.031 (SD) ml . min-1 . mmHg-1] in only the 1-micrograms/kg group (0.100 +/- 0.027), indicating a possible increase in permeability. However, changes in capillary surface area may have affected KF. Pccritical was not significantly different from control (20.7 +/- 2.4 mmHg) in any of the E. coli groups. We conclude from these results that E. coli endotoxin may have caused a slight increase in permeability; however, the lung retained its ability to resist edema formation.

Animals↗
PubMed1989

Effect of acute venous hypertension on erythrocyte, leukocyte, and plasma protein extravasation in the dog hindlimb.

The effect of acute venous hypertension on the extravasation of plasma proteins, erythrocytes, and leukocytes into regional lymph was studied in the dog hindlimb. Although the lymph protein transport sharply rose with hindlimb phlebohypertension, capillary permeability was unchanged with retention in draining lymph of a normal proportion of large to small molecular weight proteins. Leukocyte transport also increased initially but then progressively decreased despite persistent venous hypertension. Lymph transport of erythrocytes was also high during venous hypertension but in contrast to white cells, it remained at that level as long as venous pressure was elevated. These findings suggest that different pathways and mechanisms are involved in the capillary extravasation of plasma proteins and cells capable of intrinsic motility (i.e., leukocytes) and those without independent motion (i.e., erythrocytes).

Animals↗
PubMedDate not supplied

A comparative study on anti-inflammatory activities of the enantiomers, shikonin and alkannin.

A pharmacological comparison between the enantiomers, shikonin (R) and alkannin (S), was made with regard to their inhibitory effects on the increased capillary permeability and thermal edema in rats, using phenylbutazone as a positive control in both models. The results of experiments have shown that there is no significant difference in the anti-inflammatory activity between the two compounds.

Animals↗
PubMedDate not supplied

[Determination and clinical significance of colloid osmotic pressure in pediatric patients].

The clinical significance of colloid osmotic pressure (COP) in transcapillary fluid exchange and water homeostasis in health and disease is described. Under pathophysiological circumstances measurement of COP should be preferred to COP value calculation. After extensive COP experiences in critically ill adults and numerous refinements in COP monitoring technology, COP studies in neonates and paediatric intensive care patients have been published recently. In these patients hypovolaemia and need of volume replacement therapy are often associated with an increase in capillary permeability. Therefore prevention of general and interstitial colloid and fluid overload is a permanent challenge in the care of the young critically ill patient; e.g. in a case report. Consequently regular COP measurements should be considered in paediatric intensive care, especially in case of oncotic volume replacement therapy.

Capillary Permeability↗