The renal effects of a single intravenous dose of two different E. coli lipopolysaccharides (LPS 0111:B4 and LPS 0127:B8), at the same dose of 100 micrograms/kg, were evaluated in euvolemic Munich-Wistar (MW) rats by whole kidney clearance techniques and micropuncture studies. Following LPS infusion, a significant decrease (8%) in mean ...

1. The effects of acute unilateral renal denervation were examined in 17 anaesthetized rats. Renal haemodynamic changes were monitored using standard clearance techniques. Lithium clearance was used to assess fractional proximal sodium and water reabsorption. 2. Denervation resulted in ipsilateral renal vasodilatation with marked natriuresis and diuresis, a small increase ...

To assess the quantitative relation between exposure to airborne cadmium and various markers of renal tubular and glomerular function, 45 male workers employed at a plant that recovers cadmium from industrial waste and 32 male hospital workers of similar age and geographical location were examined. Cumulative external exposure to airborne ...

The glomerular size-selective properties in a patient with "hyponatremic hypertensive syndrome" were investigated before and after administration of the angiotensin-converting enzyme inhibitor enalapril. Hyponatremic hypertensive syndrome is a rare condition of renovascular hypertension characterized by electrolyte abnormalities (hyponatremia, hypokalemia), polyuria, and high renin activity. In this patient a marked increase ...

The tubuloglomerular feedback (TGF) system is less sensitive after extracellular volume expansion (VE). In rats with partial ureteral obstruction, however, we have previously found increased TGF sensitivity during such expansion. Thromboxane A2 (TXA2) has been reported to be increased in the hydronephrotic kidney, and the present study was undertaken to ...

The microvascular mechanisms responsible for oedema formation following the administration of calcium antagonists were studied in 10 healthy volunteers given intravenous felodipine and vehicle in a double-blind crossover trial. Plethysmography and laser Doppler flowmetry were used to measure microvascular parameters. Felodipine increased both skin and forearm blood flow. Due to ...

Systemic hypertension accelerates the progression of glomerular injury. Studies in experimental animals indicate that the beneficial effects of antihypertensive agents may relate to their intrarenal haemodynamic consequences, and specifically to their effects on the arteriolar resistances. Relative afferent arteriolar vasodilation allows transmission of systemic pressure into the glomerular capillary network; ...

Adrenergic activity regulates renal function by several mechanisms. Renal nerves not only exert vasoconstrictor functions but also may influence glomerular hemodynamics by beta-adrenergic activity, especially via the effects on renin angiotensin activity. Little is known of the specific glomerular hemodynamic alterations resulting from beta 1-adrenergic blockade. Current studies examined the ...

Preliminary hemorheologic studies using clinical filtration techniques on blood cell suspensions have suggested that changes in erythrocyte (RBC) deformability occur during left ventricular assist system (LVAS) support. In the biophysics literature, it is generally accepted that the elastic properties of the RBC membrane complex affect the microcirculatory deformability of the ...

Our ability to measure precisely the pressures and flows within the glomerular microcirculation has enabled us to begin to unravel the complex relationship between systemic hypertension and kidney disease. Although a number of factors have been implicated in the development of glomerular sclerosis, one consistent finding has been that glomerular ...

Previous experiments have shown oscillations in proximal tubular pressure in halothane-anesthetized rats. Such oscillations should be due to oscillations in flow rate and should cause periodic oscillations in both distal tubular chloride concentration and distal tubular pressure. The purpose of the study was to test these predictions. In halothane-anesthetized Sprague-Dawley ...

The glomeruli of kidneys subjected to reduced perfusion pressure were examined morphometrically. The left renal artery was narrowed for 30 min in anesthetized dogs with (n = 6) or without (n = 7) converting-enzyme inhibition (captopril). The kidneys were then rapidly fixed by glutaraldehyde perfusion at high flow rate. In ...

The "Gamma Loop" Part I compared a model of rubber tubing to the architecture of the glomerulus with emphasis placed on the observed relationship between the position of the outflow resistance clamp and the perfusion of the loop (1, 2). Part II describes the pressures observed in the different parts ...

The capillary filtration coefficient (CFC) in the human forearm, determined with the 'venous occlusion' method, was found to be about 0.005 ml min-1 100 ml-1 soft tissue mmHg-1 when capillary pressure (Pc) was raised by about 30 mmHg, a finding in accordance with previous literature. With gradually smaller increments of ...

In Munich-Wistar rats, a micropipette was inserted into a first-order branch of the left main renal artery and continuously infused with human/porcine endothelin (0.4 ng/min). Micropuncture measurements revealed substantial differences within the cortical microcirculation of the same left kidney: SNGFR was some 35% lower in glomeruli exposed to endothelin compared ...

To determine whether the accelerated rate of lobe weight gain during severe pulmonary edema is attributed to increased permeability of the microvascular barrier or a loss of tissue forces opposing filtration, the effect of edema on capillary filtration coefficient (Kf,C), interstitial compliance (Ci), and the volume of fluid filtered after ...

The hyperbicarbonatemia of chronic respiratory acidosis is maintained by enhanced bicarbonate reabsorption in the proximal tubule. To investigate the cellular mechanisms involved in this adaptation, cell and luminal pH were measured microfluorometrically using (2",7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein in isolated, microperfused S2 proximal convoluted tubules from control and acidotic rabbits. Chronic respiratory acidosis was ...

We investigated potentiation of atrial peptide (AP)-induced natriuresis by vasopressin in anesthetized rats. Increasing doses of vasopressin potentiated AP-induced natriuresis in a dose-dependent manner, e.g., sodium excretion during AP administration (290 ng/min) was 0.66 +/- 0.16, 2.02 +/- 0.68, 5.21 +/- 1.38 and 7.08 +/- 1.96 mu eq/min during infusion ...

We evaluated the effects of chronic cyclosporine (CsA) administration on the determinants of nephron filtration rate (SNGFR) using micropuncture techniques (mp) in male Munich-Wistar rats. Animals received CsA (30 mg/kg SQ) in olive oil daily for 8 d before mp. Controls (PFC) were pair fed. SNGFR, glomerular capillary hydrostatic pressure ...

1. Twenty-four patients with primary hyperparathyroidism were studied before and 18 restudied 6.5 months (mean) after parathyroidectomy, to investigate the pathogenesis of the hypertension which may accompany this condition. Comparison was made with age-matched patients with essential hypertension and with normotensive control subjects. 2. There was a significant inverse relationship ...

In isolated, dog lung lobes with pulmonary vessels filled with different liquids, we measured the rate of weight gain for 5 or 10 min at constant alveolar and vascular pressures under zone 1 conditions (alveolar pressure greater than vascular pressure). We used six different liquids: syngeneic plasma, whole blood (hematocrit ...

Autoregulation of renal blood flow and filtration rate was studied using micropuncture technique in Munich-Wistar rats with acute water deprivation (AWD) or congestive heart failure (CHF). In the first set of experiments, reduction of renal perfusion pressure to approximately to 70% of its initial value resulted in uncoupling of glomerular ...

1. The distribution of morphological injury was assessed qualitatively and quantitatively in the perfused rat kidney in vitro at controlled rates of oxygen delivery in the presence of low concentrations of erythrocytes. 2. In control kidneys (total oxygen delivery approximately 32 mumol/min per kidney) no injury was seen in the ...

Bicarbonate reabsorption by the immature kidney in response to acute acid-base changes was assessed in 50 anesthetized newborn rabbits before the end of nephrogenesis. The normal newborn rabbit (age 5-12 days) is in a state of hypochloremic metabolic alkalosis (PHCO3-, 31.9 +/- 0.6 mmol/l; PCl-, 83.1 +/- 1.0) and excretes ...

The effect of prior urinary tract obstruction on total CO2 flux in cortical and medullary collecting tubules was examined using an unilateral ureteral obstruction model and isolated tubule in vitro microperfusion. Tubules were obtained from the control and obstructed kidneys after 1, 2, and 4 days of obstruction. Paired comparison ...

Hypertension is a multifactorial disease that is manifested hemodynamically by an increased total peripheral resistance that is more or less uniformly distributed throughout the organ circulations, especially in its target organs, the brain, heart, and kidney. The vasoconstriction involves venules as well as arterioles. The increased afterload that is imposed ...

To elucidate the mechanisms by which indomethacin lowers proteinuria, we studied 20 patients with the nephrotic syndrome. We performed differential macromolecule clearances before and after 3 days of therapy (150 mg/24 h). The fractional clearances of albumin and immunoglobulin G (IgG) decreased by 42 +/- 7 and 44 +/- 10%, ...

Filtrability of a suspension of polymorphonuclear leukocytes (PMNs) was examined in a Nuclepore membrane filtration system utilizing a gradually reduced pressure difference with or without an additional negative pressure. The filtration process was continuously recorded using a TV-video system for data analysis. The PMN content in the filtrate was directly ...

The maximum value of capillary filtration coefficient (CFC) in maximally vasodilated cat skeletal muscle is disputed. It was hypothesized that the wide range of reported values was caused by the inability of gravimetric and volumetric measurements of tissue volume to separate transcapillary filtration from vascular volume changes. Consequently, we developed ...

The present study examines the influence of two angiotensin converting enzyme (ACE) inhibitors, perindopril and captopril, on renal plasma flow and on autoregulation of glomerular filtration in anaesthetized rats during reduction of renal perfusion pressure to 100, 90 and 80 mmHg. Groups 1 and 3 had a normal sodium intake ...

The tubuloglomerular feedback (TGF) mechanism was evaluated in the nonclipped kidney of Goldblatt hypertensive rats from both stop flow pressure (SFP) and single nephron glomerular filtration rate (SNGFR) responses to step increases in late proximal perfusion rate from 0 to 40 nl/min. During control conditions, increases in late proximal perfusion ...

Calcium antagonists decrease the ability of the kidney to autoregulate renal blood flow (RBF) and glomerular filtration rate (GFR). Therefore, when afferent renovascular resistance is elevated, as in essential hypertension, there is a resultant increase in RBF and GFR with the administration of calcium antagonists. These agents also induce a ...

Systemic hypertension complicates the course of most patients with chronic renal failure and accelerates the progression of experimental and clinical glomerular disease. Based on recent experimental studies, it is suggested that at similar levels of systemic hypertension, glomerular injury only develops when pre-glomerular resistances are ineffective, thus allowing the development ...

The pathophysiology of radiographic contrast media-induced acute renal failure is unclear. Different causes are suggested, including hypertonicity, charged molecules, and toxicity of the media. This study deals with hemodynamic changes after injection of contrast media of high osmolarity iohexol, and metrizoate. Proximal tubular free-flow and stop-flow pressure (Psf), (the latter ...

Systemic hypertension is both the cause and the consequence of renal disease. Experimental studies suggest that the adverse effects of systemic hypertension on the progression of renal disease may depend upon the intraglomerular hemodynamic consequences. Systemic hypertension accompanied by afferent arteriolar vasoconstriction is associated with normal glomerular capillary pressure and ...

More than half of the United States population over 65 years of age has essential hypertension. In 1984, there were 10 million elderly hypertensive persons and this number will reach 25 million in the near future. These patients are at high risk for congestive heart failure, stroke, heart attack, and ...

Micropuncture experiments were performed in volume-expanded rats to better define the nephron segments in which changes in renal perfusion pressure inhibit tubular reabsorption. Neural influences on the kidney were eliminated by renal denervation, and plasma levels of vasopressin, aldosterone, corticosterone, and norepinephrine were maintained at fixed levels by i.v. infusion. ...

In anaesthetized beagles, saralasin, phentolamine, 1-penicillamine-2-O-methyl-tyrosine-8-arginine-vasopressin and SCH 23390, a DA1 antagonist, were infused into the left renal artery (i.r.a.) and indomethacin and aprotinin intravenously (Group 1). In Groups 2 and 3, i.r.a. infusion of two chemically different putative leukotriene (LT) antagonists, FPL 55712 (100 micrograms/kg/min) and LY 171883 (500 ...

Cardiac output (CO), renal blood flow (RBF), and glomerular filtration rate were measured in 29 young patients with borderline hypertension, in comparison with 26 normotensive controls of the same age and sex. In patients with borderline hypertension, both CO and RBF were significantly increased, whereas the RBF/CO ratio remained within ...

In order to assess the determinants of renal function deterioration induced by angiotensin-converting enzyme inhibition (ACEI) in renovascular hypertension, studies were performed in patients with bilateral stenosis (BS; n = 12) and stenosis of a solitary kidney (SK; n = 10). Acute administration of captopril was associated with a consistent ...

To determine how liquid accumulation affects extra-alveolar perimicrovascular interstitial pressure, we measured filtration rate under zone 1 conditions (25 cmH2O alveolar pressure, 20 or 10 cmH2O vascular pressure) in isolated dog lung lobes in which all vessels were filled with autologous plasma. In the base-line condition, starting with normal extra-alveolar ...

Passive Heymann nephritis (PHN), a model of experimental membranous nephropathy produced by the administration of anti-Fx1A antibody, was studied by micropuncture measurement of glomerular hemodynamics and by assessment of immunologic and morphologic findings. The effect of complement depletion on these parameters was evaluated by administering cobra venom factor. Five days ...

1. Capillary blood pressure was measured in man using a dynamic servo-nulling system and direct micropuncture. This enabled assessments of the normal variations in pressure which influence fluid filtration and reabsorption. 2. Seventy-eight capillaries in 19 subjects were punctured in one of three positions around the capillary loop with the ...

Extracellular fluid volume expansion is known to produce exaggerated natriuresis in essential hypertension. In order to assess the role of hemodynamic and intrarenal physical factors upon natriuretic response to central volume expansion, two hour water immersion (WI) experiments were made in six uncomplicated essential hypertensives and six normotensive healthy controls. ...

Glomerular hemodynamics measurements in rats with experimental membranous nephropathy [passive Heymann nephritis (PHN)] have demonstrated that the appearance of proteinuria 5 days after administration of anti-Fx1A antibody is temporally related to changes in the glomerular ultrafiltration coefficient (LpA). Previous studies in other models of glomerular injury have suggested a significant ...

Acute hypertension was previously shown to cause partial inhibition of proximal tubule fluid reabsorption in perfused tubules in the rat. If the inhibition also occurs in unobstructed tubules receiving native glomerular filtrate, hypertension should increase end proximal flow rate despite autoregulation of glomerular filtration rate (GFR). We tested this prediction ...

In vitro and mathematical models of continuous arteriovenous hemofiltration (CAVH) have been developed. Human erythrocytes resuspended in normal saline containing 5% bovine albumin were used to perfuse the circuit from a gravity driven pressure source. Membrane hydraulic permeability was observed to decline from 31.2 x 10(-5) +/- 11.9 x 10(-5) ...

Few studies exist on the interaction of diuretics and angiotensin-converting enzyme inhibitors in patients with chronic heart failure. Twelve subjects with heart failure were studied before and after their usual oral dose of frusemide in random order on consecutive days during fixed sodium, potassium and water intake. Patients then received ...

Experiments were performed on 23 dogs to assess the effect of splanchnic pooling on renal hemodynamics and Na retention. When the thoracic duct pressure was raised to 40 cm H2O (HTDP), liver interstitial pressure rose from 9.0 +/- 0.4 to 19.8 +/- 1.1 cm H2O. Simultaneously, glomerular filtration rate (GFR) ...

The essential component of pulmonary emphysema is destruction of alveoli. Because capillaries make up much of the alveolar wall, it has been a long-held opinion that capillary loss in this disease parallels the loss of other elements of the alveolar septum. Yet the nature of the damage to capillaries and ...