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Results 451 - 500 of 929
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Heller J - - 1990
Twenty-four hours after 90 min clamping of the left renal artery in dogs, the glomerular filtration rate (GFR) was decreased in the whole kidney (0.34 ml.min-1g KW-1 [KW = Kidney weight] vs 0.64 in contralateral unclamped kidney) just as in the single nephron (SNGFR, 19.7 vs 51.8 nl.min-1). Renal blood ...
Miller P L - - 1990
The effect of tissue preparation on glomerular volume in normal rats was assessed. In group 1 rats (N = 8), kidney tissue was obtained by immersion-fixation of needle biopsy cores and excised slices from the left kidney and by perfusion-fixation of the remaining right kidney at close to ambient arterial ...
Blantz R C - - 1990
Increasing evidence indicates the existence of a complex interplay between the angiotensin and adrenergic nervous systems within the kidney. Since both of these vasoconstrictor systems are integrally involved in the maintenance of systemic blood pressure and fluid and electrolyte homeostasis, it is not surprising that each might influence the other ...
Davis J M - - 1990
Central to the assumption that glomerular capillary pressure (Pgc) can be equated with the sum of arterial oncotic pressure (pi art) and the pressure in a blocked proximal tubule ("stop flow" pressure, Psf) is that filtration ceases in the blocked nephron. Should filtration not cease, but continue at a rate ...
Mall G - - 1990
Stereological investigations on myocardial capillaries provided evidence that the common estimator of capillarity, the capillary density (i.e., number of capillary profiles per unit transverse sectional area), underestimates the true capillary supply since the capillary axes are not oriented perfectly in parallel to the myofiber axes. Recently, we studied the "true" ...
Cupples W A - - 1990
Previous models, assuming constant reabsorption in the proximal tubule, have shown that tubuloglomerular feedback (TGF) can explain only a fraction of glomerular filtration rate (GFR) and renal blood flow autoregulation. Increased arterial pressure inhibits proximal tubule fluid reabsorption, an effect that should increase the efficacy of TGF because of the ...
Hellberg P O - - 1990
Trapping of red blood cells (RBCs) in renal medulla vasculature in postischemic acute renal failure (ARF) was found to depend upon the length of the ischemic period. Thus trapping occurred after 45 minutes but not 25 minutes of ischemia. By prior hemodilution to a hematocrit (hct) of 30%, RBC trapping ...
Quilley C P - - 1990
A metabolite of arachidonic acid, 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), which can be formed either in the 12-S or 12-R configuration, has a diversity of biological actions and is generated by a number of tissues including the renal glomerulus and the vasculature. As the two isomers have been shown to differ in ...
Rosenberg M E - - 1990
The purpose of this study was to examine the course of residual glomerular function in two models of renal ablation both with equivalent degrees of nephron reduction (1 1/3 nephrectomy). The remnant group underwent right nephrectomy and infarction of one third of the left kidney, yielding constant proportions of remnant ...
Lee H G HG Department of Biochemistry, School of Medicine, University of Tennessee, Memphis - - 1990
Glucose was covalently coupled to aminopropyl derivatized silica of various pore sizes. The reaction most likely involved Schiff's base formation between the aldehyde of glucose and the amine on the silica which was then reduced with NaCNBH3. This glucose-silica behaved as a nearly ideal molecular sieving support for the high-pressure ...
Källskog O - - 1990
We sought to determine whether tubuloglomerular feedback (TGF), activated from one nephron, affects other arterioles derived from the same cortical radial artery. Surface nephrons supplied by a single cortical radial artery were identified by injecting Ringer solution containing Fast Green from a narrow-gauge polyethylene catheter inserted via a lumbar artery ...
Morsing P - - 1990
From previous studies on hydronephrotic rats in our laboratory, an increased sensitivity of the tubuloglomerular feedback (TGF) mechanism was found during extracellular volume expansion (VE). In contrast, the mechanism resets to a lower sensitivity during VE in control animals. The resetting in hydronephrotic rats was reversed by blocking the thromboxane ...
Dworkin L D - - 1990
To examine the effects of dietary calcium supplementation on systemic and renal hemodynamics and glomerular injury in experimental hypertension, rats with desoxycorticosterone-salt hypertension were fed either standard chow, containing 1% calcium by weight, or chow supplemented with calcium carbonate to achieve a calcium content of 2% by weight. Ingestion of ...
Shibata T - - 1990
A 41-year-old Japanese woman with lipoprotein glomerulopathy is reported. The patient presented with nephrotic syndrome, hyperlipoproteinemia and an increased level of plasma Apo E. The damaged glomeruli showed various degrees of capillary dilatation and accumulation of some material-often showing stratification, along with mesangial proliferation and mesangial interposition. The accumulated material ...
Valvo E - - 1990
1. Urinary albumin excretion and the effect of an acute oral protein load (a meat meal) on glomerular filtration rate ('renal functional reserve') were evaluated in 15 essential hypertensive patients with preserved renal function and compared with 12 normal subjects. 2. Seven patients had microalbuminuria (greater than 30 mg/day) that ...
Kinoshita Y - - 1990
Although urinary sodium excretion is positively influenced by acute changes in renal perfusion pressure, micropuncture studies show highly conflicting results concerning the response of superficial proximal tubule sodium reabsorption to changes in renal perfusion pressure. In the present study, the changes of superficial proximal reabsorption to decreased and increased renal ...
Clark E S - - 1990
The effects of intravenous infusion of endotoxin for 30 minutes at a cumulative dosage of 0.03 micrograms/kg on average carotid arterial pressure, and on average arterial pressure, capillary pressure, venous pressure, total vascular resistance, precapillary resistance, postcapillary resistance, and capillary filtration coefficient in the jejunum were compared to the effects ...
Tanita T - - 1990
The filtration variables, K (filtration coefficient), Ppmv (perimicrovascular pressure) and sigma (reflection coefficient), were estimated independently in previous reports using the Starling equation or the micropuncture method. We used matrix algebra to estimate these variables simultaneously. We measured filtration rate (Q) by a gravimetric method in isolated rat lung lobes ...
Pollock D M - - 1990
The effect of renal vasodilation produced by the dopamine DA1-receptor agonist, fenoldopam (SKF-82526), on tubuloglomerular feedback (TGF) activity and the autoregulation of renal blood flow (RBF) was determined in euvolemic rats. Fenoldopam (2.5 micrograms.kg-1.min-1 iv) increased RBF by 17% (electromagnetic flow probe) while glomerular filtration rate (GFR) was unchanged; mean ...
Heller J - - 1990
Kidney function of beagles fed a constant amount of food containing 3 mmol sodium.kgbodywt-1.day-1, and anaesthetized with pentobarbitone was investigated by clearance and micropuncture techniques during an intrarenal infusion of saline or the calcium antagonists verapamil (VER, 4 micrograms.kgbodywt-1.min-1) or nifedipine (NIF, 0.3 microgram.kgbodywt-1.min-1). Neither drug changed the mean arterial ...
Weinstein A M - - 1990
A nonelectrolyte model of proximal tubule epithelium has been extended by the inclusion of a compliant tight junction. Here "compliance" signifies that both the junctional salt and water permeability increase and the salt reflection coefficient decreases in response to small pressure differences from lateral interspace to tubule lumen. In previous ...
Schnermann J - - 1990
Experiments were performed in anesthetized rats to study the effect of the selective adenosine1 (A1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX) on tubuloglomerular feedback (TGF) responses assessed as the maximum change of stop-flow pressure (PSF). Compared with control, PSF responses were reduced during luminal application of CPX at 10(-4) and 10(-5)M (-4.9 ...
Remuzzi A - - 1990
The effect of enalapril on glomerular hemodynamics and permselectivity and on subsequent sclerosis was studied in male MWF/Ztm rats which spontaneously develop proteinuria and glomerular structural damage. Untreated group 1 and enalapril-treated group 2 (50 mg/liter, in the drinking water) underwent micropuncture studies after 2 mo of observation. After the ...
Persson P B - - 1990
The effects of a moderate reflex activation of the sympathetic nervous system on renal blood flow (RBF) and glomerular filtration rate (GFR) were studied in 29 experiments on seven conscious foxhounds. Autoregulation parameters were derived by a stepwise reduction of renal artery pressure of 10-mmHg decrements. An occlusion of both ...
Jaramillo-Juárez F - - 1990
1. The effects of reduction in renal blood flow (RBF) on urinary acidification and proximal tubule H+ ion secretion were studied after partial aortic clamping in rats. 2. Acute reduction of the renal perfusion pressure (from 109 +/- 3.88 to 77.4 +/- 1.05 mmHg) decreased both inulin and PAH (p-aminohippurate) ...
Pollock D M - - 1990
The effect of atrial natriuretic factor [ANF-(1-28); 0.25 microgram.kg-1.min-1] on tubuloglomerular feedback (TGF) and the efficiency of renal blood flow (RBF) autoregulation was determined in anesthetized euvolemic rats. In microperfusion studies, ANF dramatically inhibited (greater than 80%) feedback-mediated decreases in single-nephron glomerular filtration rate (SNGFR) and stop-flow pressure (Psf) when ...
Kriz W - - 1990
Glomerular capillaries are perfused at a high hydraulic pressure. Since the capillary mesangium interface presents no morphologically apparent pressure barrier, it is suggested that the hydraulic pressure in the mesangium may also be high. This paper analyzes the structures in the glomerular tuft that are capable of counteracting the distending ...
Kimura K - - 1990
Renal arteriolar diameters were measured, using microvascular resin casts, in two hyperfiltration models of rats: the remnants kidney of subtotal nephrectomy (NX) and streptozotocin-induced diabetic kidney (DM). In the NX, the blood pressure was elevated, urinary protein excretion was markedly increased and glomeruli were severely damaged. In the DM, although ...
Carmines P K - - 1990
Videomicroscopic and micropuncture techniques were utilized to determine segmental microvascular responses of in vitro blood-perfused juxtamedullary nephrons to step changes in renal arterial perfusion pressure (PP). At a PP of 104 +/- 2 mmHg, inside diameters of arcuate arteries (ARC), interlobular arteries (ILA), and afferent arterioles (AFF) averaged 68.6 +/- ...
Lee M R - - 1990
1. Over the last 5 years we have given intravenous gludopa in man and established its effects on the kidney. 2. At doses of 12.5 to 100 micrograms kg-1 min-1 it is natriuretic and also tends to increase renal blood flow and glomerular filtration. Despite the natriuresis, plasma renin activity ...
Kauker M L - - 1990
The effect of kallidin (lysyl-bradykinin) on the urinary recovery of sodium-22 was examined in anesthetized, volume-expanded rats. Sodium-22 was microinfused into the lumen of late proximal convoluted tubules with and without kallidin (100 pg/ml). Kallidin enhanced mean sodium-22 recovery from a control of 2.24 +/- 0.29% to 6.22 +/- 1.30% ...
Wolf M B - - 1989
We investigated the effects of elevated venous pressure, Pv, (up to 140 mmHg) on the solvent drag reflection coefficient, sigma f, for protein and on the capillary filtration coefficient, CFC, in the isolated cat hindlimb perfused at constant flow. The perfusate contained 30% cat plasma and the remainder was a ...
Wolfert A I - - 1989
The glomerular dynamic correlates of failed filtration were studied in volume replete rats with established glycerol-induced acute renal failure (ARF). Over one-half of all nephrons formed virtually no filtrate, while the single nephron glomerular filtration rate (SNGFR) of fluid-filled nephrons, measured at the glomerulotubular junction to preclude the possibility of ...
Gade R - - 1989
Microradiography of nephrons in kidneys perfusion-fixed with glutaraldehyde permits examination of large numbers of nephrons. This technique was applied to rabbits between one and 14 days following unilateral ureteral ligation. Kidneys without ureteral occlusion served as controls. By two days after ureteral obstruction there was dilatation of the ducts of ...
Blantz R C - - 1989
Under normal conditions glomerular blood flow and glomerular capillary hydrostatic pressure and hydrostatic pressure gradient are regulated within a narrow range in spite of variations in volume status and blood pressure. Glomerular ultrafiltration rate is normally regulated by the hydrostatic pressure gradient, the systemic oncotic pressure, the rate of nephron ...
Scholey J W - - 1989
The effect of the converting enzyme inhibitor (CEI) enalapril was assessed in Munich-Wistar rats with established adriamycin nephrosis. Rats were given a single dose of adriamycin and one month later divided into four groups matched for albuminuria, blood pressure, and plasma albumin concentration. Groups 1 and 3 remained untreated while ...
Anderson S - - 1989
Clinical and experimental observations suggest an association between hypercholesterolemia and progressive glomerular injury. In the main, most investigators have assumed that hypercholesterolemia induces an atherosclerotic process in the renal microvasculature analogous to that well recognized in larger vessels. The evidence for this line of reasoning is well described in other ...
Gabbai F B - - 1989
Administration of beta-blockers is frequently associated with decreases in both renal plasma flow and glomerular filtration rate (GFR). Tertatolol, a new non-selective beta-blocker, has demonstrated similar systemic effects to other conventional beta-blockers, but tertatolol produces increases in both renal plasma flow and glomerular filtration rate. To evaluate the renal hemodynamic ...
Pelayo J C - - 1989
To evaluate the contribution of beta 1-2-adrenergic receptor stimulation to the regulation of single-nephron glomerular filtration rate (SNGFR), we examined by micropuncture techniques the effects of systemic and intrarenal infusion of isoproterenol on glomerular hemodynamics in plasma volume-expanded Munich-Wistar rats. Isoproterenol infused systemically was consistently associated with an elevation in ...
Thun M J - - 1989
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 ...
Lugon J R - - 1989
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 ...
Dowling G J - - 1989
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 ...
Remuzzi A - - 1989
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 ...
Anderson S - - 1989
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; ...
Morsing P - - 1989
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 ...
Gustafsson D - - 1989
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 ...
Tucker B J - - 1989
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 ...
Frattini P L - - 1989
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 ...
Holstein-Rathlou N H - - 1989
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 ...
Dworkin L D - - 1989
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 ...
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