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Results 451 - 500 of 948
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Melis M S - - 1991
A study conducted on rats using classical clearance techniques and arterial pressure measurements showed that stevioside from Stevia rebaudiana leaves produced a fall in systemic blood pressure, as well as diuresis and natriuresis per milliliter of glomerular filtration rate. Verapamil tended to increase the renal and systemic effects of stevioside. ...
Pelayo J C - - 1991
In the present micropuncture study, the autoregulation of glomerular capillary hydrostatic pressure (PG) in Munich-Wistar rats 24 h after 75% nephrectomy (Nx) or sham operation (Sh) was investigated. The effect of varying renal perfusion pressure (RPP) on paired determinations of directly measured PG was evaluated in glomeruli of nephrons in ...
Leyssac P P - - 1991
The dynamics of intrarenal pressures, early distal tubular fluid conductivity (EDC), and renal flood flow (RBF) were studied in rats given acetazolamide (ACZ), an inhibitor of proximal reabsorption. Glomerular filtration rate (GFR) and end-proximal flow were estimated by clearances of 51Cr-EDTA and lithium. Proximal tubular pressure (Pprox) increased initially by ...
Kawata T - - 1991
Our results revealed that renal blood flow (RBF) increased during both isooncotic and hypooncotic plasma expansion by 4% of body weight (BW). Tubuloglomerular feedback (TGF) sensitivity assessed by the measurement of proximal stop-flow pressure at loop perfusion rates of 0 to 40 nl/min and RBF autoregulation were not substantially affected ...
Morsing P - - 1991
The tubuloglomerular feedback (TGF) mechanism was studied in rats with chronic partial ureteral occlusion (hydronephrosis) with the use of the stop-flow pressure techniques and measurements of single nephron glomerular filtration rate. In hydropenic conditions, TGF was normal in hydronephrotic kidneys, but TGF sensitivity and activity increased in response to extracellular ...
Morsing P - - 1991
The role of bradykinin in resetting the tubuloglomerular feedback (TGF) mechanism was studied with the stop-flow technique in control and hydronephrotic Inactin-anesthetized rats. Glomerular function was assessed by measuring stop-flow pressure (Psf); the maximal decrease in stop-flow pressure (delta Psf) with increased loop of Henle perfusion and the perfusion that ...
Maspers M - - 1991
The aim of this study was to evaluate a possible humoral beta 2-adrenergic effect on the capillary pressure autoregulation capacity in cat skeletal muscle during bleeding. For this purpose capillary pressure autoregulation in response to graded decrease in arterial pressure was studied in sympathectomized muscle in the control state, and ...
Lafferty H M - - 1991
To explore the role of systemic hematocrit in the vascular adaptations which characterize desoxycorticosterone-salt hypertension, studies were performed in three groups of rats with uninephrectomy, desoxycorticosterone administration, and 1% saline in the drinking water. One group received recombinant human erythropoietin to increase hematocrit, and another group was subjected to phlebotomy ...
Anderson S - - 1991
The intrarenal hemodynamic effects of antihypertensive agents vary considerably, and these microcirculatory effects may contribute to long-term structural sequelae in the setting of chronic renal disease. To investigate the consequences of blood pressure reduction with calcium antagonists, 5/6 nephrectomized Munich-Wistar rats underwent baseline determinations of mean arterial pressure, whole kidney ...
Sevick E M - - 1991
The net transvascular filtration rate, JF (ml/min/100 g), in an isolated, RBC-free perfused R3230AC mammary adenocarcinoma tumor was measured using a gravimetric method whereby changes in tissue weight over time were monitored. From the gravimetric measurements of JF following changes in venous pressure, the capillary filtration coefficient (ml/min/mm Hg/100 g) ...
Tanita T - - 1991
We reported a new way for estimating filtration variables: K(filtration coefficient), Ppmv (perimicrovascular pressure) and sigma (protein reflection coefficient), from 3 different measurements of weight gain at two protein concentrations of perfusate (Cmv) and at two vascular pressures (Pvasc). We used the Starling equation for calculating those variables using two ...
Sekse I - - 1991
We have earlier shown that there is an immediate fall in renal blood flow (RBF) and glomerular filtration rate (GFR) during induction of passive Heymann nephritis (PHN) by infusion of rabbit antibodies towards rat renal brush-border antigens (anti-Fx1A). To investigate the role of complement activation in this stage of the ...
MacDonald T M - - 1991
The effects of oral doses of the dopamine antagonist antiemetics metoclopramide and domperidone on baseline and dopamine stimulated renal function and systemic haemodynamics were assessed in a placebo controlled crossover study in 9 healthy volunteers. Metoclopramide did not change baseline ERPF, GFR or FF over 2 h post dosing but ...
Kimura G - - 1991
The effects of a calcium-entry blocker, nicardipine, on intrarenal hemodynamics were studied in essential hypertension. A 4-week study was performed in eight patients with essential hypertension who were given a regular sodium diet in the first and third weeks, and a sodium-restricted diet in the second and fourth weeks. Nicardipine, ...
Mercatello A - - 1991
Microalbuminuria is known to increase in various diseases with potential repercussion on the kidneys and indicates an increase in glomerular intracapillary pressure or changes in permeability characteristics. In this study, we measured whether albumin excretion is affected in patients undergoing anesthesia and surgery, which are both known to induce dramatic ...
Batra S - - 1991
The geometry of capillary networks was examined in pressure-overloaded hypertrophic rat myocardium. All hearts were exposed to a staining protocol that distinguished the arteriolar (AC) and venular (VC) regions of capillaries. In control hearts, the triangulation method (one-dimensional distance between neighboring capillaries) and the domain method (two-dimensional area surrounding capillaries) ...
Schneider J - - 1991
The prostacyclin analogue taprostene protects against lethal endotoxemia in rats. In the present study, the effects of taprostene on endotoxin-induced cardiovascular, pulmonary and renal alterations have been investigated. In anesthetized rabbits, infusion of 0.5 mg/kg Escherichia coli lipopolysaccharide i.v. over 30 min produced systemic hypotension, pulmonary hypertension, and decreases in ...
Neumann H A - - 1991
Lipodermatosclerosis is a sign of severe chronic venous insufficiency. In this stage of CVI one can find capillary leakage of water and plasmaproteins which results in a higher capillary filtration rate. In skin biopsies the result of this process can be seen as a pericapillary halo. The group of Burnand ...
Schmieder R E RE Department of Medicine, University of Bonn, Bonn-Venusberg, Federal Republic of - - 1990
In 111 patients with essential hypertension (World Health Organization stage I or II), we examined the relationship between renal hemodynamics and left ventricular hypertrophy. Left ventricular structure was determined by two-dimensional guided M-mode echocardiography, renal blood flow by iodine I 131 aminohippuric acid clearance, and glomerular filtration rate by creatinine ...
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% ...
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