In this study we extend the analysis of the preceding two studies [J. L. Stephenson, J. F. Jen, H. Wang, and R. P. Tewarson. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F698-F709, 1995; and J. F. Jen, H. Wang, R. P. Tewarson, and J. L. Stephenson. Am. J. ...

RATIONALE AND OBJECTIVES: Renal perfusion can be evaluated with first-pass study of superparamagnetic iron oxide particles (SPIO). We applied this technique to a unilateral renal hypoperfusion model in rabbits. METHODS: Turbo fast low-angle shot sequences (acquisition time = 440 msec), after bolus injection of SPIO (100-140 mumol/kg iron), were performed ...

We review evidence supporting the conclusion that renal dysfunction underlies the development of all forms of hypertension in humans and experimental animals. Indexes of global renal function are generally normal in the early stages of most genetic forms of hypertension, but renal function is clearly impaired in long-established hypertension. Studies ...

The direct adreno-renal vascular connection allows precise control of the kidney function by hormones produced by the adrenal gland, without any significant changes in their content in the whole blood. The purpose of the present study is to investigate the effect of the increased blood flow through the vascular network ...

This study examined whether nitric oxide synthesis blockade or potentiation (with N omega-nitro-L-arginine methyl ester [L-NAME] or N-acetylcysteine, respectively) can shift the relations between sodium excretion, papillary blood flow, and renal perfusion pressure. Papillary blood flow was measured by laser Doppler flowmetry. A low dose of L-NAME (3.7 nmol/kg per ...

OBJECTIVE: To determine the effect of intraperitoneal sepsis on the systemic and renal actions of the continous infusion of epinephrine or dopamine, and during the concurrent administration of both drugs. DESIGN: Prospective, randomized study. SETTING: Laboratory at a university hospital. SUBJECTS: Seven conscious, chronically catheterized, adult merino sheep. INTERVENTIONS: Epinephrine ...

Cardiac arrhythmia can be a serious complication during general anesthesia. On the other hand, there is a need for general anesthesia of patients suffering from cardiac arrhythmias and using antiarrhythmic drugs. The aim of the present experiments was to establish the way in which procainamide, N-acetyl-procainamide, verapamil and propranolol influence ...

Renal insufficiency following periods of infrarenal aortic cross clamping has been reported by some investigators but not by others, and conflicting views have been expressed concerning the ability of renal autoregulation to overcome the adverse circulatory effects of cross clamping. The object of this study was to examine the blood ...

The effects of 1-2 h of hypothermia at 28 degrees C and rewarming on renal function were investigated in anaesthetized rats, using conventional clearance methods and the micropuncture technique. Renal blood flow (RBF) decreased from 7.3 +/- 0.51 mL min-1 at 37.5 degrees C (control) to 4.0 +/- 0.47 at ...

Renal blood flow is reduced in patients with chronic respiratory failure caused by chronic obstructive pulmonary disease (COPD), and changes in renal hemodynamics are likely to be important in the pathogenesis of the edematous state of cor pulmonale. We therefore examined the hypothesis that this renal vasoconstriction is reversible by ...

The effect of chronic intravenous infusion of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 8.6 mg.kg-1.day-1) on blood pressure, intrarenal blood flow distribution, and sodium and water balance was studied in conscious rats. On the 1st day of intravenous L-NAME infusion, renal medullary blood flow was reduced by 22%, ...

Renal function is intimately dependent on renal blood flow. Alterations in either total or regional renal blood flow have major consequences for renal function. Through homeostatic mechanisms the kidneys are able to maintain relatively stable rates of flow over a wide range of perfusion pressures. A combination of neural, endocrine, ...

A retrospective analysis of 34 patients of obstructive renal failure, initially managed by percutaneous nephrostomy was performed. Pre procedure blood biochemical profile was compared with upto one week follow-up of blood chemistry. There was a decline of 71.1% and 56.08% (P-values 0.0001 and 0.0028) in the mean values of serum ...

The effects of acute and chronic inhibition of endothelium derived relaxing factor (EDRF/NO) synthesis were investigated on the intrarenal blood flow in anaesthetized rats. N omega-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg) was used for inhibition of NO-synthase. In acute experiments L-NAME was infused, while in chronic experiments L-NAME (4-day pretreatment) ...

To examine the utility of Doppler ultrasound in assessing renal hemodynamics, we investigated the effects of dopamine and dobutamine on renal blood flow using Doppler ultrasound technique and conventional clearance tests in 7 healthy volunteers. After visualization of arterial blood flow in the right renal hilus by two-dimensional color flow ...

To study hemodynamic effects on intrarenal oxygenation, O2 microelectrodes were inserted into rat kidneys. In a previous study [M. Brezis, Y. Agmon, and F. H. Epstein. Am. J. Physiol. 267 (Renal Fluid Electrolyte Physiol. 36): F1059-F1062, 1994], we showed that tubular metabolism is a major determinant of intrarenal oxygenation, in ...

To study renal cortical and medullary oxygen tensions, we used sensitive Clark-type O2 microelectrodes, inserted by micromanipulators into the cortex and medulla of kidneys of anesthetized rats. As previously reported, under basal conditions, medullary PO2 was significantly lower than cortical PO2. Furosemide, which inhibits reabsorptive transport in the medullary thick ...

The effects of a selective agonist for endothelin ETB receptors, Suc-[Glu9,Ala11,15]endothelin-1-(8-21), IRL1620, on renal hemodynamics and urine formation were studied in anesthetized dogs. Intrarenal arterial infusion of IRL1620 at a dose of 50 ng/kg/min increased renal blood flow from 3.37 +/- 0.30 (mean +/- S.E.) to a maximal value of ...

The renal contribution to the amino acid-induced whole body thermogenesis was examined. Using indirect calorimetry and catheter techniques, pulmonary and renal oxygen uptake and blood flow, blood temperatures, and net renal exchange of amino acids, glucose and lactate were measured in eight healthy men before and during 3 h of ...

Haemodynamic responses to slow (0.7 ml kg-1 min-1) haemorrhage were investigated in eight adult conscious sheep, fitted with permanent ultrasonic flow probes around the renal and femoral artery. The haemorrhage was continued until the mean systemic arterial pressure (MSAP) suddenly dropped to about 50 mmHg. The spontaneous recovery was followed ...

The luminal membrane of collecting duct cells, especially the intercalated cells, is normally exposed to active kallikrein. This is the consequence of the specific localization of this renal enzyme in the connecting tubule cells and its principal route of secretion being into the tubular lumen. It is conceivable that kallikrein ...

In urethane-anesthetized male Sprague-Dawley rats, microinfusion of N-methyl-D-aspartate (NMDA) into the area postrema (AP) at the dose of 10 ng produced significant decreases in mean arterial pressure (MAP) (-26 +/- 5 mmHg), heart rate (HR) (-34 +/- 6 bpm), renal blood flow, mesenteric blood flow, and iliac vascular resistance. In ...

The effects of a Ca2+ entry blocker, nifedipine, and a putative intracellular Ca2+ release inhibitor, 8-(N, N-diethylamino) octyl-3,4,5-trimethoxybenzoate (TMB-8), on mesenteric vasoconstriction, induced by angiotensin II, were examined in anesthetized dogs. Injection of angiotensin II (5 and 10 ng/kg) into the mesenteric artery decreased the mesenteric blood flow, which was ...

Whole blood and plasma serotonin (5-HT), its major metabolite--5-hydroxyindoleacetic acid (5-HIAA), renal cortical blood flow, serum creatinine and whole blood cyclosporine A (CyA) levels were investigated in rats administered with CyA at a dose of 5 mg/kg b.w. or 10 mg/kg b.w. for 14 consecutive days. Serum creatinine remained unaltered ...

To investigate the effects of an angiotensin II type 1 receptor antagonist (CV-11974) on renal blood flow and renal sympathetic nerve activity compared with a calcium antagonist (nicardipine), we measured both parameters in conscious spontaneously hypertensive rats aged 13 to 15 weeks. One to 2 days after surgery, CV-11974 (n ...

Human radiocontrast nephrotoxicity is predicted by the presence of multiple risk factors, often associated with compromised renal circulation. To produce a simple model of radiocontrast nephropathy, rats were pretreated with indomethacin and N omega-nitro-L-arginine methyl ester (L-NAME, to inhibit nitric oxide synthesis) before the administration of iothalamate. Acute renal failure ...

Alterations in renal blood flow distribution may occur in a variety of pathophysiologic situations; however, quantification of global and regional renal blood flows has been limited because of the lack of reliable, noninvasive techniques. To determine the feasibility of flow measurements with electron-beam computed tomography (EBCT), six anesthetized dogs were ...

Computed duplex sonography was used to examine the renal arteries in 36 hypertensive children and adolescents (ages 4-17 years) with arterial hypertension of either renal or non-renal origin. Time-averaged flow velocities, maximum blood flow velocities as well as absolute renal blood flow and renal blood flow per gram kidney weight ...

OBJECTIVE: To gauge the influence of renovascular resistance changes on blood flow velocity pulsatility in kidneys of hypertensive patients by means of the ultrasonic colour and pulsed-wave Doppler method, since we have previously shown in normotensive subjects that the blood flow velocity pulsatility in renal interlobar arteries varies with changes ...

To investigate whether changes in renal blood flow induced by nondepressor doses of L-arginine, the precursor of nitric oxide, are mediated by a sympathetic neural mechanism, we examined the following in conscious rabbits: (1) the effects of intravenous infusion of L- or D-arginine (15 to 200 mumol/kg per minute) on ...

The effects of peritoneal insufflation with carbon dioxide on hepatic and renal blood flow have not been reported hitherto. We evaluated these effects in a porcine model of abdominal laparoscopic surgery. Seven anesthetized pigs underwent peritoneal insufflation in a step-wise manner to create intraabdominal pressures of 6, 12, 18 and ...

The arterial blood pressure, a physiological variable on which all renal excretory processes depend, fluctuates over a wide range of amplitudes and frequencies. Much of this variation originates in nonrenal vascular beds to support nonrenal tasks, and the fluctuations provide a noisy environment in which the kidney is obliged to ...

We have tested the effects of weightlessness on renal function in one subject who flew the recent week-long Russian-German MIR'92 space mission. Urine flow, renal sodium excretion, and the excretion of urodilatin were measured during the first and last days of the flight. Our results demonstrated, in contrast to expectations, ...

We studied fetal lambs to define the renal pathophysiology of chronic in utero partial bladder outlet obstruction. These fetal lambs, 115 to 120 days gestation (term = 145 days), underwent urethral ligation, placement of a urachal catheter and positioning of an ultrasonic flow transducer around the left renal artery. Partial ...

There is at present no noninvasive method that reliably measures blood flow in the poorly functioning renal allograft. The present study was designed to evaluate phase-contrast cine magnetic resonance imaging (PC-cine-MRI) for this purpose. We recruited for study 18 patients who had received kidney transplants 13-66 months earlier from closely ...

Fast computed tomography (CT) is one of the few methods available to measure cortical and medullary renal blood flow (RBF) directly. Because these measurements are complicated by passage of the contrast medium into extravascular compartments, we used the residual opacity following the vascular blush as an index to account for ...

OBJECTIVE: Chronic congestive heart failure (CHF) was induced in rabbits with doxorubicin in order to evaluate: (1) haemodynamic and regional blood flow responses to propofol anaesthesia; (2) modification of these cardiovascular responses with background intravenous infusions of enalaprilat or dopexamine. METHODS: Rabbits received either doxorubicin, 2 mg.kg-1 weekly intravenously for ...

The carbonic anhydrase inhibitor acetazolamide (ACZ) inhibits the absolute rate of proximal reabsorption (APR), causes a reduction in glomerular filtration rate (GFR), and activates the tubuloglomerular feedback mechanism (TGF) resulting in afferent vasoconstriction. The quantitative importance of the afferent vasoconstriction for the reduced GFR was tested by addition of a ...

The pharmacokinetics of azosemide were evaluated simultaneously using both arterial and venous plasma data in six rabbits after a rapid 5 s intravenous bolus dosing. Initial arterial to venous ratios at 5 s after injection were the highest with values of 81.1, 67.3, 58.7, 530, 2660, and 10.5 for rabbits ...

The effects of chronic nitric oxide inhibition in the renal medulla on renal cortical and medullary blood flow, sodium balance, and blood pressure were evaluated in conscious uninephrectomized Sprague-Dawley rats. During a 5-day renal medullary interstitial infusion of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 120 micrograms/h) in saline ...

STUDY OBJECTIVES: To evaluate the decomposition of sevoflurane in soda lime during prolonged sevoflurane anesthesia in humans. To evaluate for evidence of renal or hepatotoxicity as a result of exposure to these sevoflurane degradation compounds. DESIGN: Prospective evaluation in healthy volunteers. SETTING: Clinical research unit and postanesthesia care unit of ...

The objective of this study was to determine the dose-response effects of epinephrine, given by systemic intravenous infusion to the halothane-anesthetized newborn piglet, on renal blood flow, mean arterial blood pressure, and renal vascular resistance. Seven newborn piglets were acutely instrumented. A transit-time ultrasound flow probe was placed around the ...

1. Evidence indicates that nitric oxide (NO) exerts a paracrine influence in the renal medulla. Increases in papillary blood flow are thought to be an important determinant of the renal response to extracellular volume expansion. Therefore, in the present study, we have evaluated the role of NO in mediating papillary ...

An animal model was established to study the effects of elevated intra-abdominal pressure (IAP) on systemic and renal hemodynamics during laparoscopy. In a pilot study in five dogs, we simultaneously recorded carotid artery blood flow (CABF), carotid artery blood pressure (CABP), inferior vena caval pressure (IVCP), renal parenchymal blood flow, ...

In vivo fluorescence microscopy was used in experimental studies of renal cortical microcirculation in mice. The effects of i.v. infusions of mannitol and iohexol were studied in normal and obese/hyperglycemic mice and in mice with streptozotocin-induced diabetes mellitus. All infusions produced marked effects on the distribution and velocity of cortical ...

1. The study examines whether intracerebroventricular (ICV) infusion of atrial natriuretic peptide (human ANP,1-28) influences renal electrolyte and water excretion, vasopressin release, renal and femoral blood flows in conscious ewes. The blood flow was measured by chronically implanted ultrasonic flow probes. 2. ICV infusion of ANP(1-28) at 25 pmol/min for ...

The present study evaluated the role of endogenous P-450 metabolites of arachidonic acid (AA) on autoregulation of renal blood flow in rats. Whole kidney and cortical blood flows were well autoregulated when renal perfusion pressure was varied from 150 to 100 mmHg. Infusion of 17-octadecynoic acid (17-ODYA) into the renal ...

The influence of 10 min intracarotid (i.c.) and intravenous (i.v.) infusions of angiotensin II (Ang II; 20 pmol kg-1 min-1) on carotid blood pressure (cBP) and renal blood flow (RBF) was studied in unanaesthetized ewes without and with pre-treatment with the alpha 1- and beta-adrenoceptor blocker labetalol. RBF was also ...

The studies of the present thesis are focused on the systemic and renal effects of low (physiological) doses of ANF, and describe a few of the first studies in man.

Inner medullary blood flow has been found to remain nearly unchanged during postischemic renal failure, despite a severely disturbed perfusion in the outer medulla. In order to elucidate this discrepancy, rats were subjected to 1 h left renal artery occlusion and 1 h reflow. The blood plasma was then labeled ...