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At least 19 recordsLinked to original sources
PubMed1995

Assessing renal effects and renal protection.

ASSESSMENT OF RENAL FUNCTION: There are a number of methods of evaluating renal function, including measurements of glomerular filtration, renal plasma flow, tubular function, micro- and macroalbuminuria and urinary sediment. Of these, microalbuminuria, glomerular filtration and renal plasma flow are the most appropriate. RENAL EFFECTS OF CALCIUM ANTAGONISTS: Calcium antagonists have important effects on renal function, including a reduction in renal vasoconstriction, increased renal blood flow and, in some circumstances, reduced protein excretion. In particular, these agents can reverse the mild renal vasoconstriction that is seen in the offspring of hypertensive patients. The renal effects of calcium antagonists have been studied in animal models, where radioimaging techniques have shown a biphasic haemodynamic response. RENAL PROTECTION WITH CALCIUM ANTAGONISTS: Two important beneficial effects of calcium antagonists are prevention of acute renal failure and protection against cyclosporin nephrotoxicity. Calcium antagonists have thus been used therapeutically in renal transplant patients and in patients with acute renal failure secondary to the effects of nephrotoxic agents.

Albuminuria↗
PubMed1991

Characterization of the renal effects and renal elimination of sulotroban in the dog.

The renal effects and renal handling of the nonprostanoid thromboxane receptor antagonist, sulotroban (4-[2-(phenylsulfonylamino)ethyl]phenoxyacetic acid), were characterized in dogs. Sulotroban was infused i.v. at 0.06, 0.2, 0.6 and 1.0 mg kg-1 min-1 (plus prime) for 180 min. Arterial blood pressure was reduced significantly during infusion of the 1.0 mg kg-1 min-1 dosage only. Diuresis, characterized by increases in both fractional and absolute urinary excretion of sodium, potassium, chloride and calcium, and decreases in urine osmolality occurred at each of the sulotroban dosages tested. The renal clearance of sulotroban exceeded the glomerular filtration rate, suggesting renal secretion of sulotroban. The transport maximum for sulotroban secretion was approximately 160 micrograms kg-1 min-1. Renal cortical slices from naive dogs accumulated [14C]sulotroban against a concentration gradient. Sulotroban accumulation was blocked by metabolic inhibitors (dinitrophenol and sodium azide) and inhibitors of organic anion transport (probenecid and p-aminohippurate), but not by inhibitors of organic cation transport (cyanine and tetraethylammonium), suggesting that tubular secretion of sulotroban is mediated by an organic anion transport system. It was concluded that: 1) decreases in blood pressure occurred only after high dosages and were associated with high plasma sulotroban concentrations; 2) diuresis occurred at all dosages and may represent a separate pharmacological action unrelated to thromboxane receptor antagonism; and 3) renal excretion of sulotroban in the dog occurs by both filtration and tubular secretion with secretion occurring via an organic acid transporter.

Animals↗
PubMed1996

99Tcm-MAG3 renal studies: effective renal plasma flow in patients with spinal cord injuries.

To assess whether number of years since time of injury, level or degree of injury, gender or age influence renal function in patients with spinal cord injury (SCI), single and total kidney effective renal plasma flow (ERPF) was measured in 66 patients using 99Tcm-mercaptoacetyltriglycine (99Tcm-MAG3). In approximately 50% of the SCI patients, the single kidney ERPF was less than 250 ml min-1 and total ERPF was less than 500 ml min-1. The single kidney ERPF was worse in female and older SCI patients than in male and younger patients. For total ERPF, age only was a significant factor. Total ERPF was worse in female than in male SCI patients, though this did not reach significance. We conclude that the non-invasive measurement of renal function using 99Tcm-MAG3 is safe and applied easily to SCI patients.

Adult↗
PubMed1992

Renal prostaglandins, effective renal plasma flow and glomerular filtration rate in healthy elderly subjects.

This study tests the hypothesis that the age-associated reduction in glomerular filtration rate (GFR) and the presence of glomerulosclerosis renders effective renal plasma flow (ERPF) prostaglandin dependent. Ten healthy elderly volunteers were studied in a single-blind placebo-controlled manner using indomethacin to suppress the renal prostaglandins. There was no significant difference in ERPF or GFR following indomethacin when compared with placebo. These results suggest that blocking renal prostaglandins does not significantly alter ERPF or GFR in healthy elderly people.

Aged↗
PubMed1991

Use of nonimaging nuclear medicine techniques to assess the effect of flunixin meglumine on effective renal plasma flow and effective renal blood flow in healthy horses.

The effect of flunixin meglumine on renal function was studied in 6 healthy horses by use of nonimaging nuclear medicine techniques. Effective renal plasma flow (ERPF) and effective renal blood flow (ERBF) were determined by plasma clearance of 131I-orthoiodohippuric acid before and after administration of flunixin meglumine. Mean ERPF and ERBF was 6.03 ml/min/kg and 10.7 ml/min/kg, respectively, before treatment and was 5.7 ml/min/kg and 9.7 ml/min/kg, respectively, after treatment. Although ERPF and ERBF decreased after flunixin meglumine administration, the difference was not statistically significant.

Animals↗
PubMed1988

(+)-sulpiride antagonises the renal effects of gamma-L-glutamyl-L-dopa in man.

1. gamma-L-glutamyl-L-dopa (gludopa) was given by intravenous infusion to six healthy salt-replete men on two occasions, with and without pretreatment with (+)-sulpiride. 2. Gludopa increased sodium excretion, glomerular filtration rate and effective renal plasma flow whilst decreasing plasma renin activity. 3. (+)-sulpiride had no significant effect on baseline natriuresis, renal haemodynamics or plasma renin activity, but significantly attenuated the rise in sodium excretion, glomerular filtration rate and effective renal plasma flow produced by gludopa. 4. (+)-sulpiride abolished the acute fall in plasma renin activity seen with gludopa. 5. (+)-sulpiride raised serum prolactin concentration but did not affect the ris in urine dopamine excretion rate caused by gludopa. 6. Gludopa exerts its renal effects by stimulating specific dopamine receptors which are principally of the DA1 subtype.

Adult↗
PubMed1998

Dissociation between the renal effects of angiotensin I and II in sodium-restricted normal subjects.

OBJECTIVE: To determine whether the effects of angiotensin I (AngI) in humans can be explained entirely by its plasmatic conversion to angiotensin II (AngII). METHODS: Ten healthy male volunteers on a sodium-restricted diet were studied on two separate occasions. during which, in random order, AngI or AngII was infused in increasing doses of 0.3, 1 and 3 pmol x kg-1 x min-1. Mean arterial pressure (MAP), effective renal plasma flow (ERPF), glomerular filtration rate (GER), active plasma renin concentration (APRC), AngII, aldosterone (Aldo) and catecholamines were assessed at baseline, after each dose of AngI or AngII and 30 and 60 min after discontinuation of the AngI/AngII infusion. RESULTS: The rise in plasma AngII was significantly less during AngI infusion as compared to AngII infusion (P < 0.05). Changes in MAP, Aldo and GFR, however, were compatible during both infusions. In the kidney, on the other hand, the decrements in APRC and ERPF during AngII infusion exceeded those during AngI (P < 0.05). After cessation of either infusion. AngII concentrations, MAP, ERPF and Aldo returned to baseline levels within 1 h. Renin, however, was still significantly inhibited at that time (P < 0.05). Catecholamines remained virtually unchanged during all experiments. CONCLUSIONS: Our data show that AngI and AngII have similar effects on blood pressure and Aldo, but they differ in their renal effects. The latter may be due to a low renal capacity to convert AngI. The prolonged inhibition of renin release after cessation of the infusions may be caused by reduced renin mRNA expression or by accumulation of AngII in the kidney.

Adult↗
PubMed1979

The renal effects of clonidine in unanesthetized rats.

Clonidine s.c. (0.01-0.3 mg/kg), in unanesthetized rats, caused an initial rise (+20 mm Hg), followed by a continuous fall of BP and a dose-dependent natriuresis and diuresis for up to 2 h. Glomerular filtration rate (GFR) (CIn) increased during the first 20 min, while effective renal plasma flow (ERPF) (CPAH) remained normal. Subsequently, between 20 and 60 min after injection, ERPF (CPAH) decreased considerably while GFR had reverted to its normal value. In saline-infused rats clonidine diuresis was accompanied by an "inappropriate" positive free water clearance. Pentobarbital anesthesia suppressed the initial BP peak and the diuresis. Phenoxybenzamine (1 mg/kg i.v.) was antinatriuretic in saline diuresis; the effect of phenoxybenzamine + clonidine on diuresis and salt excretion represented the sum of the effects of both drugs, but phenoxybenzamine enhanced the clonidine-induced increase of GFR. Neither haloperidol (1 mg/kg i.v.) nor bulbocapnine (3 mg/kg i.v.) interfered with the renal effects of clonidine. Clonidine s.c. caused hyperglycemia and glucosuria which did not account for the natriuresis. Clonidine thus appears to increase the GFR and "filtration fraction" (FF) by a phenoxybenzamine-insensitive rise of glomerular ultrafiltration, to depress ERPF by alpha-adrenergic afferent vasoconstriction, to induce natriuresis by a tubular action not blocked by phenoxybenzamine and to exert an antivasopressin effect, either by depressing pituitary vasopressin secretion or the renal response to vasopressin.

Animals↗
PubMed1984

Renal effects of nitrendipine monotherapy in essential hypertension.

Ten male patients with essential hypertension were studied on a constant diet (100 mEq of sodium daily) while on placebo, immediately following a 20-mg oral dose of nitrendipine, and during 1 week of nitrendipine therapy (10 mg twice daily). After 2 weeks of outpatient follow-up on 20-40 mg nitrendipine daily, the patients were readmitted and restudied with the same protocol. Glomerular filtration rate, effective renal blood flow, blood volume, and cardiac output were determined isotopically. Free water clearance and osmolar clearance following a water load were also measured. Twenty-four-hour urinary creatinine and electrolyte excretion were measured during the hospitalization periods. Blood pressure decreased significantly during the acute and chronic periods when compared to placebo. During the first 7 days of nitrendipine treatment, urinary sodium excretion increased significantly from control, and a mean deficit of 148 +/- 7 mEq (p less than 0.001) was calculated. There was a mean weight loss of 1.0 +/- 0.1 kg (p less than 0.05) after a week of treatment. Glomerular filtration rate, renal blood flow, blood volume, cardiac output, plasma renin activity, plasma catecholamines, and urinary aldosterone remained unchanged from control in both the acute and chronic periods. Compared to the placebo period, free water clearance (1.8 +/- 0.6 versus 2.9 +/- 0.5 ml/min; p less than 0.05) and osmolar clearance (1.9 +/- 0.3 versus 2.9 +/- 0.5 ml/min; p less than 0.05) increased significantly in the chronic period. The natriuresis and diuresis associated with nitrendipine therapy without any changes in renal function may represent a direct renal tubular effect of the drug.

Adult↗
PubMed1993

Case report: transcatheter renal embolization to effect renal ablation in recurrent PUJ obstruction in a patient with haemophilia.

We present a case of embolic ablation of a kidney with recurrent infected hydronephrosis in a patient for whom surgical resection was considered undesirable. The hydronephrosis recurred after embolization using gelfoam/steel coils but after a second embolization using lipiodol/absolute alcohol (50/50), the patient has remained asymptomatic. More than one embolization procedure may be necessary to effect renal ablation. Careful evaluation is necessary to determine whether ablation has been achieved. We recommend lipiodol/absolute alcohol as the embolic agent of choice.

Adult↗
PubMed1994

Evaluation of the single-injection plasma disappearance of technetium-99m mercaptoacetyltriglycine method for determination of effective renal plasma flow in dogs with normal or abnormal renal function.

Effective renal plasma flow (ERPF) was evaluated, using continuous-infusion p-aminohippurate clearance (CLPAH) and single-injection plasma clearance of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3; CLMAG3) methods. Simultaneous clearance determinations were made in 6 dogs: 2 determinations for each dog before, and 1 determination after renal failure was induced by administration of amphotericin B. Linear regression analysis was used to derive an equation to estimate ERPF from CLMAG3 after the single IV injection. A Student's t-test was used to compare pharmacokinetics between the dogs when they were healthy and when they were in renal failure. An F-test was used to determine the appropriate Student's t-test. Results indicated that CLMAG3 correlated reasonably well (r = 0.83, P < 0.0001) with ERPF obtained from the CLPAH value. The volume of distribution and elimination of 99mTc-MAG3 decreased during renal failure. Although there was minimal binding of 99mTc-MAG3 to erythrocytes, it was significantly (P = 0.0008) lower during renal failure. Protein binding was not significantly different during renal failure. All dogs had signs of nausea and emesis at variable times after injection of 99mTc-MAG3. Determination of CLMAG3 after a single injection provides an adequate means to rapidly assess ERPF in dogs. The technique could easily be performed in dogs with renal disease, thus providing valuable information regarding progression of naturally acquired renal failure.

Animals↗
PubMedDate not supplied

Renal effects of bumetanide.

Upon administration of bumetanide in normal human subjects, both glomerular filtration rate and effective renal plasma flow were increased, in approximately proportional amounts. Sodium excretion rose to 16 per cent of filtered load, whereas there was a chloriuresis of 23 per cent. During maximal water diuresis, the drug caused an increase in urine flow rate associated with a rise in osmolal clearance and no change in solute-free water clearance. Intravenous injection of the drug during hypertonic saline infusion into hydropenic subjects resulted in the virtual abolition of water abstraction from the collecting duct. The drug caused a modest increase in phosphate excretion but no change in the percentage of filtered bicarbonate excreted. Furthermore, neither urinary pH nor net hydrogen ion excretion was altered by the drug. The data suggest that bumetanide has its major action in the loop of Henle but that it also inhibits sodium transport in the proximal tubule. In addition, the nature of the proximal action does not appear to be related to a carbonic anhydrase inhibitory effect. These latter observations regarding the proximal action of the drug were verified by micropuncture studies performed in the dog.

Bicarbonates↗
PubMed1986

Blood levels and renal effects of atrial natriuretic peptide in normal man.

Since mammalian atria were recently found to contain vasoactive and natriuretic peptides, we investigated the following in normal humans: plasma human atrial natriuretic peptide concentrations, effective renal plasma flow (ERPF), glomerular filtration rate (GFR), urinary water and electrolyte excretion, blood pressure (BP), and catecholamine, antidiuretic hormone (ADH), angiotensin II, and aldosterone levels before, during, and after intravenous administration of the newly synthetized alpha-human atrial natriuretic peptide (alpha hANP). In 10 subjects alpha hANP given as an initial bolus of 50 micrograms followed by a 45-min maintenance infusion at 6.25 micrograms/min increased plasma alpha hANP from 58 +/- 12 to 625 +/- 87 (mean +/- SEM) pg/ml; caused an acute fall in diastolic BP (-12%, P less than 0.001) and a hemoconcentration (hematocrit +7%, P less than 0.01) not fully explained by a negative body fluid balance; increased GFR (+15%, P less than 0.05) despite unchanged or decreased ERPF (filtration fraction +37%, P less than 0.001); augmented (P less than 0.05- less than 0.001) urinary chloride (+317%), sodium (+224%), calcium (+158%), magnesium (+110%), phosphate excretion (+88%), and free water clearance (from -0.76 to +2.23 ml/min, P less than 0.001) with only little change in potassium excretion; and increased plasma norepinephrine (P less than 0.001) while plasma and urinary epinephrine and dopamine, and plasma ADH, angiotensin II, and aldosterone levels were unchanged. The magnitude and pattern of electrolyte and water excretion during alpha hANP infusion could not be accounted for by increased GFR alone. Therefore, in normal man, endogenous alpha hANP seems to circulate in blood. alpha hANP can cause a BP reduction and hemoconcentration which occur, at least in part, independently of diuresis and are accompanied by sympathetic activation. An increase in GFR that occurs in the presence of unchanged or even decreased total renal blood flow is an important but not sole mechanism of natriuresis and diuresis induced by alpha hANP in man.

Atrial Natriuretic Factor↗
PubMed1994

Chlorotyrosine exerts renal effects and antagonizes renal and gastric responses to atrial natriuretic peptide.

3-Chloro-L-tyrosine (3CT) is an inhibitor of tyrosine hydroxylase, the rate-limiting enzyme for catecholamine synthesis. In vivo inhibition of tyrosine hydroxylase results in lower catecholamine levels. 3CT (0.5 mg/kg), administered as a bolus i.v. to anesthetized uninephrectomized rats, elicited increases of 72% and 44% in urinary sodium concentration and volume, respectively, whereas a dose of 1 mg/kg caused increases of 27% and 29%. 3CT, 1 mg/kg, resulted in a 2-fold increase in plasma aldosterone (ALD); 0.5 mg/kg was without significant effect. At a dose of 1 mg/kg 3CT significantly antagonized the renal effects of atrial natriuretic peptide (ANP) (1.5 micrograms kg-1 min-1 by intrarenal infusion), expressed as an enhanced excretion of urine volume (102 +/- 14 vs. 70 +/- 11 microliters/min) and sodium (16.1 +/- 1.8 vs. 11.5 +/- 1.7 microEq/min) and increased osmolar clearance (171 +/- 12 vs. 144 +/- 13 microliters/min). A dose of 0.5 mg/kg of 3CT did not produce these same responses to ANP. The increased urine flow caused by 3CT may reflect reduced norepinephrine synthesis. The inverse dose-effect relationship of 3CT on urine flow rate may result from concomitant depletion of dopamine (DA) and elevated circulating ALD. The antagonism of 3CT on responses to ANP is not at the receptor level, because 3CT did not compete for [125I] ANP binding or inhibit ANP-stimulated guanylate cyclase in kidney cell membranes. It was proposed that the reduced basal sympathetic and renal DA tone, together with the elevated ALD level, account for this antagonism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Quantitative renal scintigraphic determination of effective renal plasma flow in dogs with normal and abnormal renal function, using 99mTc-mercaptoacetyltriglycine.

Effective renal plasma flow (ERPF) was evaluated, using the measurement of p-aminohippurate clearance (CLPAH) and quantitative renal scintigraphy (QRS) with 99mTc-mercaptoacetyltriglycine (99mTc-MAG3). The CLPAH and QRS determinations were made in 6 dogs: 2 determinations for each dog before, and 1 determination after induction of renal failure by administration of amphotericin B. Least-squares regression analysis was used to derive an equation to estimate ERPF from QRS data. The results indicated that QRS, using 99mTc-MAG3, correlated reasonably well (r = 0.82, P < 0.001) with ERPF determined from the CLPAH value. The right kidney contributed 53.3% of global ERPF (P = 0.002). Hepatobiliary excretion of 99mTc-MAG3 was variable within each dog. There was not a consistent pattern with respect to time or renal function. All dogs had nausea or emesis, or both, after IV administration of 99mTc-MAG3. The QRS method with 99mTc-MAG3 provides an adequate means to estimate ERPF in healthy dogs and dogs with renal failure.

Animals↗
PubMed1999

Tc-99m MAG3 renal studies: renogram and effective renal plasma flow in spinal cord injury patients.

To determine whether years since injury, level of injury, degree of injury, gender, or age influence renal function in 66 spinal cord injuries (SCI) patients without urological complications, individual kidney effective renal plasma flow (ERPF) and radionuclide renogram (RR) were measured using technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3). The 176 individual kidneys included 84 kidneys with normal ERPF and RR, 48 kidneys with normal ERPF but abnormal RR, and 44 kidneys with abnormal ERPF and RR. The incidence of abnormal Tc-99m renal study results was higher in the kidneys of female patients (37/54, 68%) than of male patients (55/122, 45%) (p < 0.05). We found that Tc-99m MAG3 renal studies including ERPF and RR are safe and noninvasive urological screening tests for SCI patients.

Adult↗