Lack of effect of antioxidant therapy during renal ischemia and reperfusion in dogs.

Acute ischemic renal failure is of great clinical importance because of its frequent occurrence and the high mortality it causes. Recent observations indicate that reperfusion has its own dangers because of oxygen-derived free radicals. To study this problem, ischemia was evoked in dogs in one kidney, by clamping the left renal artery for 45 min.

Study of the effect of superoxide dismutase on acute renal failure in dogs.

Warm ischaemia was provoked by occlusion of the left renal artery in dogs narcotized with Nembutal and it was studied whether a small (0.5 mg/kg body weight /n = 6/) or a large dose (5 mg/kg body weight /n = 7/) of superoxide dismutase (SOD) improves renal function during 90 min reperfusion, compared to the control group (n = 6). In the first period after release of occlusion (min 0-15) the GFR and cPAH values reached 10-20% of those in the contra lateral kidney with normal circulation.

Effect of ventilation on sodium excretion in the anesthetized dog with unilateral renal denervation.

We studied if the effect of mechanical ventilation induced to keep arterial blood gas values within normal physiological limits has any influence on renal sodium excretion in anesthetized dogs (n = 17) subjected to acute unilateral renal denervation. Compared to the control and the postcontrol periods, ventilation elevated arterial pO2 from 86 +/- 5 to 96 +/- 5 mmHg and blood pH from 7.37 +/- 0.

Effect of free radicals in ischaemic renal failure in the dog.

After a 30-minute control period ischaemia was evoked in dogs under Nembutal (30 mg/kg, i.v.) anesthesia, by clamping the left renal artery for 45 minutes.

No effect of isolation on blood pressure and daily electrolyte excretion in rats.

The effects of isolation stress on mean blood pressure (BP) and on body weight, water and food intake as well as on urine flow, urinary sodium and potassium excretion were studied in CFY and Long Evans rats. During a 7 day isolation period, food and water intake as well as urine flow, urinary sodium and potassium excretion, as expressed for 100 g body weight, were not changed in either group. Body weight increased similarly in isolated (38 +/- 2 g) and aggregated (41 +/- 5 g) CFY rats.

Renal nerves in exaggerated water and sodium excretion by hypertrophied kidney of anesthetized rats.

The effect of acute renal denervation (RD) on water (V), sodium (UNaV), and potassium excretion (UKV) from the hypertrophied and control kidney was studied in 5-sec-butyl-5-ethyl-2-thiobarbituric acid (Inactin)-anesthetized male rats 7 days after unilateral nephrectomy (Nx) or sham operation (SNx). V, UNaV, and UKV from the hypertrophied kidney were similar before and after RD or sham RD. In contrast, in SNx rats, left RD resulted in an ipsilateral increase in V (from 2.

Renal nerves and sodium conservation in conscious rats of different strains kept on various diets.

Earlier contradictory results as to whether renal nerves are necessary for adaptation to a low dietary sodium intake in the rat were ascribed to strain differences or to sympathetic stimulation caused by carbohydrates when changing from a low-sucrose normal-sodium diet to a high-sucrose sodium-deficient diet. In the present work, daily sodium excretion was studied for 4 days before and after bilateral renal denervation or sham operation in three strains of rats (CFY, Wistar, and Long Evans). After ingesting a normal sodium diet containing no sucrose, CFY and Wistar rats were fed a sodium-deficient diet containing 67% sucrose.

Supersensitivity of the renal tubule to catecholamines in the chronically denervated canine kidney.

Experiments were performed on anesthetized dogs to study whether or not renal tubules of the chronically denervated kidney show supersensitivity toward circulating catecholamines. In one kidney the influence of plasma catecholamines was inhibited by intrarenal administration of the alpha adrenergic receptor blocker phenoxybenzamine (POB, 2 micrograms/min), and renal parameters of the infused kidney were compared to those of the contralateral noninfused organ. Before POB infusion urine flow (V), urinary sodium and potassium excretion (UNa V, UKV) as well as clearance of inulin and PAH (GFR, CPAH) were similar in infused and contralateral kidneys in all groups studied.

Fasting induces denervation natriuresis in the conscious rat.

The participation of renal nerves in the regulation of sodium excretion was studied in fed and overnight-fasted rats subjected to acute or chronic left kidney denervation or sham operation. Clearance experiments were performed on conscious restrained animals. Urine flow, glomerular filtration rate (GFR), and urinary sodium excretion were not different in left and right kidneys of sham-operated rats.

Water and electrolyte transport in Henle's loop and distal tubule after renal sympathectomy in the rat.

The effect of acute renal denervation (AD) on transtubular movement of water and electrolytes in Henle's loop (LH) and distal tubule (DT) of superficial nephrons was studied by the technique of in vivo microperfusion in Inactin-anesthetized hydropenic male rats. In time-control experiments (n = 6) no changes in either whole kidney or single nephron function were detected. Predenervation results of denervation experiments (n = 10) were similar to those of the time-control series.

Proximal tubular transport and urinary excretion of sodium after renal denervation in sodium depleted rats.

The effect of unilateral renal denervation on renal handling of water, sodium and potassium was studied with clearance and micropuncture techniques in sodium depleted anaesthetized rats in the nondiuretic state. In clearance experiments renal denervation resulted in a +140 and +320% increase in urine flow and potassium excretion, but sodium excretion of innervated (I) and denervated (D) kidneys was similar (I: 12.0 +/- 2.

Time course of denervation diuresis and natriuresis in the anaesthetized rat.

The effect of unilateral renal sympathectomy on renal excretion of water and sodium was studied in three groups of Inactin-anaesthetized rats: 1-3, 4-19, and 20-35 weeks after denervation. Increased sodium excretion from the denervated kidney in the absence of changes in GFR was observed up to 35 weeks following renal denervation. Thus, in a functional sense, renal reinnervation may have only been partial during the time interval studied.

Intratubular and peritubular capillary hydrostatic and oncotic pressures after chronic renal sympathectomy in the anaesthetized rat.

The possible role of peritubular capillary physical forces in the diuretic-natriuretic effects of chronic renal denervation was investigated in Inactin-anaesthetized nondiuretic control (C) and unilaterally denervated (D) rats. Micropuncture techniques were combined with measurement of intratubular and peritubular capillary hydrostatic pressures and afferent and efferent arteriolar plasma oncotic pressures were determined, as well. Compared to data of C rats and of innervated kidneys, marked denervation diuresis and natriuresis were seen without changes in GFR.

Renal excretion of sodium after bilateral renal sympathectomy in the anaesthetized and conscious rat.

1. The effect of bilateral renal denervation on sodium excretion was studied in conscious rats on normal, low and high sodium diet, and in rats recovering from anaesthesia, as well as in anaesthetized rats fed a normal sodium diet. 2.

Water and sodium excretion in unilaterally denervated normal and sodium depleted anesthetized rats before and after plasma volume repletion.

The possible role of a reduction in plasma volume (PV) by surgery as well as the importance of dietary Na supply in denervation natriuresis have been investigated on Inactin-anesthetized male rats subjected to acute unilateral renal sympathectomy. Four groups were studied: I. Normal Na diet (n = 14); II.

Tubular transport and urinary excretion of phosphate after renal denervation in the anesthetized rat.

Tubular transport of phosphate (Pi) was studied using clearance and tracer microinjection techniques in Inactin-anesthetized male rats subjected to left kidney denervation. Experiments were conducted in the following groups: i) acute denervation (AD); ii) chronic denervation (CD); iii) acute denervation plus thyroparathyroidectomy (AD + TPTX); iv) microinjection with AD. Besides a marked diuresis and natriuresis with no difference in GFR between innervated (inn) and denervated (den) kidneys, unilateral renal denervation resulted in an increased urinary excretion and decreased tubular reabsorption of inorganic phosphate.

Aldosterone binding along the rabbit nephron: an autoradiographic study on isolated tubules.

The sites of action of aldosterone (A) along the tubule of rabbit kidney were studied by autoradiographic localization of mineralocorticoid-binding sites on microdissected tubular segments. Kidney pyramids were incubated at 30 degrees C for 1 h in a collagenase solution with [3H]aldosterone at a concentration of 1.5 X 10(-9) M with and without an excess unlabeled A.

Effect of renal denervation on free flow proximal tubular potential difference in the rat.

Proximal transtubular potential difference (PD) was measured using the semi-microelectrode technique in control (C, n = 10) and unilaterally denervated (D, n = 10) rats. Acute renal sympathectomy resulted in a twofold and fourfold increase in diuresis and sodium excretion, respectively, with no change in GFR. PD (mean +/- S.

Effect of a "minimal natriuretic and diuretic" dose of prostaglandin E1 (PGE1) on the intratubular and peritubular pressures in anaesthetized rats.

A "minimal natriuretic and diuretic" dose (3.4--4.2 ng/min/kg) of prostaglandin E1 (PGE1) as previously estimated was infused into the aorta in anaesthetized rats.

[Neural regulation of substance transport in the kidney].

The denervation diuresis and natri uresiswere manifest in anesthetized dog and rats after acute or chronic renal sympathectomy with no changes in RBF, GFR or in their intrarenal distribution. Micropuncture showed the principal site of action of renal denervation on to be within the proximal tubule. The unchanged relationship between reabsorbed sodium and consumed oxygen suggested that active transport of Na decreased on denervation.

Effect of splanchnicotomy on the renal excretion of d-glucose in the anaesthetized dog.

The effects of acute intravenous d-glucose (G) loading were studied on anaesthetized, unilaterally splanchnicotomized ("renal denervation") dogs. Glomerular filtration rate (GFR) was generally not different on the innervated and denervated side, while urine flow (V), sodium excretion (UNaV) and urinary excretion (UGV) of glucose on the splanchnicotomized side were significantly increased at any plasma G concentration. Tubular reabsorption (TG) as well as Tm of G in denervated kidneys was considerably depressed.

Effect of splanchnicotomy on the renal excretion of uric acid in anaesthetized dogs.

The renal excretion of uric acid was examined during acute i.v. urate (Ua) loading on unilaterally splanchnicotomized ("renal denervation") anaesthetized mongrel dogs.

Effect of splanchnicotomy on the renal excretion of para-aminohippuric acid in the anaesthetized dog.

Renal excretion of para-aminohippuric acid (PAH) was studied during PAH loading on unilaterally splanchnicotomized ("denervated") anaesthetized dogs. Urine flow, sodium excretion of denervated kidneys were significantly increased. Below a plasma concentration of 20 mg% there were no differences between intact and denervated kidneys in urinary excretion and in calculated tubular transport of PAH.