The effects of ketamine and innovar on the renal cortical and medullary blood flow of the dog

To study the effects of Ketamine and Innovar on renal function, the renal cortical and medullary blood flows of dog were measured using a thermo-electrical flowmeter, along with the urine output, blood pressure and pulse rate. Ketamine decreased the renal cortical blood flow and the urine output. Innovar increased the renal cortical blood flow, but did not alter the medullary blood flow appreciably, and decreased the urine output. Neither of these variations in renal blood flows ran parallel with variations in the arterial pressure nor did variations in the urine output run parallel with those in the blood flows. All anaesthetic agents are inhibitory to kidney, but Innovar may be preferred to other anaesthetics in view of the finding that the renal blood flows are well maintained even under anaesthesia with this agent.

Effects of diuretic states on collecting duct fluid flow resistance in the hamster kidney

Hydrostatic pressures were measured in cortical tubules, long loops of Henle, terminal collecting ducts, and in vasa recta in hamsters. In hydropenia, the loops of Henle and terminal collecting ducts provided the major fluid flow resistances, as judged by the location of hydrostatic pressure drops. In mannitol or saline diuresis, hydrostatic pressures in all tubular segments increased, but pressure drops in loops of Henle disappeared, indicating dilatation of loops. The major pressure drop was in terminal collecting ducts, especially in ducts of Bellini, even though these tubular segments also dilated. At highest urine flows, cortical tubule pressures were higher with the ureter and renal pelvis intact than when they were excised, suggesting laminar flow in the ureter adds a flow resistance at high flows. The pressure drop across the medullary capillary bed was 1-2 mmHg. The summation of medullary capillary hydrostatic and colloid osmotic pressures favored fluid uptake from the interstitium, a relationship enhanced by vasa recta geometry which ensures that descending vasa recta offer 4 times the flow resistance of ascending vessels.

Intrarenal distribution of blood flow and renin in chronic congestive heart failure

Intrarenal distribution of blood flow was measured by the 133xenon washout curve in 33 patients with heart disease. Plasma renin activity and sodium concentration were also measured on the day when the xenon study was performed. The patients were divided into three groups according to cardiac index: Group I whose cardiac index showed higher than 3.50 1/min/M2, BSA, group II whose index ranged from 2.50 to 3.50, and group III who had lower than 2.50. Total renal blood flow was significantly decreased in group II (p less than 0.001), as compared with normal controls. The percents of the total renal blood flow supplied to component I decreased significantly in group I, II (p less than 0.05) and group III (p less than 0.01). The flow rate in component I decreased significantly only in group II (p less than 0.05) and group III (p less than 0.01). There was a significant increase in the percent distribution of component II in group II (p less than 0.05) and in group III (p less than 0.01). The flow rate of component II showed a slight increase in group I and III. The study of autoradiographs done in dogs with heart failure demonstrated that component I corresponded to a cortical area having a relatively faster flow rate, whereas component II corresponded to the cortical area which was perfused more slowly. Accordingly, component III indicated outer medulla. There was no apparent relation between intrarenal distribution of blood flow and plasma renin activity although the latter tended to be elevated in patients treated with diuretics. In view of the data available it was concluded that outer cortical as well as outer medullary blood flow are decreased in chronic congestive heart failure and that there is no apparent correlation between outer cortical flow and plasma renin activity.

Experimental papillary necrosis of the kidney. IV. Medullary plasma flow

To test the thesis that vasoconstriction plays a significant role in the pathogenesis of papillary necrosis caused by bromoethylamine hydrobromide (BEA), medullary plasma flow was determined in rats treated with BEA. Medullary blood flow was normal (1/2) to 1 hour after BEA treatment, and was actually elevated 6 hours after BEA. There was no increase in plasma levels of prostaglandins A and E, which would have been expected if there had been medullary ischemia. Pretreatment with reserpine, which inhibited the development of papillary necrosis, had little effect on medullary plasma flow. These observations do not support the notion that vasoconstriction is the mechanism by which BEA causes papillary necrosis.

The effect of vasopressin upon the vasculature of the isolated perfused rat kidney

The timed uptake of (131)I-labelled human serum albumin was used as an index of regional perfusion in the isolated rat kidney.1. Arginine vasopressin in doses of 1, 5 and 10 muu./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the 5 muu. dose.2. Ornithine-8-vasopressin in doses of 5 and 10 muu./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the 10 muu. dose.3. When the relative viscosity of the perfusate was increased to a value of 2.0 from the control value of 1.7, both papillary perfusion and total renal perfusion were reduced.4. Arginine vasopressin further reduced papillary flow in kidneys perfused with high viscosity artificial plasma.

Vasopressin-induced increase in renal lymph flow and natriuresis in dogs

1. Renal lymph flow and composition as well as renal haemodynamics and electrolyte excretion were studied in dogs during three experimental periods: control [endogenous antidiuretic hormone (ADH)], water diuresis (low ADH) and during exogenous ADH administration.

2. During water diuresis CPAH and CCr were significantly increased although lymph flow and urinary sodium excretion were unchanged.

3. Infusion of ADH significantly increased renal lymph flow and sodium excretion. However, when compared with values obtained during water diuresis, ADH infusion did not significantly change clearance for p-aminohippurate (CPAH), creatinine (Ccr) and osmolal clearance (Cosm), filtration fraction or net capillary colloid osmotic pressure in dogs forming concentrated urine.

4. It is suggested that a shift of blood flow from vasa recta to outer medullary capillaries, with increased capillary protein leakage and medullary interstitial volume, is responsible for the changes observed in lymph flow and sodium excretion.

Renal prostaglandins: determinants of intrarenal distribution of blood flow in the dog

1. Indomethacin inhibited the synthesis of prostaglandins in isolated blood-perfused canine kidneys.

2. Blood flow to the inner cortex was reduced to a greater degree by indomethacin than blood flow to the outer cortex, resulting in redistribution of fractional blood flow to the outer cortex.

3. A prostaglandin, probably PGE2, appears to participate in the regulation intra-renally of medullary vascular resistance and thereby inner cortical blood flow.

Vascular permeability of the renal medullary vessels in the mouse and rat

The vascular permeability of the vessels of the renal medulla of normal rats and mice and potassium-deficient rats was studied by using ferritin, horseradish peroxidase and carbon particles as markers. Fenestrated endothelia are more permeable to ferritin and horseradish peroxidase than nonfenestrated endothelia. The ease with which the tracers are able to pass from the vascular lumina through the endothelia into the interstitium is directly related to the size of the tracers (horseradish peroxidase permeates most readily, followed by ferritin and carbon particles, in this order), suggesting the presence of a molecular sieving mechanism for the passage of substances through the capillary walls of the renal medulla. At the initial stage after injection of horseradish peroxidase and ferritin, these tracers pass from the medullary vascular lumina into the interstitium, not from the tubular lumina into the interstitium. It appears that the passage of ferritin and horseradish peroxidase through the vascular wall is enhanced in potassium-deficient rats.