Renal function in sheep during infusion of alkali metal ions into the renal artery.

Abstract

SUMMARY1. The effect on renal function of 1 M solutions of LiCl, NaCi, KC1, RbCl and CsCl and 3 M-NaCl infused close-arterially to the kidney for 10 min at 0*7 ml./min has been studied in nine experiments on four unilaterally nephrectomized sheep. The levels of flow, electrolyte concentration and electrolyte excretion in the urine were measured before, during and for 50 min after the infusions.2. The infusion of 1 M-NaCl produced little change in urine flow and composition whereas 3 m-NaCl resulted in relatively small increases in urine flow and sodium excretion.3. The infusion of lithium, potassium, rubidium and caesium resulted in marked increases in urine flow, urinary sodium concentration and excretion, urinary potassium excretion and osmolal clearance while the urinary potassium concentration decreased.4. Changes in urine flow and urinary pH during the infusions of all the alkali ions except sodium were consistent with increased urinary bicarbonate excretion.5. The osmolal clearance was increased by the infusion of lithium, potassium, rubidium and caesium, but equivalent increases in the rate of solutefree water reabsorption did not occur.6. The infusion of caesium resulted in a depression of the glomerular filtration rate (G.F.R.) which was not observed when the other alkali ions were infused.7. The effects of lithium, potassium and rubidium on urine flow and composition were rapid in onset and the residual effects of these ions, on cessation of infusion, were relatively short. The effects of caesium were slow in onset and prolonged in duration.8. It was concluded that lithium, potassium, rubidium and caesium altered urine flow and electrolyte excretion by acting upon common mechanisms which were predominantly intra-renal and located in the proximal segment of the nephron.

Effect of intraventricular injection of transmitter substances and temperature on autonomic functions of conscious sheep.

“…The mean ratio of the increase in solute-free water reabsorption to the increase in osmolal clearance at maximum urine flow after carbachol injection was 0d15 which can be interpreted as indicating that the increase in water and electrolyte excretion at the time resulted from reduction in the proportion of the glomerular filtrate being reabsorbed in the proximal tubule (Beal & Harrison, 1975). The fall in urine flow during the second 60 min of the observation period accompanied by a rise in solute-free water reabsorption may indicate some increase in vasopressin activity at this time.…”

The Effect of Plasma Potassium in Determining Normal Rates of Excretion of Potassium in Dogs

“…There is no consistent change in any plasma constituent except plasma K. There seems therefore no explanation other than that the changes in the urine are due to the increase in plasma K acting directly on the kidneys. Injection of K into the renal artery has been shown to cause increase in K excretion, with a small increase in Na excretion [Beal and Harrison, 1975;Harrison et al, 1970]. Several authors [Anderson and Pickering, 1962;Scott, 1969;Mason and Scott, 1972;Beal et at., 1973] have described immediate increase in K excretion and increased Na excretion on intravenous injection of K salts in larger doses than those used here.…”

The Effect of High Rates of Vasopressin Administration on Renal Potassium and Sodium Excretion During Potassium Loading in the Sheep

“…Micropuncture studies in rat and dog have shown that during potassium loading, the reabsorption of sodium and water in the proximal tubule is depressed thus providing an explanation for the natriuretic diuresis observed in hyperkalaemia (Malnic, Klose & Giebisch, 1966;Watson, 1966;Brandis, Keyes & Windhager, 1970). Observations in potassium-infused sheep although less direct, suggest that the same explanation is tenable for the increase in urinary sodium excretion in this species also (Beal, BudtzOlsen, Clark, Cross & French, 1973;Beal & Harrison, 1975).…”

“…As Beal & Harrison (1975) have observed the concentration of solutes in the urine collected from a bladder catheter does not alter as soon as the urine flow alters because there is a finite volume or 'deadspace' between the kidney and the exterior in the ADH ON RENAL ELECTROLYTES DURING POTASSIUM LOADING urinary tract and catheter. This 'dead-space' volume tends to cause errors in the measurement of rates of urinary excretion of solutes particularly when the urine collection times are short and the flow rate is changing rapidly.…”

“…As Beal & Harrison (1975) urinary tract and catheter. This 'dead-space' volume tends to cause errors in the measurement of rates of urinary excretion of solutes particularly when the urine collection times are short and the flow rate is changing rapidly.…”