Dynamics of renal excretory function after furosemide or ethacrynic acid administration to unanaesthetized dogs after mannitol infusion or chronic renal denervation.

To unanesthetized dogs with exteriorized ureter allowing separate collection of urine from both kidneys, furosemide 0.2 mg/kg b.w. or ethacrynic acid 0.22 mg/kg b.w. was given intravenously. The volume of collected urine and the excretion of sodium, chloride, potassium and calcium were studied. The dynamics of diuretic administration was programmed. After unilateral renal denervation furosemide or ethacrynic acid was given and the response of the denervated (left) and intact (right) kidneys was compared. Prior to renal denervation the same dogs were infused with a 15% mannitol solution in a quantity and at a rate causing an increase of diuresis approximately equal to that after renal denervation. The effect of furosemide given with and without mannitol infusion was compared. Description of the dynamics of renal excretory function used by us allowed to demonstrate the modulating role of renal nerves in the regulation of water, chloride and sodium excretion after the administration of diuretics. The principal part of the compensatory reabsorption of chloride after renal denervation occurred in the ascending limb of Henle's loop. Comparison of calcium excretion after renal denervation and administration of furosemide with that after mannitol and furosemide allows to assume that after renal denervation calcium load from the proximal to the distal tubules does not increase.