Effect of strophanthidin on the renal tubules of dogs

Abstract

The nature and mechanism of the diuresis produced in the dog by strophanthidin was investigated by infusion of the drug into one renal artery. Saline-loaded dogs respond to strophanthidin infusion with a prompt fall in glomerular filtration rate (GFR) and a delayed saluresis and diuresis. The effect on electrolyte transport can be blocked by loading with potassium salts but the fall in GFR can be only partially prevented. Strophanthidin given to adrenalectomized dogs produces the same effect as in the intact animal. The ability to maintain a steep transtubular hydrogen ion concentration gradient is severely impaired. The data are best interpreted as inhibition of the potassium arm of a linked Na-K exchange across the peritubular cell membrane, with diuresis occurring secondary to this block. Impairment of the ability to maintain a steep hydrogen ion concentration gradient indicates an additional effect on linked exchange occurring at the luminal surface of the cell.