EFFECTS OF CATECHOLAMINES AND ADRENERGIC BLOCKADE ON FLUID REABSORPTION IN ISOLATED RAT CAUDA EPIDIDYMIDIS

Abstract

The rate of fluid reabsorption in the cauda epididymidis of rat was measured in vitro. Both adrenaline [epinephrine] and isoprenaline produced a prompt reversible and dose dependent increase in the reabsorption rate. These effects were completely blocked by propranolol. The response to noradrenaline [norepinephrine] consisted of 2 components. In the presence of an .alpha. blocker [phenoxybenzamine], noradrenaline caused an increase, while in the presence of a .beta. blocker [propranolol], it produced an inhibition in the rate of fluid reabsorption. The effects of these adrenergic agents were only observed when Na+ were present in the intraluminal fluid, suggesting that they only affect the Na+-dependent component of fluid reabsorption. The possibility that they may affect the active transport of Na in the duct was discussed. The effects of these adrenergic agents were interpreted in terms of the presence of .alpha. and .beta. receptors in the epithelium of the rat cauda epididymidis.