Effects of catecholamines and adrenergic blockade on fluid reabsorption in isolated rat cauda epidiymidis

The rate of fluid reabsorption in the cauda epididymidis of rat has been measured in vitro. Both adrenaline 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 consisted of two components. In the presence of an alpha blocker, noradrenaline caused an increase, while in the presence of a beta blocker, it produced an inhibition in the rate of fluid reabsorption. The effects of these adrenergic agents were only observed when sodium ions 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 sodium in terms of the presence of alpha and beta receptors in the epithelium of the rat cauda epididymidis.