[Effects of propranolol and atenolol on the rat kidney]

The present experiments were designed to study the renal effects of propranolol and atenolol in rats. Wistar rats were anesthetized with urethane and continuously hydrated with saline solution. In one group of the rats, the drugs were injected into the jugular vein. In the other group of the rats, the drugs were injected into the abdominal aorta through a canula which was inserted from the left carotid artery into the aorta up to the middle between forking points of left and right renal arteries. Intravenous infusion of propranolol and atenolol increased urine volume (UV), urinary sodium excretion, urinary potassium excretion and urinary chloride excretion. Propranolol and atenolol, which were intraaortally injected, produced an increase in UV and sodium concentration in the urine, inducing a more marked increase in total sodium amount excreted from both kidneys by propranolol than by atenolol. However, the natriuretic response was far more marked in the left kidney than in the right kidney in the case of atenolol administration as compared to that in the case of propranolol. It was speculated, therefore, that the natriuresis induced by these drugs was the first pass effect on the rat kidneys. It was also noted that the first pass effect of atenolol on kidneys was more marked than that of propranolol.