Abstract
Summary
The effects of bethanechol chloride (5 and 10 mg/kg) and arecoline hydrochloride (2 mg/kg) on the concentration gradients of sodium and potassium were determined in renal papilla, medulla, and cortex of rats sacrificed at the height of the saluresis produced by the subcutaneous injection of these agents. Bethanechol produced an increased urinary excretion of sodium and potassium and an increased osmolality of the urine with no change in volume. Arecoline had been reported previously to have similar effects in rats. The concentration gradients of sodium and potassium in the kidneys of the rats treated with bethanechol or arecoline were not decreased compared to control rat kidneys.
In the chicken, bethanechol chloride (10 and 20 μg/kg/min) infused into the saphenous vein produced a unilateral increase in urinary volume and an increase in excretion of sodium, potassium, and chloride. Similar effects were noted in the dog when bethanechol was given into one renal artery. These effects were inhibited by atropine.
Since the chicken kidney concentrates urine very little, and since there was no decrease in concentration gradients in kidneys of rats at the height of the saluresis, it is concluded that bethanechol exerts its diuretic or saluretic effects in these species primarily by a direct inhibitory effect on tubular reabsorption of sodium.
The competent technical assistance of Mrs. Betty Maddux is gratefully acknowledged.
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