EFFECT OF BETA-ADRENERGIC STIMULATION OF THE SEPTAL AREA ON RENAL EXCRETION OF ELECTROLYTES AND WATER IN THE RAT

In order to evaluate the relative roles played by the central beta-receptors in the regulation of renal excretion of Na+, K+ and urine volume a study was carried out on the effect of intraseptal injections of isoproterenol on untreated rats and on rats pretreated with locally injected butoxamine and practolol. Injection of 20-160 nmol isoproterenol into the median septal area elicited a dose dependent decrease in Na+, K+ and urinary volume. Intraseptal injection of 40 nmol isoproterenol elicited a significant decrease in Na+ urinary excretion and in urinary volume during the 2 hr period immediately following injection. This effect was blocked by 160 nmol of locally injected butoxamine administered before isoproterenol. In contrast, pretreatment with practolol (160 nmol) did not alter the effect induced by isoproterenol. Pretreatment with these beta1 and beta2 antagonists did not abolish the effect of isoproterenol on K+ urinary excretion. The beta2 agonist agents, terbutaline and salbutamol, elicited a significant decrease in renal excretion of water and of the two salts. These results indicate that activation of beta2 receptors in the septal area elicits a decrease in Na+ and urinary volume excretion, while the same effect on K+ cannot be described as being due to type 2 beta-receptors. © 1979.