Abstract
In the albino rat, the s.c. injection of the beta-adrenergic agonist, isoproterenol, invariably elicited copious drinking which was not accompanied by an anticipated increase in urine volume. Prior water loading did not abolish this drinking and uncovered marked simultaneous inhibition of the urinary flow. In contrast, rats injected with the alpha-adrenergic stimulant, metaraminol, exhibited an increased urinary flow in the absence of conspicuous attempts by the animals to recoup the water loss by drinking. Pretreatment with the beta-adrenergic antagonist, propranolol, blocked the isoproterenol-induced drinking and inhibition of urine flow, whereas alpha-adrenergic blockade with tolazoline elicited isoproterenol-like effects due to beta-adrenergic preponderance. A clear-cut dose-response relationship was demonstrated to exist for the effects of both isoproterenol and propranolol. The incisive effects upon the thirst drive elicited by the peripheral administration of adrenergic agonists and antagonists are considered evidence for central nervous system involvement. Specifically, these findings and the concomitant occurrence of reciprocal inhibition or increase in urinary flow are believed to be consistent with the concept of direct or reflex activation of central mechanisms of body water regulation.
Footnotes
- Received October 10, 1966.
- Accepted June 15, 1967.
- © 1967 by The Williams & Wilkins Company
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