Abstract
In an attempt to delineate the role of beta-adrenoceptors found to be existing in the brain tissue in the central regulation of renal function, isoproterenol, a ${\beta}-adrenergic$ agonist, was administered directly into a lateral ventricle of the rabbit brain and the changes of renal function were observed. Also, the effects of propranolol, a specific ${\beta}-adrenergic$ blocking agent, and its influence upon the isoproterenol action were studied. Isoproterenol, in doses ranging from 5 to $50\;{\mu}g/kg\;i.c.v.$, elicited antidiuresis which seemed to be related to the decreased renal hemodynamics brought about by the systemic hypotension. With moderate doaes of $15\;{\mu}g/kg$ the antidiuresis was less prominent and there was a tendency toward natriuresis, but with higher doses the natriuretic effect became less evident, overrun by the systemic hypotension. Propranolol, $500\;{\mu}g/kg\;i.c.v.$, produced little effect on the renal function, but it eliminated the antidiuretic action of $50\;{\mu}g/kg$ isoproterenol i.c.v. and reversed it to a diuretic and natriuretic one, along with increases in renal plasma flow and glomerular filtration rate. The systemic hypotension also was markedly attenuated by propranolol pretreatment. Thus, it was evident that the renal action of i.c.v. isoproterenol was not blocked by propranolol and became explicit only when the hypotensive action of isoproterenol which seems to he propranolol-sensitive is removed. Various possibilities to account for this disparity in sensitivity were discussed. It is suggested from these observations that the central ${\beta}-adrenoceptors$ might also be involved in the regulation of renal function along with ${\alpha}-adrenoceptors$, though less significant than the latter.
중추의 ${\beta}-adrenoceptor$가 신장기능의 조절에 있어서 어떠한 역할을 하고 있는지를 알고자, 가토의 측뇌실내에 isoproterenol 및 propranolol을 투여하여 신장기능의 변동을 관찰하였다. Isoproterenol은 $5{\sim}50{\mu}g/kg$ i.c.v.의 범위에서 항이뇨작용을 나타냈으나 이는 주로 전신혈압하강에 따르는 신혈류 및 사구체여과율의 감소에 기인하며 세뇨관에서의 Na 재흡수억제효과는 음폐된 것으로 추론되었다. Propranolol $(500\;{\mu}g/kg\;i.c.v.)$은 신장기능에 현저한 변동을 초래하지 아니하였으나, propranolol후에 isoproterenol을 투여하면 전신혈압하강은 현저히 약화됨과 동시에, Na, K 배설의 증가와 신혈류의 증가, 그리고 뇨량증가경향이 관찰되었다. 즉, prapranolol에 의하여 isoproterenol의 강압작용은 영향을 받으나 신장작용은 영향받지 아니하고 현저하게 표현되었다. 본연구의 결과는, 중추의 ${\beta}-adrenoceptor$도 ${\alpha}-receptor$보다는 약하지만 신장기능의 조절에 있어서 어떤 역할을 하고 있음을 시사하였다.