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측뇌실내 Calcium Channel Agonist Blocker 신장기능에 미치는 영향 |
김경근 |
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Abstract |
In order to elucidate the role of calcium channel (CC) in the center-mediated regulation of renal function the effects of intravenous (iv) and intracerebroventricular (icv) administration of agnoist and blocker of the chan- nel on rabbit renal function, and their interactions were investigated. A CC blocker, verapamil, when given iv, elicited slight increases in rates of urine flow and electrolytes excre- tion for 10 min following the administration. When larger doses were given, the diuretic and natriuretic effects became less marked because of decreased renal hemodynamics due to severe hypotension. As to the mechanism of the action, direct inhibition of distal tubular reabsorptive mechanism was suggested. When given icv, Bay K 8644, a CC agonist, elicited antidiuresis in roughly dose-dependent manner, but verapamil produced diuresis and natriuresis during 20 min immediately following the administration. The release of natriuretic humoral factor was suggested as the mechanism of natriuresis. However, the possibility of direct renal tubular action of the agents which have might have leaked into the systemic circulation from the site of icv administration seemed unlikely but could not be completely ruled out. When Bay K 8644 was given icv after icv verapamil, the verapamil-induced diuresis and natriuresis was sig- nificantly depressed, whereas the antidiuresis elicited by Bay K 8644 unfolded itself either undiminished or some- what augmented in the later stage of experiment. From these results, it is suggested that changes in the state of calcium channel in brain may influence renal function, I.e., opening the calcium channel may elicit antidiuresis, whereas closing it may result in natriuresis, and that calcium channel in brain might play a role in the center-mediated regulation of renal function. |
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