Blood flow in the optic nervehead following intravenous administration of calcium antagonist
Noguchi, S.; Kimura, Y.; Nitta, A.; Shimizu, R.; Kobayashi, K.; Aoki, K.; Maruyama, Y.; Isono, H.; Shimizu, M.
Nippon Ganka Gakkai Zasshi 96(8): 967-972
1992
ISSN/ISBN: 0029-0203 PMID: 1519513 Document Number: 396037
The authors quantitated the blood flow of the optic nervehead after intravenous administration of calcium antagonist. The hydrogen clearance method was used to measure the blood flow after placing an electrode sensor in the optic nervehead of 9 eyes of 5 Macaca fuscata monkeys, under general anesthesia by intravenous pentobarbital sodium. 5 micrograms/kg of nicardipine, a calcium antagonist, was rapidly injected into the femoral vein. Measurement of blood flow in the optic nervehead was started 5 minutes after injection until 90 minutes at intervals of 15 minutes. A dose of 2 micrograms/kg/min nicardipine was then administered intravenously for another 90 minutes. During the experiment, intraocular pressure was maintained at 15 mmHg under continuous monitoring of systemic blood pressure. The blood flow in the optic nervehead decreased to 83% 5 minutes after injection. It increased slowly and reached the initial value 50 minutes later. It reached 108% of the initial value 80 minutes after injection. During the additional infusion of nicardipine, the blood flow decreased slowly and reached 85% of the initial value. It is concluded that the blood flow in the optic nervehead changed depending on the method, quantity and duration after injection of intravenous calcium antagonist. The blood flow decreased immediately after administration. The main cause of this phenomenon was thought to be due to decrease of perfusion pressure secondary to decrease of systemic blood pressure.