Objective: Inhibition of calcium entrance may prevent vasospasm after subarachnoid hemorrhage. Nimodipine is a calcium channel blocker with high cerebrovascular selectivity. Amiodarone, known as a systematic vasodilator, also has calcium channel blocking effect. This study aims to compare the effects of nimodipine and amiodarone on periarterial blood induced vasoconstriction

Materials-Method: In this study, 120 hybrid, albino, male rabbits were used. Animals were randomly divided into two groups, then these two groups were further divided into 5 subgroups, on the basis of follow-up duration. Following the exposure of common carotid arteries (CCAs), in the study group a mixture of autologous blood- polyvinyl alcohol (PVA) and in the control group a mixture of saline-PVA were applied around the vessel, periadventitially. All subjects were sacrificed at the end of the pre-determined follow-up period; CCAs were prepared in the shape of helical strips. Noradrenaline induced contractile activity of the vessel samples placed in organ bath were measured with or without adding nimodipine and amiodarone and recorded using a Grass polygraph.

Findings: Contractile activity seemed to decrease in both groups, significantly in the study group. Amiodarone seemed to inhibit the contractions in a gradually increasing manner in the study group, and in a gradually decreasing manner in the control group. Nimodipine inhibited the contractions more in the study group compared with the control group. Nimodipine seemed to be more effective in the first half and amiodarone in the latter half of contact time to the blood.

Conclusion: These results suggest that both amiodarone and nimodipine are effective in preventing vasosapasm, amiodarone being more effective in vessels that were in longer contact with blood than nimodipine.

Keywords: Amiodarone, cerebral vasospasm, nimodipine, subarachnoid hemorrhage