• Jun-Yih Chen, Kuang-I Cheng, Yi-Lin Tsai, Yi-Ren Hong, Shen-Long Howng, Aij-Lie Kwan, Ing-Jun Chen, and Bin-Nan Wu.
• Department of Neurosurgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
• Shock. 2012 Aug 1;38(2):203-12.

AbstractAlterations in the activity of vascular K channels are commonly associated with abnormalities in cerebral vascular function after subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage-induced vasospasm remains incompletely understood; nevertheless, activation of K channels may be of benefit in relieving spastic constriction. This study was to examine whether the vasodilators KMUP-1 and pinacidil, a KATP-channel opener, have the ability to prevent SAH-induced vasospasm via the large-conductance Ca-activated K (BKCa) channels in cerebral arteries. Rats were divided into four groups including sham-operated, SAH, KMUP-1 treated, and pinacidil treated. Subarachnoid hemorrhage rats were induced by injecting autologous blood into cisterna magna, and then KMUP-1 or pinacidil (1 mg/kg) was injected intraperitoneally 1 and 24 h after SAH. Behavioral tests were assessed on day 2 after SAH before the rats were killed. Cerebral myocytes were enzymatically isolated from rat basilar arteries and used to monitor BKCa-channel activities. In isolated basilar arteries, KMUP-1-treated and pinacidil-treated rats showed normalized vascular reactivity. In whole-cell recordings, BKCa currents were attenuated in SAH rats compared with sham-operated rats. In inside-out patches, the conductance and voltage sensitivity of single BKCa-channels were unchanged among the four groups. In contrast, SAH rats showed markedly decreased BKCa-channel activity and β1-subunit expression associated Ca sensitivity that was further confirmed by immunofluorescence staining and Western blotting. Subarachnoid hemorrhage-induced deficits in motor function and BKCa-channel inhibition were improved by KMUP-1-treated and pinacidil-treated rats. In addition, SAH appears to modify BKCa-channel calcium sensitivity. KMUP-1 and pinacidil prevent SAH-induced vasospasm at least in part by the restoration of BKCa-channel activities.

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