Characterization of Ca2+ channels involved in endothelin-1-induced contraction of rabbit basilar artery.
This study attempted to characterize Ca2+ channels involved in endothelin-1-induced contraction of rabbit basilar artery using whole-cell patch-clamp and measurement of intracellular free Ca2+ concentration. Endothelin-1 activates two types of Ca2+-permeable nonselective cation channels (NSCC-1 and NSCC-2) and a store-operated Ca2+ channel (SOCC) in addition to the voltage-operated Ca2+ channel (VOCC). These channels can be discriminated using Ca2+ channel blockers, SK&F 96365 and LOE 908. Tension study was conducted to clarify the Ca2+ channels involved in endothelin-1-induced contraction of basilar artery. Endothelin-1-induced basilar artery contraction is fully dependent on extracellular Ca2+ influx. Based on sensitivity to nifedipine, an L-type VOCC blocker, VOCCs have a minor role in endothelin-1-induced contraction. Both LOE 908 and SK&F 96365 inhibit endothelin-1-induced contraction in a concentration-dependent manner, and their combination abolished it. The median inhibitory concentrations of these blockers for endothelin-1-induced contraction correlated well with those of the endothelin-1-induced [Ca2+]i responses. Thus, the inhibitory action of these blockers on endothelin-1-induced contraction may be mediated by blockade of NSCC-1, NSCC-2, and the SOCC. Extracellular Ca2+ influx through NSCC-1, NSCC-2, and SOCC may be essential for endothelin-1-induced basilar artery contraction.
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan. ykawanabe@rics.bwh.harvard.edu
Yoshifumi
Y
Kawanabe
Nobuo
N
Hashimoto
Tomoh
T
Masaki
D000818:Animals; D001488:Basilar Artery / Q000187:drug effects* / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D019332:Endothelin-1; D009543:Nifedipine