title: Different effects of L-type and L+N-type calcium channel blockers on hamster cheek pouch venules.
abstract: Dihydropyridine calcium channel blockers are not uniform in terms of their action on calcium channel. L-type calcium channel blockers dilate the resistance arterioles. Cilnidipine is a dihydropyridine calcium channel blocker that also acts on N-type calcium channels, and may dilate venules through its effect on the sympathetic receptor. The influence of an L-type calcium channel blocker (nifedipine) or this L+N type blocker at 10(-7) mol to 10(-4) mol on venular diameter was examined by superfusion of male Syrian hamster cheek pouches. Nifedipine dose dependently dilated the arterioles alone, whereas cilnidipine dilated both arterioles and venules. Application of 10(-7) mol omega conotoxin, an inhibitor of N-type channels, after nifedipine led to significant dilation of venules, while it had no influence when administered after cilnidipine. These findings indicate that the effects of calcium channel blockers on the venules differ according to the action on N-type calcium channels, and that cilnidipine (an L+N type calcium channel blocker) dilates venules through its additional action on N-type channels.
authors.affiliation: Department of Cardiology, Nihon University Surugadai Hospital, Tokyo, Japan. kushiro@med.nihon-u.ac.jp
authors.forename: Toshio
authors.initials: T
authors.lastname: Kushiro
authors.forename: Nagaoki
authors.initials: N
authors.lastname: Watanabe
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Takahashi
authors.forename: Miyuki
authors.initials: M
authors.lastname: Koike
authors.forename: Fumio
authors.initials: F
authors.lastname: Saito
authors.forename: Yuji
authors.initials: Y
authors.lastname: Otsuka
authors.forename: Katsuo
authors.initials: K
authors.lastname: Kanmatsuse
mesh_terms: D000818:Animals; D001160:Arterioles / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D020864:Calcium Channels, N-Type / Q000187:drug effects*; D006224:Cricetinae; D004095:Dihydropyridines / Q000494:pharmacology; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa / Q000098:blood supply* / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D014699:Venules / Q000187:drug effects; D020960:omega-Conotoxins / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D020864:Calcium Channels, N-Type; D004095:Dihydropyridines; D020960:omega-Conotoxins; C065927:cilnidipine; D009543:Nifedipine