Acetylcholine-induced smooth muscle contraction of intrapulmonary small bronchi is augmented in antigen-induced airway hyperresponsive rats.
Smooth muscle responsiveness of intrapulmonary small bronchi obtained from repeatedly antigen-challenged rats was compared with that from control animals to determine whether smooth muscle contractility of peripheral airways is augmented by such repeated challenge. In intact (non-permeabilized) smooth muscles of intrapulmonary bronchi, the acetylcholine (ACh)-induced contractile response was significantly augmented in the repeated challenge group, although 60-mM K+-induced contraction was within the normal level. In beta-escin-permeabilized muscles, no significant difference between groups was observed in the Ca2+-induced contractile responses. Thus, augmented ACh-induced contraction of intact intrapulmonary small bronchial smooth muscle might be, at least in part, due to an enhanced ACh-mediated Ca2+-sensitizing signal.
Chiba
Y
Y
Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan. chiba@hoshi.ac.jp
Takada
Y
Y
Sakai
H
H
Takeyama
H
H
Misawa
M
M
D000109:Acetylcholine / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D000941:Antigens; D001980:Bronchi / Q000187:drug effects / Q000502:physiology; D016535:Bronchial Hyperreactivity / Q000139:chemically induced / Q000503:physiopathology*; D002118:Calcium / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D000941:Antigens; D000109:Acetylcholine; D002118:Calcium