Contractile response of rabbit dilator pupillae muscle to isotonic high K or norepinephrine, and Ca movement.
Isotonic 80 mM K and norepinephrine contracted the isolated dilator pupillae muscle of the rabbit. Norepinephrine-induced contraction was inhibited by papaverine, but not by Ca blockers, while K-induced contraction was abolished by removing Ca from the bathing fluid but there was a residual response to norepinephrine in Ca-free solution. These results suggest that, in the rabbit dilator pupillae muscle, K-induced contraction is mainly attributable to the increase of Ca influx, while norepinephrine-induced contraction is mainly due to the facilitation of release of intracellularly sequestered Ca.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D005711:Gallopamil / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D010208:Papaverine / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011680:Pupil / Q000187:drug effects; D011817:Rabbits
D010276:Parasympatholytics; D010880:Piperidines; D005711:Gallopamil; D010208:Papaverine; D000242:Cyclic AMP; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine