title: Effects of papaverine on twitches in mouse diaphragm.
abstract: This study examined the inhibitory effects of papaverine on twitches directly elicited by electrical stimulation of the mouse diaphragm. Papaverine (3-100 μM) inhibited twitches in a dose-dependent manner. Papaverine increased the cyclic adenosine monophosphate (cAMP) but not cyclic guanosine monophosphate (cGMP) content. IBMX, Db-cAMP and 8-br-cGMP did not affect twitches, whereas verapamil and NaCN inhibited twitches. Increases in extracellular Ca²+ removed the twitch inhibition caused by verapamil but not that caused by papaverine. Papaverine (30 and 100 μM) and NaCN (1 mM) decreased creatine phosphate and ATP contents. These results suggest that the relaxing effects of papaverine on mouse diaphragm are mainly due to inhibition of aerobic energy metabolism.
authors.affiliation: Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan. t-kaneda@nvlu.ac.jp
authors.forename: Takeharu
authors.initials: T
authors.lastname: Kaneda
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Hayasaka
authors.forename: Yuta
authors.initials: Y
authors.lastname: Nagai
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tajima
authors.forename: Norimoto
authors.initials: N
authors.lastname: Urakawa
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Nakajyo
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D003964:Diaphragm / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D010208:Papaverine / Q000008:administration & dosage / Q000494:pharmacology*; D010725:Phosphocreatine / Q000187:drug effects / Q000378:metabolism; D012966:Sodium Cyanide / Q000494:pharmacology; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D010208:Papaverine; D000242:Cyclic AMP; D006152:Cyclic GMP; D012966:Sodium Cyanide; D002118:Calcium