title: Rapid cooling contracture in frog striated muscles treated with chlorpromazine and haloperidol.
abstract: Rapid cooling contracture (RCC) was observed in frog toe muscles pretreated with caffeine, chlorpromazine (CPZ), or haloperidol (HPD). During rapid cooling contracture in the presence of caffeine (caffeine-RCC) tension developed to more than 0.8 of the maximum tetanic tension (P0). CPZ inhibited twitch but induced rapid cooling contracture (CPZ-RCC) between 50 and 150 microM; the tension saturated at the level of 0.75 P0 at 100 microM. HPD also inhibited twitch and induced rapid cooling contracture (HPD-RCC) at concentrations greater than 25 microM; the maximum tension was 0.25 P0. In the presence of dantrolene (10 microM), the tension during CPZ-RCC was reduced by 40%. Procaine (0.25%) reduced the CPZ-RCC tension by as much as 60%. These results suggest that CPZ and HPD induced rapid cooling contracture by reducing Ca2+-accumulation in sarcoplasmic reticulum.
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002746:Chlorpromazine / Q000494:pharmacology*; D003080:Cold Temperature; D003620:Dantrolene / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology*; D009119:Muscle Contraction; D009132:Muscles / Q000187:drug effects* / Q000502:physiology; D011343:Procaine / Q000494:pharmacology; D011898:Ranidae; D013997:Time Factors; D014034:Toes
chemical_list: D002110:Caffeine; D011343:Procaine; D003620:Dantrolene; D006220:Haloperidol; D002746:Chlorpromazine