title: Post-extrasystolic potentiation; effect of Ca, histamine, caffeine and epinephrine.
abstract: The influence of caffeine, epinephrine, histamine and high Ca solutions on post-extrasystolic potentiation of guinea-pig's isolated heart muscle was investigated. It was found that caffeine suppressed the potentiation process while epinephrine and high Ca solutions enhanced it. Histamine caused a gradual decrease in post-extrasystolic potentiation. The results support the view that the potentiation process is related to an increased Ca release by the terminal vesicles caused by paired stimulation.
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D005117:Cardiac Complexes, Premature / Q000503:physiopathology*; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*
chemical_list: D002110:Caffeine; D006632:Histamine; D002118:Calcium; D004837:Epinephrine