Effect of dopamine on the inward membrane currents of the sinoauricular fibers of the frog heart.
Dopamine increased the slow inward current in the cardiac preparation after blocking (with tetrodotoxin) or eliminating (with Na+-free perfusion) of the "fast Na+ channel". Dopamine was, however, ineffective, if the "slow channel" was blocked (by MnCl2 or D-600) or eliminated (by Ca2+ free perfusion). This adrenaline-like effect of dopamine was prevented by beta-adrenergic blockade (pindolol) and was not modified by previous depletion of tissue catecholamine stores (pretreatment with reserpine). Our data suggest that dopamine affects cardiac electrogenesis through beta-adrenergic receptors and any dopamine-induced noradrenaline release may be only of secondary importance beside this direct agonistic effect.
K
K
Kelemen
R
R
Marko
V
V
Kecskemeti
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004298:Dopamine / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism; D010869:Pindolol / Q000494:pharmacology; D011893:Rana esculenta; D012110:Reserpine / Q000494:pharmacology; D012849:Sinoatrial Node / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
D007473:Ion Channels; D013779:Tetrodotoxin; D012110:Reserpine; D012964:Sodium; D010869:Pindolol; D002118:Calcium; D004298:Dopamine; D004837:Epinephrine