Differential effects of histamine on left and righ guinea-pig atria.
In electrically stimulated strip from right guinea-pig atria histamine produced a positive inotropic effect and it increased the amplitude and duration of calcium-dependent slow action potentials, which suggests an increase in the slow inward current. These effects were apparently mediated by H2-receptors. On strips from left atria histamine produced an H1-receptor mediated positive inotropic effect, without alteration of slow action potentials. The mechanism of this positive inotropic effect remains unknown.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002927:Cimetidine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007839:Functional Laterality; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects
D002927:Cimetidine; D006632:Histamine; D003000:Clonidine