The chronotropic effect of histamine, prometasin and cimetidin on rat heart.
The effect of histamine, prometasin (the blocker of histamine H-1 receptor) and cimetidin (the blocker of histamine H-2 receptor) on the frequency of the isolated right atrium of rat was studied. Histamine, prometasin and cimentidin were applied cumulatively in concentrations of 5.4 X 10(-6) to 16.3 X 10(-3) mmol/l so that each new concentration was 3.3 times higher than the preceding one. The positive chronotropic effect of histamine was shown to be strongest with a concentration of 5.4 X 10(-3) mmol/l. Prometasin and cimentidine applied in increasing concentrations gave a negative chronotropic effect. Prometasin and cimetidin applied in a concentration of 5.4 X 10(-3) mmol/l before histamine, decreased the positive chronotropic effect of histamine to more than 60% no matter whether prometasin and cimetidin were applied alone or together. This finding suggests that the effect of histamine on rat heart is mainly realized via histamine H-1 and H-2 receptors and partly through releasing catecholamines from the adrenergic nerve terminal.
Frković
A
A
Toxicological Laboratory of the Health Center, Rijeka.
Skrobonja
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A
Atanacković
D
D
D000818:Animals; D002927:Cimetidine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D008297:Male; D011398:Promethazine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D006634:Histamine H1 Antagonists; D002927:Cimetidine; D006632:Histamine; D011398:Promethazine