Hyperresponsiveness of cardiac muscles to histamine in reserpine-treated guinea pigs.
The hyperresponsiveness of cardiac tissue to histamine following treatment with reserpine was pharmacologically characterized. Guinea pig hearts were isolated 24 hours after intraperitoneal administration of 5 mg/kg reserpine. This treatment resulted in a complete depletion of tissue norepinephrine. Reserpine treatment potentiated the positive inotropic response of isolated perfused hearts to histamine at doses ranging from 0.3 to 3 micrograms (23 to 57% increase for reserpine-treated animals vs. 14 to 32% increase for control animals). Isolated left ventricular papillary muscle of reserpine-treated guinea pig hearts also showed hyperresponsiveness to histamine at concentrations of 0.1 microM or greater. The hyperresponsiveness of the papillary muscle contraction of the reserpine-treated animals to histamine was abolished in the presence of 1 microM cimetidine, but not attenuated in the presence of 1 microM diphenhydramine. This hyperresponsiveness was not modified by 1 microM bunazosin or 1 microM propranolol. The results suggest that H2-receptor mediated action plays a role in the hyperresponsiveness of cardiac muscles to histamine.
Okazaki
N
N
Department of Pharmacology, Tokyo College of Pharmacy, Hachioji, Japan.
Tanonaka
K
K
Nasa
Y
Y
Takagi
N
N
Yamasaki
T
T
Yoshida
S
S
Takeo
S
S
D000818:Animals; D015536:Down-Regulation; D004357:Drug Synergism; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D010210:Papillary Muscles / Q000187:drug effects*; D011968:Receptors, Histamine / Q000187:drug effects; D012110:Reserpine / Q000494:pharmacology*
D011968:Receptors, Histamine; D006632:Histamine; D012110:Reserpine; D009638:Norepinephrine