In:
Canadian Journal of Physiology and Pharmacology, Canadian Science Publishing, Vol. 64, No. 12 ( 1986-12-01), p. 1484-1488
Kurzfassung:
The effects of histamine on the force of contraction and calcium-dependent action potentials were studied in rabbit ventricular papillary muscles. The positive inotropic effect of histamine seems to be dependent on stimulation of H 1 and H 2 receptors. The H 1 antagonist chlorpheniramine produced a competitive blockade of the positive inotropic effects of histamine. Cimetidine produced a competitive blockade, which was apparent only after blockade of H 1 receptors. Histamine increased the maximum upstroke velocity of slow action potentials. This effect can be entirely accounted for by stimulation of H 2 receptors. The phosphodiesterase inhibitor 3-isobutyl-methyl-xanthine potentiated the H 2 receptor mediated effects of histamine on the force of contraction and slow action potentials. We conclude that rabbit ventricular muscle possesses both H 1 and H 2 receptors that mediate the positive inotropic effect of histamine. The H 2 -mediated effect seems to be causally related to an increase in the calcium slow inward current and is probably linked to an enhanced cellular cyclic adenosine monophosphate content. The mechanism of the H 1 -mediated positive inotropic effect remains unknown.
Materialart:
Online-Ressource
ISSN:
0008-4212
,
1205-7541
Sprache:
Englisch
Verlag:
Canadian Science Publishing
Publikationsdatum:
1986
ZDB Id:
2004356-9
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