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Inotropic effects of histamine in human myocardium: differentiation between positive and negative components.
- Source :
-
Journal of cardiovascular pharmacology [J Cardiovasc Pharmacol] 1984 Nov-Dec; Vol. 6 (6), pp. 1210-5. - Publication Year :
- 1984
-
Abstract
- Histamine is known to enhance the contractility of the human myocardium in vitro. We have observed that when the H2-receptor antagonist cimetidine (or ranitidine) blocks the positive inotropic effect of histamine in spontaneously beating pectinate muscles isolated from human right atrial appendage, a negative inotropic effect is unmasked. This decrease in contractility is independent of changes in rate, as it occurs in preparations paced at constant rate, is mimicked by the H1-receptor agonist 2-(2-thiazolyl)-ethylamine (ThEA) and is abolished by the H1-antagonist pyrilamine. Thus, the negative inotropic effect of histamine appears to be mediated by H1-receptors. Our data indicate that the inotropic response of the human myocardium to histamine consists of two opposing components: an increase in contraction, mediated by H2-receptors, and a decrease in contraction, mediated by H1-receptors. Given the widespread use of H2-blockers and the multitude of clinical conditions in which histamine is released, there may well be circumstances in which an H1-response predominates. This could result in a decrease in myocardial contractility.
- Subjects :
- Cimetidine pharmacology
Humans
Imidazoles pharmacology
Impromidine
In Vitro Techniques
Norepinephrine pharmacology
Pyrilamine pharmacology
Ranitidine pharmacology
Receptors, Histamine H1 drug effects
Receptors, Histamine H2 drug effects
Thiazoles pharmacology
Time Factors
Histamine pharmacology
Myocardial Contraction drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0160-2446
- Volume :
- 6
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Journal of cardiovascular pharmacology
- Publication Type :
- Academic Journal
- Accession number :
- 6084781