Effect of histamine on the small arteries in the gracilis muscle of the rabbit
Suzuki, H.; Casteels, R.
Journal of Pharmacology and Experimental Therapeutics 211(2): 430-435
1979
ISSN/ISBN: 0022-3565 PMID: 501573 Document Number: 148702
Histamine depolarizes smooth muscle cells of the small arteries in the rabbit gracilis muscle and induces a contraction. The development of this depolarization and contraction is augmented by addition of cimetidine, causing a H2-receptor blockade. If, however, the H1-receptors were blocked by mepyramine, histamine relaxed tissues which were contracted by high . In Na-deficient solution, histamine slightly hyperpolarized the cells by reducing the depolarization induced by H1-activation. The H2-activation causes hyperpolarization similar to the control. K-free solution induced a small membrane depolarization suggesting involvement of an electrogenic ion pump to the membrane potential. Activation of the H1-receptor caused, in K-free solution, a depolarization similar to the control, although an H2-stimulation failed to hyperpolarize the membrane. H1-activation enhanced the noradrenaline response, although an H2-stimulation suppressed it. The changes in membrane potential and tension development seem to be related under most experimental conditions; apparently activation of the H1- and H2-receptors can exert an important effect on the tension development through pharmacomechanical coupling, i.e., without or with limited changes of the membrane potential.