Histamine as modulator of potassium currents in ventricular cells isolated from heart of guinea pig. a possible regulator effect of ventricular electric activity
Valenzuela, F.; Zhou, L.
Gaceta Medica de Mexico 128(4) 403-409; Discussion: 409-410
1992
ISSN/ISBN: 0016-3813 PMID: 1307989 Document Number: 388085
Histamine is present in cardiac tissues in considerable amount, but its physiological role is not well understood. There are two kinds of histamine receptors on the cardiac cells (H1 and H2). Whereas the H2 actions are very well studied little is known about H1 effects. It has been reported that stimulation of H1 receptors induce a shortening of the action potential as a decrease in excitability, but the ionic mechanisms responsible for these are not known. The aim of the present paper is to explore the possible ionic mechanisms related to these effects on isolated ventricular myocytes by means of voltage clamp technique. Histamine induced a shift in the current-voltage relationship of the potassium background current to the right. This shift implies an increase in outward current at the plateau level, responsible for the shortening, as well as for the decrease in excitability. This is, as far as we know, the first report in potassium background channel modulation by an endogenous substance and firmly support the hypothesis that histamine is playing a role in cardiac modulation.