[Histamine as modulator of potassium currents in ventricular cells isolated from heart of guinea pig. A possible regulator effect of ventricular electric activity].
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.
Valenzuela
F
F
Zhou
L
L
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D004594:Electrophysiology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D011188:Potassium / Q000502:physiology*; D016276:Ventricular Function
D006632:Histamine; D011188:Potassium
La histamina como moduladora de corrientes de potasio en células ventriculares aisladas del corazón del cobayo. Un posible efecto regulador de la actividad eléctrica ventricular.