Alpha- and beta-adrenergic receptor stimulation in cultures of beating rat heart cells and its effect on automaticity and cyclic AMP levels.

Positive chronotropic responses were elicited in rocker cultures of beating ventricle cells of 1 to 4-day old rats by both alpha- and beta-adrenergic receptor stimulation. Only the beta and not the alpha-adrenergic receptor-mediated increase in automaticity was associated with a rise in the level of cyclic AMP in the cultures.