Cardiac Pacemaking: An Obligatory Role of Catecholamines?

Abstract

A relatively simple hypothesis which accounts for the basic features of pacemaking can be constructed from several important clues. The mechanisms considered here in man and dog, offer avenues of approach to solutions of the 2 mysteries of pacemaking, the origin of spontaneous activity and the manner in which the spontaneous activities of individual pacemaking cells are coordinated to produce a synchronous output to the heart. Implicit in these mechanisms is a possible basis for understanding the genesis of some cardiac arrhythmias. If experience is a guide, the specific mechanisms considered here may ultimately be proved invalid. Alternative proposals which are broadly consistent with available data are lacking at present. It seems reasonable to suggest that these mechanisms be considered as tentative working hypotheses, open to experimental confirmation or refutation.