Developmental changes of alpha 1-adrenergic chronotropic action on human sinus node.

The important role of alpha 1-adrenoceptors in reperfusion ventricular arrhythmia is mentioned in the introduction. However, the present report is concerned with the sinus node. It is speculated that the decreased positive chronotropic action of alpha 1-adrenergic stimulation due to aging may contribute to the development of sick sinus syndrome.