THE ACTION OF MERCURIAL DIURETICS ON THE EFFECTIVE REFRACTORY PERIOD, ELECTRICAL EXCITABILITY AND CONDUCTION VELOCITY IN THE MAMMALIAN HEART

¹ Department of Pharmacology, State University of New York, Medical Center at Syracuse University, Syracuse, New York
² Departments of Pharmacology and Medicine, School of Medicine, University of Washington, Seattle, Washington, and the Department of Pharmacology, State University of New York, Medical Center at Syracuse University, Syracuse, New York

The action of the mercurial diuretics, mersalyl and Esidron acid, on experimental auricular flutter, electrical excitability, conduction velocity and the effective refractory period were studied on the ventricle and auricle of the openchested anesthetized dog.

In auricular flutter of the circus movement type these mercurial diuretics produced a decrease in auricular flutter rate and in most instances no reversion to a normal rhythm, even with amounts close to the lethal dose.

Electrical excitability and conduction velocity in the auricle were decreased with dosages equal to 40-50 per cent of the lethal dose.

The effective refractory period was increased only with amounts of the mercurial which were nearly equal to the lethal dose.

In two out of the seven experiments auricular flutter was changed to auricular fibrillation. This fibrillation could not be reverted to a flutter or normal rhythm either by mono- or dithiols or by a number of blocking agents (atropine, tetraethylammonium chloride and Dibenamine) or by vagal or sympathetic denervation.