[Effects of hypocalcemia on atrioventricular conduction compared with those of agents which inhibit the slow channel (author's transl)].

1. The effects of experimental hypocalcemia were studied on 13 anesthetized and atropinized dogs, measuring endocavitary His bundle recordings, global effective refractory period (ERP) (determination by the extrastimulus method), and sinus rate. These data, including arterial pressure, were observed during a 40 min. I.V. infusion of Na EDTA, 3 mg . kg-1 . min-1. We observed: 1.1. A decrease in serum ionized calcium, from 45,7 mg . 1-1 (control) to 28,1 mg . 1-1 1.2. A moderate, though highly significant, decrease in the intraatrial conduction time (SA interval of His bundle recordings). 1.3. A significant increase in the AV node conduction time (AH). 1.4. No significant change in the His-Purkinje system conduction time (HV). 1.5. A significant increase in the global ERP, primarily involving the atrial contractile tissue ERP, and further the atrioventricular node ERP.