[Electrocardiographic changes in the rat induced by digitalis glucosides]

Electrocardiographic changes induced by desacetil-lanatoside C and digitoxin, administered intravenously, have been studied in 25 anesthetized rats. No differences were observed between the actions of the two glucosides. Their negative chronotropic action can be effected with two mechanisms: one indirect, through vagal reflex, therefore immediate and, in general, brief; one direct, for direct action on the heart, which is gradual and long lasting. Their action on the a-v conduction is recorded by a rise in the duration of the P-Q tract, or, for higher doses, by blocking fenomena, which are brief and completely reversible. Signs of subendocardial damage are often observed, these too brief. The appearance of extrasystoles is rare.