[Effects of nicotine on the electrocardiogram of the rat]

In these experiments in the rat was studied the action of nicotine, administered intravenously in doses from 20 to 900 gamma/Kg. It was seen that, after the injection of lower doses, in the first phase there is always a more or less conspicuous diminution of the heart rate and a light and fleeting rise of the time of a-v conduction; there follows, after 25-30', a phase in which there is, as already noted, a rise of the heart rate. After higher doses was observed always an increase of the heart rate. Extrasystoles due to the action of nicotine was not observed. Sometime were observed signs of subendocardial damage or of fleeting right bundle-branch block. After a dose of 300 gamma (900 gamma/Kg) was observed a conspicuous and brief inhibition of sinus node activity and of the a-v conduction.