[ATP effects on eccito-conduction and arterial pressure before and after block of the vagus. Haemodynamic and...

In order to investigate the cardiovascular effects of ATP (15-30 mg) i.v. administration, 12 normal subjects, aged 27-55 yrs, were studied, during Arterial Pressure Monitoring and His Bundle Electrogram recording, using Sherlag's technique. ATP cardiovascular response was divided in the following four phases: Latency phase, Progressive Bra dyarrhythmic-Hypotensive, Maximal Inhibitor Phase, Tachyarrhytthmic Hypotensive Reflex Phase. Atropine (0.02-0.04 mg/Kg) i.v. injection did not significantly prevent ATP effects. Increasing dosage of atropine (0,06, pointed out a moderate competitive antagonism with ATP. These data suggest a possible direct action of ATP (purinergic receptors or direct membrane effect) but don't exclude an interaction with Parasympathetic system (probable purinergic neuromodulation).