[Mode of action of purinergic derivatives of adenine on auriculo-ventricular conduction. Experimental study in dogs].

The effects of three purine derivatives of adenine, adenosine triphosphate (Striadyne), purified adenosine triphosphate and adenosine, on conduction tissue, were studied in closed chest dogs with endocavitary recording catheters. The dogs were anaesthetised with pentobarbital and ventilated, then three bipolar catheters were positioned to allow atrial pacing and recordings of atrial and His bundle potentials. The purines studied were administered by rapid bolus intravenous injection. The dosage was identical based on a predetermined dose-response curve (dose of 2 mg/kg). The study of the effects on atrioventricular conduction was carried out before and after administration of antagonists: atropine, 0.08 mg/kg and aminophylline, 10 mg/kg. Twelve dogs were studied for each purine: 6 with initial premedication with atropine and then aminophylline, and 6 with the inverse sequence. Lengthening of AV conduction was due exclusively to nodal depression. No variation in the HV interval was observed (HV = 35 +/- 4 ms). Lengthening of AH interval was observed very soon after injection of the drugs (5 to 10 seconds) with a peak effect between 20 and 40 seconds. Reversion to the initial value always occurred in under 2 minutes. In the model studied, Striadyne and purified adenosine triphosphate were much more powerful than adenosine, both in intensity and duration; high degree AV block was obtained in 10 out of 12 cases with Striadyne and in 8 out of 12 cases with purified adenosine triphosphate, but in only 2 out of 12 cases with adenosine. The use of specific antagonists demonstrated the different modes of action of the three purines.(ABSTRACT TRUNCATED AT 250 WORDS)