Increased concentration of plasma cyclic GMP from aconitine-induced atrial fibrillation in dogs and patients with paroxysmal atrial fibrillation.

The concentrations of plasma cyclic nucleotides in patients with atrial fibrillation and in dogs with aconitine-induced atrial fibrillation were measured. Radioimmunoassay was used for the determination of cyclic nucleotides. The concentration of plasma cGMP in dogs with aconitine-induced atrial fibrillation was significantly elevated at 30 and 60 min after the onset of atrial fibrillation, whereas that of plasma cAMP showed no significant changes. After the injection of atropine in dogs with atrial fibrillation and with increased plasma cGMP, the plasma levels decreased to the normal level at 60 min after the conversion to sinus rhythmus. In patients with paroxysmal atrial fibrillation, a significantly increased concentration of plasma cGMP was demonstrated on attacks of atrial fibrillation compared with those with sinus rhythmus, but no significant changes of plasma cAMP levels were observed in these patients. Thus, these results showed that the enhanced parasympathetic nervous activity had been maintained by the atrial fibrillation.