The effect of cyclic-GMP in atrial fibrillation

33 THE EFFECT OF CYCLIC-GMP IN ATRIAL FIBRILLATION. T. Uno, H. Kanayama, K. Imura, K. Ogawa, T. Satake. The 2nd Department of Internal Medicine, Nagoya University School of Medicine, Nagoya, Japan. We measured plasma c-GMP concentration during high frequency atria1 pacing and atria1 fibrillation (AF) threshold following the administration of dibutyryl c-GMP (DBc-GMP) and atropine in order to study the relationship between parasympathetic nervous activity and AF. The high frequency atria1 pacing (4lO/min) was given for 1 hour in 24 dogs and the plasma c-GMF levels were measured serially by radioimmunoassay. The AF threshold in 10 dogs was measured by cardiac stimulator. The mean concentration of plasma c-GMP during high frequency AF was significantly elevated from 18.6k2.8 to 29.3k3.4 pmol/ml after 30 min (~~0.01). The threshold of AF was 6.020.1 mA before the administration of DBc-GMB and significantly decreased to 3.2kO.6 mA (~~0.05) after 1.0 mg/kg of DBc-GMP. And it significantly increased to 19.1f1.7 mA after the injection of 0.1 mg/kg atropine. Thus, the results showed that the enhanced parasympathetic nervous activity played an important role in inducing, and maintaining of AF.

34 EFFECTS OF DIBUTYRYL CYCLIC AMP AND ISOPROTERENOL ON THE ACUTELY ISCHEMIC MYOCARDIUM T.Saito, E.Tokutake, K.Hibiya, I.Watanabe, S.Saito, Y,Ozawa, M.Hatano. The 2nd Dept. of Medicine, Nihon Univ. School of Medicine, Tokyo, Japan We studied comparative effects of dibutyryl cyclic AMP (DBcAMP) and isoproterenol (ISP) on the acutely ischemic myocardium in 16 dogs. Left anterior descending artery was occluded for 10 minutes. The interstitial K+ ([K