Effect of adenosine on electrical activity in guinea-pig atrium

Adenosine abolished action potentials and slowed down depolarization in the sinus node cells, and depressed the slow component in the working fibers. Noradrenaline and dibutryl cAMP did not counteract the effects of adenosine in the working myocardium whereas in the pacemaker, dibutryl cAMP alone evoked low frequency spontaneous activity.