Abstract
Summary
In studies designed to investigate the effects of cholinergic stimuli on myocardial cyclic nucleotide content and myocardial performance, an isolated paced rabbit atrial preparation and an in situ rabbit right atrium/vagus nerve preparation were utilized. Following vagal stimulation or ace-tylcholine treatment, increases in atrial cGMP content preceded or occurred at the same time as the mechanical changes associated with cholinergic stimulation. Atrial cAMP content was not affected by these stimuli. Increased cGMP levels were correlated with the decreased force of contraction, but not the decreased chronotropic effects of cholinergic stimulation. These data support the concept that modifications in cardiac performance may be mediated by cGMP. In particular, cGMP may mediate the pharmacological effects of acetylcholine as well as the physiological effects of vagal stimulation.
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