[Effect of somatostatin on the chronotropic effect caused by vagal nerve stimulation by a single stimulus]

In anesthetised cats, vagal stimulation with a single pulse burst evoked a negative chronotropic effect. Somatostatin prolonged the baseline cardiac cycle, diminished inhibitory tonic vagal effect, and increased irs latency. This peptide effect was associated with a narrowing of an area in the cardiac cycle over which even small vagal burst produced a sharp alteration of the sinus node responsiveness to vagal influences.