Age-Dependent Effects of NO on Rhythmic Activity of Postganglionic Sympathetic Fibers.

We studied the effects of exogenous NO donor (sodium nitroprusside) and NO synthesis blocker (100 µM L-NAME) on baseline electrical activity of postganglionic fibers in the sympathetic superior cervical in rats during postnatal ontogeny. Starting the age of 20 days, sodium nitroprusside increased the mean discharge amplitude and the spectrum power in the respiratory (0.7-1.5 Hz) and cardiac (4-7 Hz) frequency bands. In contrast, application of L-NAME for 1 h decreased the spectrum power in these bands. Both agents produced no significant effect on the rhythmic sympathetic discharges at frequencies >8 Hz.