Neurogenic contractions of the rat tail artery under isobaric conditions: effect of transmural pressure and function of the endothelium]

In stimulation of the rat nerve with a modulated sine pattern, an increase in the modulating frequency from 0.03 to 0.15 Hz diminished the latency between the stimulating signals and changes in the vessel resistance as well as the amplitude of the flow oscillations, but did not affect tonic contractions of the vessel. A reduction of transmural pressure from 80 to 40 mm Hg increased both the tonic and the phasic components of the vessel contraction. Following the endothelium removal no change in the response latency occurred. The data obtained suggest that, during a rhythmic neurogenic influence, the vascular endothelium may work as an "amplifier" of the vessel's phasic contractions.