Noradrenaline-Induced Restoration of Acidosis-Inhibited Neurogenic Vasoreactivity at Using Different Electrical Stimulation Frequencies

Experiments using segments of the tail artery from young rats addressed the effects of noradrenaline on the neurogenic vasoconstrictor reactions of these segments evoked by stimulation with an electric field of frequencies 3, 5, 10, and 40 Hz in controls and after decreasing the solution pH from 7.4 to 6.6. Acidosis produced significant decreases in this reaction at all electrical stimulation frequencies. Noradrenaline restored neurogenic vasoconstriction after it had decreased spontaneously or after the significantly greater drop induced by acidosis. On the background of acidosis, the potentiating action of noradrenaline on neurogenic vasoconstriction was more significant than at normal pH and was more apparent at higher electrical stimulation frequencies and noradrenaline concentrations. This may be of value for redistributing blood flow to vitally important areas during muscle work, which is accompanied by acidosis, increased spike frequencies in sympathetic nerves, and increases in noradrenaline concentrations.

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