Efferent renal nerve traffic in the spontaneously hypertensive rat.

Renal nerve activity has been recorded in anaesthetised and conscious spontaneously hypertensive rats (SHR) and normotensive control rats (WKY). SHR showed an elevated renal nerve discharge in the control situation both when mean rectified activity was measured in conscious rats and when single fibre activity was recorded in anaesthetised rats. The renal nerve response to stress was also markedly augmented in SHR, and parallel with the nerve response we observed a greater decrease in renal sodium excretion in SHR than in WKY. Baroreflex inhibition of heart rate was markedly attenuated in SHR. In contrast, baroreflex inhibition of renal nerve activity was, if anything, augmented. Left atrial receptors were reset in SHR. Interestingly enough, SHR had an augmented response to volume loading, due to a decreased distensibily of peripheral veins, which counteracted the resetting of the left atrial receptors.