[Role of paraventriculo-spinal pathway in the inhibition of renal sympathetic nerve activity induced by blood volume expansion in rabbits].

In anesthetized and bilateral sinoaortic denervated rabbits with either intact orascorbic acid injected paraventricular nucleus(PVN),the inhibition of renal sympathet.ic nerve activity(RSNA)induced by blood volume expansion(VE)all decreased by approximately 48 %. However, 3-4h and 3-4d after kainic acid lesion of PVN, theinhibition of RSNA was attenuated respectively to-28.0±4.5% and-25.7 f4.1%(P0.05) with considerably shortened time course (P0.01). Also such inhibition could be significantly attenuated (P0.05) by intrathecal injection of vasopressinergic V1 receptor antagonist in spinal T10-T12 segments. There was no significantdifference with the slight and brief increase of mean arterial pressure induced by VE inthe control and the experimental group.Thus it can be concluded that the inhibition ofRSNA induced by VE is partly mediated by a vagal afferent triggered PVN-spinal pathway.