The Central Effects of Gabanergic Neurons on Cardiovascular Function and Body Fluid Regulation.

(1)GABA对侧脑室注射血管紧张素Ⅱ（Ang Ⅱ）、卡巴胆碱（CB）、高渗盐水（icv）、静脉注射HS或失血性休克引起的AVP释放和心血管功能的影响：Ang Ⅱ和CB均使血浆AVP和平均动脉压（MABP）升高，GABA对这些变化无影响。另一方面，GABA能明显减弱侧脑室注射HS引起的MABP和血浆AVP的升高。iv HS刺激AVP释放，但不增加MABP，GABA则减弱AVP释放。GABA不能抑制失血性休克引起的AVP释放增加。这些结果表明，GABA能神经元可抑制渗透压刺激引起的AVP释放和MABP升高，但对Ang Ⅱ、CB和失血性休克的反应无影响。(2)侧脑室注射内皮素（ET）对AVP释放和心血管功能的影响：高剂量ET刺激AVP和ANP释放，升高MABP，而低剂量ET除升高MABP外，不刺激AVP和ANP释放。这些结果表明，ET通过增加AVP释放和交感神经流出增加中枢血压。outflow.ses

(1) Effects of GABA on AVP release and cardiovascular function in response to either angiotensin II (Ang II), carbachol (CB) or hypertonic saline given intracerebroventricularly (icv) as well as to either HS given iv or hemorrhagic shock.Ang II and CB increased plasma AVP and mean arterial blood pressure (MABP), but GABA never affected these changes. On the other hand, increases in MABP and plasma AVP produced by HS given icv were apparently attenuated by GABA. HS given iv stimulated AVP release without increased MABP, and GABA attenuated AVP release. Increased AVP release induced by hemorrhagic shock was not suppressed by GABA. These results showed that gabanergic neurons may inhibit AVP release and an increase in MABP mediated by osmotic challenge, but not the responses to Ang II, CB and hemorrhagic shock.(2) Effects of endothelin (ET) given icv on AVP release and cardiovascular function.ET in the relatively high dose stimulated AVP and ANP release and increased MABP, but not these release in the low dose except increased MABP. These results showed that ET centrally increased blood pressure via increases in AVP release and sympathetic outflow.ses in AVP release and sympathetic outflow.