CARDIOVASCULAR-RESPONSES TO INTRACEREBROVENTRICULAR INJECTION OF GABAIN RENOVASCULAR HYPERTENSIVE RATS

Effects of central GABAergic stimulation on cardiovascular function we re evaluated in 2-kidney, 1-clip (2K1C) renovascular hypertensive rats (RVHR). Intracerebroventricular injection (icv) of GABA (100 and 200 mu g) reduced blood pressure (BP) to a greater degree in RVHR as compa red with sham-operated controls, and the greatest response was seen in RVHR 4 wk after operation (4 wk-RVHR). In addition, a-decreased sensi tivity of baroreflex was observed in 4 wk-RVHR, and was improved by ic v GABA. Pretreatment with icv captopril (200 mu g) only reduced BP mod erately in 4 wk-RVHR, but attenuated remarkably the depressor effect o f GABA. On the contrary, pretreatment with ip captopril was less effec tive in attenuating the depressor effect of GABA. Our results indicate d that RVHR was deficient in central inhibition on BP control, for sti mulation reduced BP to a greater degree and improves the decreased sen sitivity of baroreflex in RVHR; the depressor effect of GABA is mediat ed, at least in part, by inhibiting brain angiotensin system. Effects of on cardiovascular function were