[Role of rostral ventrolateral medulla in the pressor response to intracerebroventricular injection of neostigmine].

Experiments were carried out on 47 urethane-chloralose anesthetized and flaxedil immobilized rabbits under artificial respiration. Intracerebroventricular injection (ICV) of neostigmine (100 micrograms/200 microliters) caused a marked increase in blood pressure (BP), left ventricular pressure (LVP) and renal sympathetic nerve discharge (RND), while femoral blood flow (FBF) and conductance (COND), were decreased and the heart rate (HR) was initially reduced and then slightly increased. Microinjection of atropine (0.25 micrograms/site) into the rostral ventrolateral medulla (rVLM) caused a decrease in BP, HR, RND and LVP and a increase in FBF and COND. Pretreatment of atropine injection into rVLM before ICV of neostigmine blocked the pressor response of neostigmine. These results indicate that rVLM is important for the pressor response to ICV neostigmine, which may be mediated via cholinergic muscarinic receptors in rVLM.