The present study was undertaken to observe the effect of picrotoxin(PT) injection into lateral ventricle (LV) on cardiac contractility (CC) and renal nerve discharge (RND).lt was found that PT injection into LV caused CC and RND to increase significantly, and this effect was dose-dependent.The effect of baroreflex on cardiovascular response produced by PT injection was also observed. Data suggested that PT injection into LV still caused CC and RND to increase when the buffer nerve was sectioned. The magnitude of increase was significantly larger than that of the intact buffer nerve. The results indicate that in the CNS, the block of gamma-aminobutyric acid (GABA) transmitter system not only could cause blood pressure and heart rate to increase, but also strengthen CC and RND; baroreflex could partly suppress cardiovascular response caused by PT injection.

Twenty cats were anesthetized and divided randomly into 3 groups: hemorrhagic shock (HS), electrical stimulation of the hypothalamic paraventricular nucleus (ESPVH) and hemorrhagic shock with addition to electrical stimulation of PVH (HS+ESPVH), so as to observe the change of plasma AVP during experimental period. The results showed that plasma AVP was increased to peak in the initial 5 min in all 3 group animals, and their values were 336.3?62.2 pg/ml (P