To evaluate the role of the vagal afferents in the generation and formation of high frequency oscillation (HFO), effect of selective electrical stimulation of A?-? afferent fiber groups of the vagus nerve (0.4-0.5 V, 0.1ms, 5-160 Hz), applied at three respiratory phases: inspiratory phase (IS), expiratory phase (ES), and continuous phase throughout both IS and ES (CS), on the phrenic HFO was quantitatively assessed on ether-anesthetized, vagotomized, paralyzed and artificially ventilated rabbits. After calculation of the power spectrum of the efferent phrenic nerve activity, the mean square values (MSV), representing total amount of HFO-output, and the peak frequency of the HFO were estimated by means of curve-fitting method. Regardless of the mode of the stimulation, the MSV decreased in a stimulus-frequency dependent fashion. The CS was most potent, then IS, and ES was less effective, though the reduction was significant (p

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