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Ourpresent works aimed at the regulatory role of vagus nerve in a functional network of hippocampalcardiovascular-respiration.The experiments were performed on SD adult male rats, weighting 150-200 g, under the anaesthesia of 10% urethane (1 g/kg).Bilateral hippocampal unit discharges, left femoral arterial blood pressure and respiratory movement were simultaneously recorded with a four-channel data acquisition and analysis system (RM6240, China).Bilateral cervical vagus nerves were cut and unilateral central ending of it were repeatedly stimulated (10 V, 0.2 ms, 15 Hz).The tip positions of the glass microelectrodes in the hippocampiwere identified with the stain methods of pontamine sky blue at the end of experiment.The results exhibited that the coupling events were detected under the condition of intact or cut vagus nerves.The events comprised hippocampal unit aflerdischarges, enhanced breathing strength and systemic blood pressure falling.Before and during the events the interspike intervals (ISI) of hippocampal unit afterdischarges decreased from (236.5957±20.6696) s to (56.7901±4.7747) s (t=8.476, P<0.001, n=247,247);the strength of breathing enhanced from (0.3383±0.0025) g to (0.3495±0.0018) g (t=3.612, P<0.001, n=96,135);and systemic blood pressure falling from systolic pressure of (109.57±0.2523) mmHg to (106.31±0.2715) mmHg (t=17.078, P<0.000, n=285,285) and diastolic pressure of (66.13±0.1425) mmHg to (62.96±0.1602) mmHg (t=25.619, P<0.000, n=285,285).The changes of each component within the events were strengthened by stimulating unilateral vagus nerve.Before and during the events ISis of hippocampal unit afterdischarges decreased from (410.0012±18.9365) s to (54.9123±2.9068) s (t=I 8.900, P<0.001, n=622,648);the strength of breathing enhanced from (0.3108±0.0014) g to (0.3439±0.00126)g (t=l 7.311, P<0.001, n=315,424);and systemic blood pressure falling from systolic pressure of(100.8618±0.1778)mmHg to (95.339±0.2098) mmHg (t=24.318, P<0.000, n=737,737) and diastolic pressure of (59.2757±0.1194)mmHg to (54.3101±0.1449) mmHg (t=38.049, P<0.000, n=737,737).It indicated a functional network coupling of hippocampal neuronal discharges with cardiovasculatory-respiratory activities.The coupling genesis may not be related to intact vagal function, but the event strength was regulated by electrical overactivation of vagus nerve.It might be used to interpret some mechanisms of body functions under physiological or pathophysiological conditions, e.g.epilepsy-related cardiovascular-respiratory events.