EFFECT OF DORSAL PERIAQUEDUCTAL GREY LESION ON BAROREFLEX AND CARDIOVASCULAR-RESPONSE TO AIR-JET STRESS

Certain areas within the periaqueductal grey (FAG) have been implicate d in cardiovascular regulation. The influence of excitotoxic lesions o f the caudal dorsal periaqueductal grey on the baroreceptor-heart rate reflex and the cardiovascular response to air-jet stress was examined in awake Wistar-Kyoto rats. Presser (11 +/- 2 mmHg) and tachycardic ( 25 +/- 4 beats/min) responses to air-jet were not influenced by the le sion. Similarly, the resting MAP and HR were unchanged. However, the g ain of the baroreflex was reduced from - 3.9 +/- 0.1 to - 2.8 +/- 0.3 beats/min per mmHg and the upper threshold was increased from 120 +/- 5 to 135 +/- 7 mmHg in the lesioned group. These observations suggest that although the caudal dorsal FAG does not appear to exert a tonic i nfluence on vasomotor tone or mediate the air-jet response, it may pro vide a facilitatory input to the baroreceptor-heart rate reflex.