EFFECTS OF INTRAVENTRICULAR AND INTRASUPRAOPTIC NUCLEI INJECTION OF NEOSTIGMINE AND HEXAMETHO NIUM ON VAGO-PRESSOR RESPONSE IN RABBITS

46 urethane anaesthetized and artificially ventilated rabbits were used inthe experiment.The head of the animal was placed in a stereotoxic apparatusand according to the Saywer’s atlas,a microsyringe with a sharp tip was insertedinto the lateral ventricle and supraoptic nuclei for injection of the drugs.Theblood pressure of the left cervical artery was recorded and the changes of pressor-response before and after drug injection were compared.It was observed thatinjection of neostigmine potentiated the vago-pressor response while injection ofhexamethonitum reduced it.The result supports the hypothesis that vago-post-pituitary pathway involving acetylcholine transmitter plays an important role inthe pressor response.