[The central mechanism of pressor response induced by infusing 7.5% sodium chloride solution in hemorrhagic hypotension dog].

Nine pairs of dogs were operated with head cross circulation and four pairs of dogs with brain cross circulation. Bleeding of formoral artery decreased the mean arterial pressure to 5.33 kPa and maintained for 30 min. In each pair of A dog 10% of total blood lose was infused intravenously by 7.5% NaCl solution (as test) or normal saline (as control), but B dog was not treated. The results showed that in the test group the arterial blood pressure recovered immediately in both A and B dogs and lasted for more than 60 min after infusion. The recovery value of systolic pressure was higher than diastolic pressure and pulse pressure increased. In the control group the blood pressure recovered slightly but of no statistical significance. There was no remarkable difference in heart rate between the two groups. A marked decrease in hematocrit appeared after bleeding and infusion, but there was no significant difference between the two groups (P > 0.05). Plasma sodium increased significantly after infusion in A dogs of the test group (P < 0.01), but the change in B dogs was the same in the control group. These results mentioned above indicate that the central nervous system plays important role on the mechanism of pressor response induced by infusing 7.5% NaCl solution in the hemorrhagic hypotension dog.