Changes in cerebrospinal fluid volume and cardiovascular functions induced by intraperitoneal injection of hypertonic...

The present experiment was undertaken to study the relationship between hemodynamic changes and intracranial hemorrhage induced by intraperitoneal injection of large doses of hypertonic glucose solution in rats. A fifty per cent glucose solution was intraperitoneally injected at a volume of 3.5 ml/100 g b.w. into Wistar rats anesthetized with urethanechloralose. The time span from the start of injection to death was expressed in terms of 100% corrected death time (100% DT) for each rat. Saline that was added to the cerebrospinal fluid in the brain ventricle disappeared gradually from 30% DT up to death. Blood colloid osmotic pressure was slightly elevated temporally 5 minutes (7% DT) after intraperitoneal injection of the glucose solution and returned to the former level 5 minutes later. With regard to hemodynamic changes, a decrease in blood pressure and heart rate began to occur between 5-10% DT. Thereafter, blood pressure and heart rate decreased significantly as compared with the pretreatment period, and the plasma levels of both epinephrine and norepinephrine showed sharply increasing curves as time elapsed after the intraperitoneal injection of the hypertonic glucose solution. It was suggested that the decrease in cerebrospinal fluid and the fall in blood pressure were related to the movement of water from the brain and the flow of body fluid into the hypertonic blood plasma which caused an enlargement of the ventricles due to brain reduction and a change in circulating blood volume. However, questions still remain concerning the mechanisms of the marked increase in plasma catecholamines and bleedings which occurred only in the subarachnoideal space and ventricles.