The effects of intraventricular administration of norepinephrine on vasogenic edema

The effects of intraventricular application of norepinephrine (NE) on the development of vasogenic edema was studied in mongrel dogs randomly divided into a control and an experimental group (NE group). Vasogenic edema was produced by infusion of a 2.0 M NaCl solution (hypertonic saline) unilaterally into the carotid artery. NE (40 micrograms/kg) was injected into the lateral ventricle 30 minutes before the infusion of hypertonic saline, after which intracranial pressure (ICP) and systemic blood pressure were continuously recorded. The animals were sacrificed 2 hours after the infusion of hypertonic saline and brain tissues were sampled from both hemispheres for measurement of the water content. Infusion of hypertonic saline produced a marked increase in ICP in the control group and a lesser increase in the NE group. The mean ICP in the control group was significantly higher (p less than 0.01) than that of the NE group from 30 to 120 minutes after saline infusion. The water content of the saline-infused hemisphere was significantly higher than that of the contralateral hemisphere in the control group, whereas the difference was not significant in the NE group. These results suggest that intraventricular administration of NE may protect against the development of intracranial hypertension due to vasogenic edema.