1. Injection of the neurotoxin kainic acid into the region of the A1 noradrenergic neurons in the caudal ventrolateral medulla of rabbit increases blood pressure by 35 mmHg and plasma vasopressin five fold.
2. After cervical spinal cord transection or intravenous injection of phentolamine, kainic acid injected into the A1 area still elevates arterial pressure.
3. The increase in blood pressure produced by injection of kainic acid into the A1 area of the intact rabbit is almost completely reversed by the administration of a vasopressin antagonist.
4. A1 noradrenergic neurons tonically inhibit the release of vasopressin and the amount of vasopressin released by destruction of these cells is sufficient to elevate arterial pressure.
5. Imbalance within the central nervous system can produce hypertension by means of vasopressin release.