Effects of intraventricular and intraspinal 6-hydroxydopamine on blood pressure of DOCA-saline hypertensive rats.

The effects of intraventricular and intraspinal administration of 6-hydroxydopamine (6-OH-DA) on the development and maintenance of DOCA-saline hypertension in rats have been investigated. Intraventricular administration of 6-OH-DA prevented the development of DOCA-saline hypertension in rats, but was ineffective in developed DOCA-saline hypertension. Treatment with intraventricular 6-OH-DA on rise in blood pressure was not secondary to a reduction in salt intake, however, since vehicle-treated rats given a similar reduced salt intake became fully hypertensive. The development of DOCA-saline hypertension was unaffected by pretreatment with intraspinal administration of 6-OH-DA, which produced a virtually complete loss of noradrenaline only in the spinal cord. It is suggested that brain adrenergic neurones may participate in the production of DOCA-saline hypertension but the noradrenergic projections in the spinal cords are not essential for this process.