Participation of the nucleus locus coeruleus in DOCA-salt hypertensive rats

The locus coeruleus was subjected to biphasic electrical stimulation, and a group of deoxycorticosterone acetate (DOCA)-salt hypertensive rats revealed a greater pressor response than a group of normotensive control rats. The pressor threshold current (i.e. minimum current to raise the arterial pressure by 10 mm Hg) of DOCA-salt hypertensive rats was also lower. The threshold current was low even in the prehypertensive stage of DOCA-salt treated rats. During arterial pressure fall, the pressor threshold current lowered only in normotensive rats and neither group underwent a change during pressure rise. These data indicated that the locus coeruleus had a pressor role and it had been accelerated in DOCA-salt treated rats before hypertension was evident. Following bilateral electrical lesions of the locus coeruleus no significant differences were observed in the arterial pressure changes, while vascular reactivity to norepinephrine did not differ between the two groups. The results suggest that the locus coeruleus may be involved in the development of hypertension but may not be important in the maintenance of it.