Pathophysiological role of dopamine on the development of hypertension in rats.

The aim of the study is to investigate the pathophysiological role of dopamine (DA) in the development of hypertension in DOCA-salt hypertensive rats and spontaneously hypertensive rats (SHRs). The augmentation of dopaminergic activity by chronic administration of bromocriptine, a DA agonist, suppressed the increase of blood pressure in DOCA-salt hypertensive rats. In contrast, suppression of dopaminergic activity by chronic administration of carbidopa, an inhibitor of dopa decarboxylase, accelerated the development of hypertension in SHRs, and this acceleration was also increased by salt loading. Increased urinary excretion of norepinephrine (NE) by DOCA-salt treatment was suppressed by the treatment of bromocriptine. In contrast, administration of carbidopa and salt loading in SHRs resulted in an increase in renal NE content and in urinary NE and epinephrine (E) excretion and a decrease in urinary sodium excretion. These results suggest that dopaminergic activity participate in the development of hypertension and decreased dopaminergic activity accelerates the development of hypertension in hypertensive rats mainly through the enhancement of peripheral sympathetic nerve activity.