Involvement of renal dopaminergic system in experimental neurogenic arterial hypertension

The effect of chronic salt loading (10 g of NaCl for a period of 7 days) on urinary dopamine release has been investigated in 3 groups of beagle dogs: normotensive dogs (group 1: n = 7), and 2 groups of dogs made hypertensive by chronic sinoaortic denervation [group 2: (n = 6) during the first 4 months after sinoaortic denervation i.e. a model of arterial hypertension with high levels of plasma catecholamines and group 3: (n = 6) one year after denervation i.e. a model of arterial hypertension with normal sympathetic tone]. In normal dogs (group 1), salt loading induced an increase in urinary dopamine excretion during the two first days after salt loading. The rise in urinary dopamine was blunted in group 2. It was not observed in group 3. Salt loading failed to change arterial pressure and heart rate in the three groups of animals. These data show an alteration of the renal dopaminergic system in hypertensive sinoaortic denervated dogs suggesting that a dopaminergic impairment can appear during the development of arterial neurogenic hypertension.