The adrenergic innervation of arteries and veins in rats with DOCA-NaCl hypertension: the role of sodium and chloride overload.

The adrenergic innervation of major arteries and veins was examined in DOCA-NaCl hypertensive rats using a histochemical fluorescent technique to detect the intraneuronal catecholamine content. The possible role of sodium and chloride ions was studied in DOCA-treated rats which were fed a low-salt diet which was supplemented with sodium bicarbonate instead of sodium chloride. Focal defects of adrenergic innervation were observed in blood vessels of DOCA-NaCl hypertensive rats. Nevertheless, the degree of these changes differed according to the vascular bed examined. A maximum decrease of the catecholamine content in varicosities of adrenergic terminals was found in the femoral vessels while there were nearly no changes in tail arteries and veins. Adrenergic innervation was usually more impaired in veins than in corresponding arteries of hypertensive animals. Pronounced changes in blood vessels of rats with DOCA-NaCl hypertension contrasted with the maximum alterations observed in those hypertensive DOCA-treated animals which were fed a NaHCO3-supplemented diet. Thus a chloride overload seems to be more important for alteration of adrenergic innervation than the degree of blood pressure elevation or the sodium overload per se.