ACTIVITIES OF AMINOPEPTIDASES IN A RAT SALINE MODEL OF VOLUME HYPERTENSION

Aminopeptidase activity plays a role in the metabolism of several pept ides that could be involved in blood pressure control. This activity h as been implicated in the pathogenesis of hypertension, essentially in spontaneously hypertensive rats. However, few studies have examined a minopeptidase activities in animal models other than genetic hypertens ion. To analyze the aminopeptidase response to the specific conditions of the reduced renal mass saline model of arterial hypertension, amin opeptidase A activity (glutamyl-and aspartyl-aminopeptidase), aminopep tidase M activity (alanyl-aminopeptidase), aminopeptidase B activity ( arginyl-aminopeptidase), pyroglutamyl-aminopeptidase and cystinyl-amin opeptidase were measured in the neurohypophysis, in the adrenal gland and in serum of this model of hypertension. In the neurohypophysis, th ere was a significant increase of soluble cystinyl-, alanyl-, arginyl- , pyroglutamyl- and membrane-bound aspartyl-aminopeptidase activities in hypertensive animals. In the adrenal gland, soluble cystinyl-, alan yl-, arginyl-and pyroglutamyl-aminopeptidase activities were also high er in hypertensive rats than in normotensive controls. No differences were found in serum levels of aminopeptidase activities between both g roups of animals. A highly significant positive correlation between th e neurohypophysis and the adrenal gland was observed for soluble cysti nyl- and alanyl-aminopeptidase activities in the model of hypertension , whereas no correlation was observed in normotensive rats. Our result s suggest that aminopeptidase activities could be involved in the regu latory response to the reduced renal mass hypertension and also sugges t a coordinate response between the adrenal gland and the neurohypophy sis, to the specific metabolic conditions of this model of hypertensio n.