Aminopeptidase activity plays a role in the metabolism of several
peptides that could be involved in blood pressure control. This activity has been implicated in the pathogenesis of
hypertension, essentially in spontaneously hypertensive rats. However, few studies have examined
aminopeptidase activities in animal models other than genetic
hypertension. To analyze the
aminopeptidase response to the specific conditions of the reduced renal mass saline model of arterial
hypertension,
aminopeptidase A activity (glutamyl- and
aspartyl-aminopeptidase),
aminopeptidase M activity (
alanyl-aminopeptidase),
aminopeptidase B activity (
arginyl-aminopeptidase), pyroglutamyl-
aminopeptidase and
cystinyl-aminopeptidase were measured in the neurohypophysis, in the adrenal gland and in serum of this model of
hypertension. In the neurohypophysis, there 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-, alanyl-, arginyl- and pyroglutamyl-
aminopeptidase activities were also higher in hypertensive rats than in normotensive controls. No differences were found in serum levels of
aminopeptidase activities between both groups of animals. A highly significant positive correlation between the neurohypophysis and the adrenal gland was observed for soluble cystinyl- and
alanyl-aminopeptidase activities in the model of
hypertension, whereas no correlation was observed in normotensive rats. Our results suggest that
aminopeptidase activities could be involved in the regulatory response to the reduced renal mass
hypertension and also suggest a coordinate response between the adrenal gland and the neurohypophysis, to the specific metabolic conditions of this model of
hypertension.