Salt and experimental hypertension: the influence of age

In a series of experiments, age-dependent differences in the development of DOCA-saline hypertension (HPT) were studied in the rat. Immature animals developed--in contrast to the adult ones--a more severe and self-sustaining HPT, associated with a more pronounced retention of fluid and a greater increase of renal collagen which was preceded by a more rapid decrease in renal renin content. It is suggested that changes in intrarenal haemodynamics due to the suppression of renal renin-angiotensin system play a role in the pathogenesis of hypertensive renal lesions which develop more readily in immature animals and are responsible for their more severe HPT. Similarly, monkeys exposed to increased salt intake from earliest stages of postnatal ontogeny are also more prone to develop salt hypertension more rapidly than the adult ones. The increased salt intake before sexual maturity may thus be considered as a risk factor for the development of hypertension also in man.