gms | German Medical Science

Background: Both ageing and essential hypertension are implicated in deterioration of endothelium dependent vasodilation in the forearm vasculature. Whether this is also the case in the renal vascular bed has not yet been determined.

Methods: The decrease in renal plasma flow in response to systemic inhibition of NO synthase by L-NMMA (4.25mg/kg), reflecting basal nitric oxide (NO) activity, was assessed in 73 hypertensive patients and 43 normotensive control subjects. To determine the role of ageing for basal NO activity, both groups were divided into two groups according to age (< or > 40 years).

Results: The decrease in RPF in response to L-NMMA correlated significantly with age in the whole study population (r=0.29; p=0.02). Separate analysis revealed that in normotensive control subjects this correlation was more pronounced (r=0.38; p=0.01), whereas only a trend towards a relation was evident in the hypertensive group (r=0.22; p=0.06). The decrease in RPF in response to L-NMMA was -16.3±10.0% in young normotensives (29.2±3.9 years), -10.6±7.2% in old normotensives (52.3±6.2 years), -11.5±13.6 in young hypertensives (30.9±5.3 years), and -8.6±9.4% in old hypertensives (53.7±6.4 years). In young normotensive control subjects, the decrease in RPF was significantly greater than in old normotensive control subjects and old hypertensive patients (p=0.04 and p=0.002, respectively), and tended to be more pronounced than in young hypertensive patients (p=0.09). In contrast to the normotensive control group, the decrease in RPF did not differ between young and old patients in the hypertensive group (p=0.29).

Conclusions: Alterations of renal endothelial function that occur in essential hypertension appear to represent an accelerated form of the deterioration of basal NO activity that is associated with ageing.