Impairment of renal vasodilation with L-arginine is related to more severedisease in untreated hypertensive patients

Data remain insufficient to place the decreased response to L-arginine in h ypertensive patients within a consistent pathophysiological sequence. The a im of the present study in patients with essential hypertension was to asse ss the relationships between the response to L-arginine and a set of releva nt clinical and laboratory parameters. In this prospective, interventional study, we administered L-arginine to untreated hypertensive individuals and healthy control subjects and measured the clearance of inulin and of para- aminohippurate and a set of biochemical and clinical variables. L-Arginine infusion revealed major differences between control subjects and 1 subgroup (group B) of hypertensive individuals. Group B hypertensives (n = 18) had no increase in inulin clearance and no decrease in renal vascular resistanc e with L-arginine; however, in another subset of hypertensive patients (gro up A, n = 27), the insulin clearance increased and renal vascular resistanc e decreased similar to the control group (group C, n = 11). The ambulatory blood pressure monitoring in group B showed both an increased mean diastoli c pressure and a "nondipper" pattern in the nocturnal regulation of arteria l pressure. These findings in group B were accompanied by significant alter ations in optic fundus and left ventricle hypertrophy and increased microal buminuria (all, P<0.05). Furthermore, group B individuals had significantly lower values of HDL cholesterol and a higher baseline atherogenic index, p lasma insulin level, and glucose/insulin index. We disclose a previously un described relationship between end organ repercussion and decreased renal h emodynamic response to L-arginine. Our results may help to understand the m echanisms that lead to target organ damage in hypertension.