IMPAIRMENT OF ENDOTHELIAL FUNCTION IN SALT-SENSITIVE HYPERTENSION IN HUMANS

In this study, we evaluated the relationship between the endothelium-d ependent vasodilation and salt sensitivity in patients with essential hypertension. Fifteen untreated hypertensive male patients (age, 29 to 54 years) were sodium restricted (5 g/day) for 1 week, and placed on a high salt diet (20 g/day) the second week. At the end of each period , measurements of forearm vascular responses to drugs (acetylcholine, 3 to 24 mu g/min; sodium nitroprusside, 0.15 to 1.2 mu g/min; norepine phrine, 0.15 to 1.2 mu g/min; and N-G-monomethyl-L-arginine [L-NMMA], 1 to 8 mu mol/min) were obtained by using strain-gauge venous plethysm ography. Subjects were divided into two groups according to the blood pressure response to sodium loading: salt-sensitive hypertensive group (24-h mean increase of arterial pressure greater than or equal to 10% ; n = 6) and salt-resistant group (< 10%; n = 9). The two groups showe d no significant difference in clinical data or mean arterial pressure during low salt intake. The dose-dependent vasodilation induced by ac etylcholine was significantly reduced (P < .05) in the salt-sensitive hypertensive patients v the salt-resistant patients regardless of sodi um loading. There were no differences between the two groups in respon se to sodium nitroprusside, norepinephrine, or L-NMMA. These results i ndicate that vasodilation to acetylcholine is reduced in salt-sensitiv e hypertensive patients even on restricted sodium diets. This may cont ribute to blood pressure elevation when sodium intake is increased. (C ) 1997 American Journal of Hypertension, Ltd.