Vascular compliance in sodium-sensitive and sodium-resistant borderline hypertensive patients

Vascular compliance in sodium-sensitive and sodium-resistant borderline hypertensive patients. Recently, we demonstrated a reduction in the compliance of the carotid, femoral and brachial arteries in sodiumsensitive subjects who had consumed a regular sodium intake of approximately 120 mmol per day, as compared to both sodium-resistant borderline hypertensive subjects and normotensive controls. Venous compliance was not different between the two borderline hypertensive groups and was only slightly lesser than in controls. Large artery compliance was studied using a non-invasive ultrasound vessel wall movement detector system, while venous compliance was determined by means of strain gauge plethysmography. The borderline hypertensive subjects were subsequently treated with enalapril 10 mg/day, felodipine 5 mg/day or placebo during six months. Despite similar reductions in blood pressure, enalapril induced a significant increase of the muscular femoral and brachial artery compliance, but not of the elastic carotid artery, while felodipine did not influence large artery compliance at all in the sodium-sensitive group. The effect of enalapril on muscular artery compliance was established through a dose-dependent increase in distension and not through a change in arterial diameter. Arterial compliance was not influenced by either of the drugs in the resistant group. Venous compliance was also not altered by the medication. In conclusion, femoral and brachial artery compliance in sodium-sensitive borderline hypertensive subjects, which was found to be lower than that of sodium-resistant subjects, improved with antihypertensive treatment with enalapril but not with felodipine, despite the similar reductions in blood pressure induced by both drugs. This finding implies that firstly, reduced arterial compliance is caused by more than just blood pressure elevation, and secondly, the renin-angiotensin system may play a role in the reduced arterial compliance of sodium-sensitive subjects