VASCULAR DISTENSIBILITY AND COMPLIANCE IN SALT-SENSITIVE AND SALT-RESISTANT BORDERLINE HYPERTENSION

Objective: To gain insight into the relationship between vascular comp liance and sodium sensitivity. Design: Arterial and venous compliance was determined in 17 sodium-sensitive and 28 sodium-resistant, young, borderline hypertensive males and in 10 age-matched normotensive contr ols, during regular sodium intake. Methods: The carotid, femoral and b rachial arteries were studied using a non-invasive ultrasound vessel w all movement detector system, and venous compliance was determined usi ng forearm strain-gauge plethysmography. Cardiac output, plasma volume and hormonal factors, such as plasma renin activity, were also measur ed to assess their possible influence on vascular compliance. Results: Large artery compliance was significantly less in the sodium-sensitiv e than in the sodium-resistant subjects in all arteries studied. Compa red with controls, arterial compliance was reduced significantly in th e sodium-sensitive group, whereas the sodium-resistant group did not d iffer significantly from the controls. Venous compliance was reduced e qually in the two hypertensive groups compared with the controls, alth ough the differences did not reach statistical significance. Cardiac o utput, blood pressure, plasma volume and hormonal factors did not diff er between sodium-sensitive and sodium-resistant subjects and could no t have been responsible for the observed differences in arterial compl iance. Conclusions: The results of this study suggest that sodium-sens itive borderline hypertensives have reduced large artery compliance co mpared with age-matched sodium-resistant subjects. Since this finding could not be explained by differences in haemodynamic or hormonal fact ors between the groups, this suggests alterations to the viscoelastic properties of the arterial walls in sodium-sensitive subjects.