Abnobmal Saphenous Vein Composition in Human Hypertension

Abstract

The water, sodium, potassium, glycosaminoglycan (hexosamine), and bound sodium content of saphenous veins obtained from 90 male patients undergoing coronary artery or renal artery bypass surgery was measured. For measurement of bound sodium content, the veins were frozen and thawed twice (to disrupt cell membranes) then incubated in physiologic salt solution at 37°C for one hour. Bound sodium was calculated by subtraction of dissolved sodium from total sodium. Based on chart review, the patients were classified as normotensive (N=43, aged 56.1 years, mean), hypertensive (N=35, aged 55.6) and borderline hypertensive (N=12, aged 58.3). Seventy-seven percent of hypertensive, 17 percent of borderline hypertensive and 2 percent of normotensive patients were receiving thiazide diuretics prior to surgery. Saphenous vein water, 734 ± 3 ml/kg wet weight (mean ± SE), and hexosamine, 34.1 ± 1.2 mM/kg dry weight (N = 14), content of hypertensive patients was increased (p < 0.05) compared to values obtained in normotensives (724 ± 3 and 30.7 ± 1.0, N = 20). Venous wall hexosamine and bound sodium contents were positively correlated in the normotensive (r = 0.89, p < 0.01, N = 10) but not in the hypertensive group of patients (r = 0.35, N = 9). The water content of veins of patients with borderline hypertension was 740 ± 11 ml/kg wet weight (N=11, p < 0.06). The extensive use of diuretics might have accounted for the lack of differences in the electrolyte and bound sodium content of veins among the groups. The findings indicate that vascular wall waterlogging may occur on both the high- and low-pressure side of the circulation in human hypertension; therefore, circulating humoral factors also may participate in its pathogenesis. The increased hexosamine concentration of veins in human hypertension may be a manifestation of systemic atherosclerosis rather than of hypertension.