It has been previously suggested that salt loading produces structural changes of the arteries in hypertensive patients who respond to salt loading with a greater rise of blood pressure. This study examined the possibility that salt loading alters venous distensibility in hypertensive patients. Twenty-one patients with essential hypertension were placed on a low-sodium diet (70 meq) for 7 days and then were placed on a high-sodium diet (345 meq) for 7 days. Patients were arbitrarily divided

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... two groups based on the response of their blood pressure to salt loading: (1) those whose mean blood pressure increased by more than 10% while on the high-salt diet as compared with those on the low-salt diet (salt-responsive patients, n = 8) and (2) those whose mean blood pressure did not increase by more than 10% (salt-nonresponsive patients, n = 13). The venous pressure-volume relationship was determined in the forearm with a water-filled plethysmograph when patients were on the lowand high-salt diet. Venous pressure-volume curves were not different between salt-responsive and salt-nonresponsive patients while on the low-salt diet. High-salt intake shifted the curve toward the pressure axis for salt-responsive patients (p < .05) but not for salt-nonresponsive patients. Phentolamine, 1 mg administered intravenously for 5 min, did not significantly alter venous pressure-volume curves for either group while on the lowor high-salt diet. These results suggest that salt loading decreased venous distensibility in salt-responsive patients, which resulted from nonadrenergic mechanisms: structural changes of the veins could perhaps be included as one of these mechanisms.