Effects of High Salt Intake on Hemodynamic Responses to Isometric Exercise in Normotensive Subjects and in Patients with Essential Hypertension : The 12th Conference on the Pathogenesis of Hypertension

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Hemodynamic responses to isometric were compared between 9 normotensive subjects (NT) and 16 patients with essential hypertension (EH) before and during high salt intake. The subjects were hospitalized and placed on a diet containing 6 g of salt per day. Baseline hemodynamic studies were carried out on supine subjects before and 3 min after isometric exercise (30% of the maximal voluntary handgrip). Plasma concentration of norepinephrine (PNE) was also measured. Brachial arterial pressure was directly recorded and cardiac output (CO) was measured by the dye-dilution technique using a cuvette. The hemodynamic studies were repeated on the 5th day of a high salt diet (16 g of salt per day). Retention of sodium was calculated on a daily basis by measuring the actual intake of sodium and 24-hour urinary excretion of sodium. Pressor responses to isometric exercise were significantly greater in the EH than in the NT group. Patterns of hemodynamic responses were different in the 2 groups, i.e., the elevation of arterial pressure was maintained by an increase in CO in the NTs, while it was maintained by increases in CO and total peripheral vascular resistance (TPR) in the EHs. The increase in CO was significantly greater in the NT than in the EH group [15 ± 3 (mean ± SE) vs 7 ± 1%, p < 0.05]. Although the salt loading reduced heart rate similarly in both groups (-9.0 ± 2.1, p < 0.01, in the NTs and -11.9 ± 2.9%, p < 0.01, in the EHs), the high salt diet did not significantly alter mean arterial pressure (MAP), CO or TPR in either group. The high salt diet, however, exaggerated the arterial pressure elevation and the increase in TPR induced by isometric induced increases of PNE in either group. The degree of sodium retention was comparable in the 2 groups. Thus, it is suggested that the increased pressor response to isometric exercise in the EHs is attributable to the enhanced sensitivity of the resistance vessels to sympathetic stimulation, and that the resistance vessels of the EHs which are sensitive to even small increases of sodium intake may exert an influence of cardiovascular function in essential hypertension.
社団法人日本循環器学会の論文
1983-10-20

Effects of High Salt Intake on Hemodynamic Responses to Isometric Exercise in Normotensive Subjects and in Patients with Essential Hypertension : The 12th Conference on the Pathogenesis of Hypertension

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