The skeletal muscle Na:K ratio is not increased in hypertension: evidence for the importance of obesity and glucose intolerance.

Several previous studies have suggested that hypertension is associated with altered sodium transport across the cell membrane. The aim of the present study was to study the skeletal muscle Na:K ratio in relation to blood pressure and glucose tolerance in obese and non-obese men. Muscle biopsies were taken from the femoral vastus lateralis muscle in men aged 52 +/- 5 years and the electrolytes were analyzed. Ten obese men with impaired glucose tolerance and hypertension, 10 obese normotensive controls, 10 lean men with hypertension and 10 lean normotensive controls participated in the study. Higher insulin levels were found in both hypertensive groups compared with the respective normotensive groups. Increased muscle Na:K ratio was found in obesity (P less than 0.01) and this was further enhanced when combined with hypertension and impaired glucose tolerance (P less than 0.001). However, hypertension in lean individuals was not associated with an increased muscle Na:K ratio. These data suggest that the increased muscle Na:K ratio in obese subjects and those with impaired glucose tolerance is not solely due to insulin resistance and hyperinsulinemia. Furthermore, the data clearly suggest that there is no important general perturbation of the Na-K pump in hypertension per se.