Increased cytosolic free sodium concentrations in platelets from type 2 (non-insulin-dependent) diabetic patients is...

Cytosolic free sodium concentrations ([Na+]i) in intact platelets from 32 type 2 (non-insulin-dependent) diabetic patients and from 27 age- and sex-matched non-diabetic control subjects were measured with the novel sodium-sensitive fluorescent dye sodium-binding-benzofuran-isophthalate. [Na+]i was significantly higher in platelets from type 2 diabetic patients compared with control subjects (40.6 +/- 2.4 vs 32.0 +/- 2.0 mmol/l, means +/- S.E.M., P < 0.03). Both systolic and diastolic blood pressure were significantly elevated in diabetic patients compared with control subjects. Analysis of diabetic patients showed a significant association between [Na+]i and diastolic blood pressure (P = 0.026). Stimulation of Na/H exchange by thrombin increased [Na+]i in both groups. After inhibition of Na/K/ATPase by ouabain (1 mmol/l), [Na+]i was significantly increased both in diabetic patients and non-diabetic subjects in a similar way (by 40.2 +/- 7.3 and 31.7 +/- 5.3 mmol/l respectively). It is concluded that increased [Na+]i in cells from type 2 diabetic patients may be related to hypertension.