Elevated endogenous digitalis-like substance in hypertensive diabetic patients with a family history of hypertension.

Endogenous digital-like substance (DLS) is increased in patients with essential hypertension and is hypothesized to play a role in the pathogenesis of high blood pressure. Whether an increase in DLS in diabetic patients with hypertension is associated with a family history of hypertension or diabetic nephropathy was investigated. Plasma DLS was measured as Na(+)-K(+)-ATPase inhibitory activity (ATPI) in 100 Type 2 diabetic patients. Ouabain was used as a standard of Na-K-ATPase inhibition. Diabetic patients with hypertension demonstrated a greater ATPI level than normotensive diabetic patients (p less than 0.05). In patients with hypertension groups, the positive family history group had a higher ATPI level than the negative family history group (p less than 0.01). Microalbuminuria was not correlated with the ATPI level in diabetic patients. These results suggest that ATPI might play a role in the pathogenesis of hereditary hypertension associated with diabetes mellitus, but not have etiologic significance in diabetic nephropathy.