Transmembrane cationic fluxes in erythrocytes of diabetics and normal men.

The relationship between erythrocyte cation transport systems, membrane and plasma lipids, plasma prorenin and microalbuminuria was examined in normal men and patients with insulin dependent diabetes mellitus (IDDM). Different measurements of erythrocyte transport systems were obtained in patients with IDDM and in age- and weight-matched healthy men: Na+/Li(+)-countertransport activity, Na+/K(+)-cotransport activity, Na+/K(+)-ATPase pump activity and the ground membrane permeability for Na+ and K+ as well as the intraerythrocyte Na+, K+ and Mg2+ concentration. Plasma prorenin, cholesterol, triglycerides, phospholipids, low and high density lipoprotein cholesterol and erythrocyte membrane cholesterol and phospholipids content were also obtained from the fasting subjects. The patients with IDDM had an elevated (p < 0.05 or less) erythrocyte Na+/Li(+)-countertransport activity, ground membrane leak for K+, intraerythrocyte K+ concentration, erythrocyte membrane cholesterol content, but a lower red blood cell phospholipids content. In single regression analysis the erythrocyte Na+/Li(+)-countertransport, Na+/K(+)-cotransport and Na+/K(+)-ATPase pump activity and ground membrane leak for Na+ and K+ were inversely related to the red cell membrane lipid content. The erythrocyte Na+/Li(+)-countertransport activity and K+ leak were also positively related to the plasma prorenin level and urinary microalbumin excretion. Our data in patients with IDDM show that an elevated erythrocyte membrane lipid content was accompanied by a lower erythrocyte Na+/Li(+)-countertransport, Na+/K(+)-cotransport or Na+/K(+)-ATPase pump activity. The elevated Na+/Li(+)-countertransport activity was also accompanied by a higher plasma prorenin level and microalbuminuria.