[Sodium-proton exchanges and platelet procoagulant activity in type 1 diabetic patients]

Platelet sodium-proton exchange rate and phospholipid dependent procoagulant activity were measured in 31 type 1 diabetics (mean age 32.3 +/- 10.1 years) and 35 healthy subjects (mean age 35.4 +/- 9.4 years). The activity of platelet Na+/H+ exchanger was measured in platelet rich plasma, using an optical swelling assay, according to Rosskopf et al. Platelet procoagulant activity was measured in platelet rich plasma, platelet poor plasma and platelet/microparticles filtrated plasma, using Russell's viper venom (according to Jy and Horstman) and calibrated with ship L-alpha-phosphatidylethanolamine. We found that Na+/H+ exchange rate was significantly higher in diabetic patients in comparison to the controls (p = 0.0009). There was also a positive correlation between the activity of Na+/H+ exchanger and phospholipid dependent procoagulant activity in all plasma fractions. We did not find a significant association between Na+/H+ exchanger activity and metabolic parameters studied, however in patients with HbA1c level > 7.5% higher Na+/H+ exchange rates were noted. Total procoagulant activity did not rise significantly in diabetic patients, but was markedly higher in platelet poor and platelet filtrated plasma. It was supposed that it originated from platelet derived microparticles, enriched in phospholipids. Our results suggest that an increased platelet Na+/H+ exchange rate and raised procoagulant activity connected with platelet microparticles may enhance the risk of vascular damage in type 1 diabetic patients.