MODULATION DEFECT OF SODIUM-PUMP EVIDENCED IN DIABETIC-PATIENTS BY A MICROCALORIMETRIC STUDY

Sodium pump activity of intact erythrocytes in their own plasma was me asured by microcalorimetry in 41 healthy subjects and 35 insulin-depen dent diabetic patients. Results show that modulation of the sodium pum p is altered in diabetic patients. Addition of insulin increases funct ioning of the Na+-K+ pump in controls but has no effect in diabetic pa tients. These subjects show a slower response of the Na+-K(+)pump to t he inhibitory effect of ouabain. Cross-incubation experiments suggest that these findings may be explained by the existence of a plasmatic f actor that impairs the modulation of the sodium pump in diabetic patie nts.