C‐peptide and insulin at physiological ratios rescue low O 2 ‐induced ATP release from erythrocytes (RBCs) of humans with type 2 diabetes: implications for the prevention of microvascular complications (1108.4)

RBCs participate in the matching of O₂ delivery with tissue need via release of O₂ and ATP when these cells are exposed to low pO₂. This response is deficient in DM2 RBCs. We reported that incubation of healthy human (HH) RBCs with insulin at postprandial levels inhibits low O₂‐induced ATP release. However, in vivo, insulin is co‐released with equimolar amounts of C‐peptide, but due to different degradation rates, C‐peptide levels exceed those of insulin. We reported that co‐incubation of these peptides, at physiological ratios and concentrations, prevents the adverse effects of insulin on ATP release from HH RBCs. Here we extend these studies to DM2 RBCs. Using Western analysis, we found that the C‐peptide receptor, GPR146, is present on both HH (n=2) and DM2 (n=5) RBCs and pre‐incubation of HH RBCs with an antibody to an external epitope of GPR146 inhibited C‐peptide‐mediated effects (n=3). We next determined that co‐incubation of DM2 RBCs with C‐peptide and insulin at physiological ratios of 1:1 (n=6) or 4:1 (n=8) restored low O₂‐induced ATP release. We also investigated if C‐peptide acts via stimulation of soluble guanylyl cyclase (sGC) activity. The selective sGC inhibitor, ODQ, prevented C‐peptide rescue of low O₂‐induced ATP release in DM2 RBCs. These data suggest a heretofore unrecognized synergism between C‐peptide and insulin that could be important for prevention of the microvascular complications of DM2. Grant Funding Source : Supported by ADA, AHA and NIH