title: The effect of human proinsulin C-peptide on erythrocyte deformability in patients with Type I diabetes mellitus.
abstract: OBJECTIVE
  In recent years, evidence has arisen that proinsulin C-peptide exerts biological effects especially on microcirculation, e.g. C-peptide has been shown to increase skin microcirculation in patients with Type I (insulin-dependent) diabetes mellitus and to activate endothelial nitric oxide synthase. This study aimed to investigate the influence of pro-insulin C-peptide on erythrocyte deformability which was assessed by means of laser diffractoscopy.
  
  
  METHODS
  Blood samples from healthy control subjects (n = 10) and Type I diabetic patients (n = 15) completely deficient of C-peptide were analysed at shear stresses ranging from 0.3 to 30 Pa.
  
  
  RESULTS
  Erythrocyte deformability was lower in the group of Type I diabetic patients than in the control subjects. Preincubation of the diabetic blood samples with various concentrations of human proinsulin C-peptide for 8 h restored the deformability of erythrocytes, almost reaching the values of control samples. In contrast, proinsulin C-peptide did not modify the erythrocyte deformability of control subjects.
  
  
  CONCLUSIONS
  We conclude that proinsulin C-peptide is able to ameliorate the impaired deformability of erythrocytes in Type I diabetic patients and we hypothesise that this effect is mediated by restoration of Na(+)-K(+)-ATPase activity, which is known to be attenuated in diabetic patients.
authors.affiliation: Department of Endocrinology, University of Mainz, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kunt
authors.forename: S
authors.initials: S
authors.lastname: Schneider
authors.forename: A
authors.initials: A
authors.lastname: Pfützner
authors.forename: K
authors.initials: K
authors.lastname: Goitum
authors.forename: M
authors.initials: M
authors.lastname: Engelbach
authors.forename: B
authors.initials: B
authors.lastname: Schauf
authors.forename: J
authors.initials: J
authors.lastname: Beyer
authors.forename: T
authors.initials: T
authors.lastname: Forst
mesh_terms: D002096:C-Peptide / Q000494:pharmacology*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004907:Erythrocyte Deformability / Q000187:drug effects*; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D007834:Lasers; D010042:Ouabain / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
chemical_list: D002096:C-Peptide; D004791:Enzyme Inhibitors; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase