title: The functional significance of the rho/rho-kinase pathway in human erythrocytes.
abstract: OBJECTIVE
  Erythrocyte deformability, which can be influenced by various intracellular signaling mechanisms, such as nitric oxide, cAMP, cGMP, and protein kinases, is the most important physiological factor providing the blood flow in microcirculation. However, the functional significance of the Rho/Rho-kinase pathway, which contributes cell shape changes and the reorganization of the actin cytoskeleton, has yet to be explored in erythrocytes. Therefore, we examined the influence of several activators and inhibitors of Rho/Rho-kinase signaling on human erythrocyte deformability.
  
  
  METHODS
  RhoA and ROCK-2 proteins were studied by western blotting. Influences of 2 Rho-kinase inhibitors, fasudil and Y-27632 (both 10-7 to 10-4 M), on erythrocyte deformability was determined by ektacytometer at various shear stresses (0-30 Pa) in the presence or absence of a known Rho activator, lysophosphatidic acid (LPA, 10-5 to 5x10-5 M, 1-15 min).
  
  
  RESULTS
  LPA incubation reduced deformability with concomitant RhoA-GTP inhibition. Y-27632 and fasudil also decreased deformability, but had no effect on LPA-induced reduction of deformability. Rho inhibitor C3 had no effect on RhoA activation. Reduction in RhoA activation was induced by sub-hemolytic mechanical stress.
  
  
  CONCLUSIONS
  Our findings may indicate that the Rho/Rho-kinase pathway could contribute to the regulation of deformability of human erythrocytes.
authors.affiliation: Mersin University Faculty of Medicine, Department of Pharmacology, Mersin, Turkey.
authors.forename: R Nalan
authors.initials: RN
authors.lastname: Tiftik
authors.affiliation: Koç University Faculty of Medicine, İstanbul, Turkey.
authors.forename: Oğuz K
authors.initials: OK
authors.lastname: Başkurt
authors.affiliation: Gaziantep University Faculty of Medicine, Department of Biostatistics, Gaziantep, Turkey.
authors.forename: Seval
authors.initials: S
authors.lastname: Kul
authors.affiliation: Mersin University Faculty of Medicine, Department of Pharmacology, Mersin, Turkey.
authors.forename: Kansu
authors.initials: K
authors.lastname: Büyükafşar
keywords: C3; Erythrocyte deformability; Fasudil; Lysophosphatidic acid; Rho-kinase; RhoA; Y-27632