title: Endothelin-1 improves the impaired filterability of red blood cells through the activation of protein kinase C.
abstract: We previously showed that the deformability of human red blood cells (RBCs) is affected by intracellular signaling pathways by examining the effects of Ca2+ influx and the intracellular cAMP level on mechanically-impaired RBC filterability. In the present study, we investigated whether protein kinase C (PKC) participates in the regulation of RBC deformability by affecting membrane properties. The filterability of mechanically-stressed RBCs showed a V-shaped curve depending on the extracellular Ca2+ concentration; the maximum decrease was achieved at 20-40 microM. The PKC activity, as measured in the membrane-rich fraction by an ELISA method using an antibody for the phosphorylated PKC substrate, maximally increased at the extracellular Ca2+ concentration where the filterability showed a marked improvement following the bottom of the V-shaped curve of the impaired filterability. At this Ca2+ concentration, the PKC activator endothelin-1 increased the PKC activity, and a PKC inhibitor (calphostin C) decreased it. Endothelin-1 improved and calphostin C worsened the impaired filterability. A specific type-B endothelin receptor agonist (IRL 1620) also improved the impaired filterability. A Western blot analysis revealed the presence of endothelin receptors in the RBC membrane. These results indicate that PKC improves the impaired filterability and that RBCs are the target of endothelin-1.
authors.affiliation: NTT Medical Research Institute, Kanto Teishin Hospital, Tokyo, 141-0022, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sakashita
authors.forename: T
authors.initials: T
authors.lastname: Oonishi
authors.forename: N
authors.initials: N
authors.lastname: Ishioka
authors.forename: N
authors.initials: N
authors.lastname: Uyesaka
mesh_terms: D015153:Blotting, Western; D002118:Calcium / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation; D004907:Erythrocyte Deformability / Q000187:drug effects*; D004912:Erythrocytes / Q000166:cytology / Q000502:physiology; D006801:Humans; D011493:Protein Kinase C / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D019332:Endothelin-1; D011493:Protein Kinase C; D002118:Calcium