OBJECTIVETo observe the role of PKC-potentiated inhibitory protein for protein phosphatase 1 of 17 x 10(3) (CPI-17) in vascular calcium sensitivity regulated by protein kinase Calpha (PKCalpha) and Cepsilon (PKCepsilon) in rats with hemorrhagic shock (HS).

METHODSEight Wistar rats were used to reproduce 2 h HS model. Superior mesenteric artery (SMA) rings from HS rats were randomly divided into 2 h shock group (without treatment), PKCalpha agonist group (with addition of thymelea toxin into the nutrient solution), CPI-17 antibody + PKCalpha agonist group [incubation with thymelea toxin and CPI-17 antibody (1:800)], PKCepsilon agonist group (with addition of carbachol into the nutrient solution), and CPI-17 antibody + PKCepsilon agonist group [incubation with carbachol and CPI-17 antibody (1:800)]. SMA rings from another eight normal rats were used as normal control group. Calcium sensitivity indices (Emax, pD2) of SMA rings were measured by isolated organ perfusion system. Hypoxic VSMCs in primary culture were randomly divided into 2 h hypoxia group, PKCalpha agonist group (with above-mentioned treatment), PKCepsilon agonist group (with above-mentioned treatment), normal VSMCs were used as normal control group. Protein expression and phosphorylation of CPI-17 were measured via Western blot.

RESULTSEmax and pD2 in all the experimental groups were lower than those in normal control group (P < 0.01). Emax in PKCalpha agonist group and PKCepsilon agonist group was increased (5.8 +/- 0.8, 5.8 +/- 0.9 mN, respectively) as compared with that of 2 h shock group (4.1 +/- 0.6 mN, P < 0.01). Protein expression and phosphorylation of CPI-17 in VSMC were significantly decreased in 2 h hypoxia group, compared with those in normal control group (P < 0.05), and those in PKCalpha agonist and PKC agonist groups (P < 0.05 or P < 0.01).

CONCLUSIONSPKCalpha and PKCepsilon may regulate vascular calcium sensitivity through change in protein expression and activity of CPI-17 in HS rats.