Altered Protein Kinase C Regulation of Pulmonary Endothelial Store- and Receptor-Operated Ca2+ Entry after Chronic Hypoxia

作者：Paffett Michael L^*; Riddle Melissa A; Kanagy Nancy L; Resta Thomas C; Walker Benjimen R

来源：Journal of Pharmacology and Experimental Therapeutics, 2010, 334(3): 753-760.

DOI：10.1124/jpet.110.165563

Chronic hypoxia (CH)-induced pulmonary hypertension is associated with decreased basal pulmonary artery endothelial cell (EC) Ca2+, which correlates with reduced store-operated Ca2+ (SOC) entry. Protein kinase C (PKC) attenuates SOC entry in ECs. Therefore, we hypothesized that PKC has a greater inhibitory effect on EC SOC and receptor-operated Ca2+ entry after CH. To test this hypothesis, we assessed SOC in the presence or absence of the nonselective PKC inhibitor GF109203X [2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl) maleimide] in freshly isolated, Fura-2-loaded ECs obtained from intrapulmonary arteries of control and CH rats (4 weeks at 0.5 atm). We found that SOC entry and 1-oleoyl-2-acetyl-sn-glycerol (OAG)- and ATP-induced Ca2+ influx were attenuated in ECs from CH rats versus controls, and GF109203X restored SOC and OAG responses to the level of controls. In contrast, nonselective PKC inhibition with GF109203X or the selective PKC epsilon inhibitor myristoylated V1-2 attenuated ATP-induced Ca2+ entry in ECs from control but not CH pulmonary arteries. ATP-induced Ca2+ entry was also attenuated by the T-type voltage-gated Ca2+ channel (VGCC) inhibitor mibefradil in control cells. Consistent with the presence of endothelial T-type VGCC, we observed depolarization-induced Ca2+ influx in control cells that was inhibited by mibefradil. This response was largely absent in ECs from CH arteries. We conclude that CH enhances PKC-dependent inhibition of SOC- and OAG-induced Ca2+ entry. Furthermore, these data suggest that CH may reduce the ATP-dependent Ca2+ entry that is mediated, in part, by PKC epsilon and mibefradil-sensitive Ca2+ channels in control cells.

• 出版日期2010-9