Background: Evidence indicates that protein kinase C (PKC) plays a pivotal role in hypoxia-induced pulmonary hypertension (PH), but PKC isoform-specific protein expression in pulmonary arteries and their involvement in hypoxia-induced PH are unclear.
Material/Methods: Male SD rats (200–250 g) were exposed to normobaric hypoxia (10% oxygen) for 1, 3, 7, 14 and 21 d (days) to induce PH. PKC isoform-specific membrane translocation and protein expression in pulmonary arteries were determined by using Western blot and immunostaining.
Results: We found that only 6 isoforms of conventional PKC (cPKC) α, βI and βII, and novel PKC (nPKC) δ, ε and η were detected in pulmonary arteries of rats by Western blot. Hypoxic exposure (1–21 d) could induce rat PH with right ventricle (RV) hypertrophy and vascular remodeling. The cPKCβII membrane translocation at 3–7 d and protein levels of cPKCα at 3-14 d, βI and βII at 1-21 d decreased, while the nPKCδ membrane translocation at 3–21 d and protein levels at 3–14 d after hypoxic exposure in pulmonary arteries increased significantly when compared with that of the normoxia control group (p<0.05 vs. 0 d, n=6 per group). In addition, the down-regulation of cPKCα, βI and βII, and up-regulation of nPKCδ protein expressions at 14 d after hypoxia were further confirmed by immunostaining.
Conclusions: This study is the first systematic analysis of PKC isoform-specific membrane translocation and protein expression in pulmonary arteries, suggesting that the changes in membrane translocation and protein expression of cPKCα, βI, βII and nPKCδ are involved in the development of hypoxia-induced rat PH.

Keywords: Isoenzymes - metabolism, Hypertension, Pulmonary - etiology, Chronic Disease, Blotting, Western, Anoxia - complications, Protein Kinase C - metabolism, Pulmonary Artery - enzymology