Distribution of κ-opioid receptor in the pulmonary artery and its changes during hypoxia

Abstract

The present study evaluated the distribution of κ-opioid receptors (κ-ORs) in pulmonary arteries (PAs) in rats and investigated whether κ-ORs are altered in PAs during hypoxia. An animal model of hypobaric/hypoxic pulmonary hypertension and a pulmonary artery smooth muscle cell (PASMC) model of hypoxia were utilized. Distribution of κ-ORs was determined by fluorescence immunohistochemistry and changes in κ-ORs expression in PAs and PASMCs were determined by fluorescence immunohistochemistry or Western blot techniques. The κ-ORs were primarily distributed in the smooth muscle layer of the PAs and in the nucleus of PASMCs. The expression of the κ-ORs were increased in PAs of rats subjected to hypoxia for 1-4 week (P < 0.01). Accordingly, the expression of κ-ORs in PASMCs were also increased when subjected to hypoxia for 12-36 hr (P < 0.05). The present study has provided evidence for the first time of the precise location of κ-ORs in PAs and PASMCs of rats and that hypoxia upregulates expression of κ-ORs. © 2009 Wiley-Liss, Inc.