Effect of opening of mitochondrial ATP-sensitive K(+) channels on the expression of hypoxia inducible factor-1alpha and cell proliferation in pulmonary arterial smooth muscle cells of rats.
- Author:
Jian-Ping ZHAO
1
;
Zhi GUO
;
Zhi-Gang ZHOU
;
Jun CHEN
;
Hong-Ling HU
;
Tao WANG
;
Zhen-Xiang ZHANG
Author Information
1. Department of Respiratory Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China. zhaojp@tjh.tjmu.edu.cn
- Publication Type:Journal Article
- MeSH:
Animals;
Cell Hypoxia;
Cell Proliferation;
Cells, Cultured;
Hypoxia-Inducible Factor 1, alpha Subunit;
metabolism;
Male;
Muscle, Smooth, Vascular;
cytology;
physiology;
Myocytes, Smooth Muscle;
cytology;
physiology;
Potassium Channels;
physiology;
Pulmonary Artery;
cytology;
physiology;
Rats;
Rats, Sprague-Dawley
- From:
Acta Physiologica Sinica
2007;59(2):157-162
- CountryChina
- Language:Chinese
-
Abstract:
The objective of this paper was to investigate the effect of mitochondrial ATP-sensitive K(+) (MitoK(ATP)) channels on the expression of hypoxia inducible factor-1alpha (HIF-1alpha) and cell proliferation in pulmonary arterial smooth muscle cells (PASMCs) of rats. Cultured PASMCs were divided into six groups as follows: (1) normoxia group: cultured under normoxia for 24 h; (2) normoxia + diazoxide group: cultured under normoxia with diazoxide, an opener of MitoK(ATP) channel, for 24 h; (3) normoxia + 5-HD group: cultured under normoxia with 5-hydroxydecanoate (5-HD), an antagonist of MitoK(ATP) channel, for 24 h; (4) hypoxia group: cultured under hypoxia (37 degrees C, 5% O(2), 5% CO(2), 90% N(2)) for 24 h; (5) hypoxia + diazoxide group: cultured under hypoxia (37 degrees C, 5% O(2), 5% CO(2), 90% N(2)) with diazoxide for 24 h; (6) hypoxia + 5-HD group: cultured under hypoxia (37 degrees C, 5% O(2), 5% CO(2), 90% N(2)) with 5-HD for 24 h. The relative changes in mitochondrial potential were tested with Rhodamine 123 (R-123) fluorescence technique. Immunohistochemical method was used to trace the expression of HIF-1alpha. The proliferation of PASMCs was examined by MTT colorimetric assay. The results were as follows: The intensity of R-123 fluorescence in normoxia + diazoxide group was significantly increased as compared with that in normoxia group (P<0.05), and the intensity of R-123 fluorescence in hypoxia + diazoxide group was also significantly increased as compared with that in hypoxia group (P<0.05). 24-hour hypoxia or 24-hour hypoxia + diazoxide markedly increased the intensity of R-123 fluorescence in PASMCs as compared with normoxia (P<0.05), and the change was more prominant in hypoxia + diazoxide group than that in hypoxia group (P<0.05). There was no significant difference in the intensity of R-123 fluorescence between normoxia group and normoxia + 5-HD group (P>0.05). However, 5-HD weakened the effect of 24-hour hypoxia on the intensity of R-123 fluorescence. The intensity of R-123 fluorescence in hypoxia + 5-HD group was significantly decreased as compared with that in hypoxia group (P<0.05). After exposure to hypoxia or hypoxia + diazoxide for 24 h, the expression of HIF-1alpha and the proliferation of PASMCs were significantly increased as compared with that in normoxia or normoxia + diazoxide group (P<0.05), and the change was more significant in hypoxia + diazoxide group than that in hypoxia group (P<0.05). There was no significant difference in the expression of HIF-1alpha and the proliferation of PASMCs between normoxia group and normoxia + 5-HD group (P>0.05). However, the expression of HIF-1alpha and the proliferation of PASMCs in hypoxia + 5-HD group were significantly decreased as compared with that in hypoxia group (P<0.05). All these results suggest that the opening of MitoK(ATP) channels followed by a depolarization of mitochondrial membrane might contribute to the increase of the expression of HIF-1alpha and the proliferation of PASMCs. This might be a mechanism of the development of hypoxic pulmonary hypertension.
