Disappearance of Hypoxic Pulmonary Vasoconstriction and O2-Sensitive Nonselective Cationic Current in Arterial Myocytes of Rats Under Ambient Hypoxia.
10.4196/kjpp.2013.17.5.463
- Author:
Hae Young YOO
1
;
Sung Joon KIM
Author Information
1. Department of Physiology and Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul 110-799, Korea. sjoonkim@snu.ac.kr
- Publication Type:Original Article
- Keywords:
Chronic hypoxia;
Hypoxic pulmonary vasoconstriction;
Nonselective cation channel;
O2-sensitive ion channel;
Pulmonary artery
- MeSH:
4-Aminopyridine;
Animals;
Anoxia*;
Lung;
Muscle Cells*;
Myocytes, Smooth Muscle;
Pulmonary Artery;
Rats*;
Thromboxane A2;
Vasoconstriction*
- From:The Korean Journal of Physiology and Pharmacology
2013;17(5):463-468
- CountryRepublic of Korea
- Language:English
-
Abstract:
Acute hypoxia induces contraction of pulmonary artery (PA) to protect ventilation/perfusion mismatch in lungs. As for the cellular mechanism of hypoxic pulmonary vasoconstriction (HPV), hypoxic inhibition of voltage-gated K+ channel (Kv) in PA smooth muscle cell (PASMC) has been suggested. In addition, our recent study showed that thromboxane A2 (TXA2) and hypoxia-activated nonselective cation channel (I(NSC)) is also essential for HPV. However, it is not well understood whether HPV is maintained in the animals exposed to ambient hypoxia for two days (2d-H). Specifically, the associated electrophysiological changes in PASMCs have not been studied. Here we investigate the effects of 2d-H on HPV in isolated ventilated/perfused lungs (V/P lungs) from rats. HPV was almost abolished without structural remodeling of PA in 2d-H rats, and the lost HPV was not recovered by Kv inhibitor, 4-aminopyridine. Patch clamp study showed that the hypoxic inhibition of Kv current in PASMC was similar between 2d-H and control. In contrast, hypoxia and TXA2-activated I(NSC) was not observed in PASMCs of 2d-H. From above results, it is suggested that the decreased I(NSC) might be the primary functional cause of HPV disappearance in the relatively early period (2 d) of hypoxia.
