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TRPV4 channel mediates the increase of pulmonary microvascular endothelial permeability in rats with chronic hypoxic pulmonary hypertension

JIAO Hai-Xia^1,2, YUAN Sheng-Xia^2,3, HUANG Yan-Zhen², SU Qiao-Wen^2,4, HE Rui-Lan^1,2, WU Zhi-Juan^1,2, LIN Mo-Jun^1,2,*

¹School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350122, China；²The Key Laboratory of Fujian Province Universities on Ion Channel and Signal Transduction in Cardiovascular Diseases, Fujian Medical University, Fuzhou 350122, China；³The 900th Hospital of Joint Logistic Support Force, PLA, Fuzhou 350102, China；⁴Department of Pathology, Affiliated Quanzhou First Hospital of Fujian Medical University, Quanzhou 362000, China

Abstract

The purpose of the present study was to investigate the effect of transient receptor potential vanilloid 4 (TRPV4) channel on the permeability of pulmonary microvascular endothelial cells (PMVECs) in rats with chronic hypoxia-induced pulmonary hypertension (CHPH), so as to clarify the mechanism of vascular endothelial dysfunction during the occurrence of pulmonary hypertension (PH). CHPH rat model was established by exposure to chronic hypoxia (CH) for 21 days. Primary PMVECs were cultured by adherent tissue blocks at the edge of the lung. The permeability coefficient of primary cultured PMVECs was detected by fluorescein isothiocyanate (FITC)-dextran. The structure of tight junction (TJ) was observed by transmission electron microscope. The expression of TRPV4 and TJ-related proteins, such as, Occludin, Claudin-5, ZO-1 were examined by real-time fluorescence quantitative PCR and Western blotting. The intracellular calcium concentration ([Ca2+]i) in PMVECs and its effect on PMVECs permeability were observed after the intervention of TRPV4 specific agonist GSK1016790A (GSK, 10 nmol/L) and specific inhibitor HC-067047 (HC, 1 μmol/L, 0.5 μmol/L). The results showed that the CHPH model was successfully established in rats treated with CH for 21 days. In CHPH rats, the structure of TJ was destroyed, the function of PMVECs barrier was decreased, the intercellular permeability was increased, the expression of TJ-related proteins were significantly decreased and the expression of TRPV4 was significantly increased (P < 0.01). The amplitude of [Ca2+]i in PMVECs of CHPH rats was significantly increased after activation of TRPV4. The inhibition ratio of HC on [Ca2+]i in PMVECs of CHPH rats was significantly higher than that in normal PMVECs. TRPV4 specific inhibitor HC reversed the increase of PMVECs permeability and increased the expression of three TJ-related proteins in CHPH rats (P < 0.01, P < 0.05). These results suggest that TRPV4 channel can induce endothelial dysfunction by increasing the [Ca2+]i, resulting in the destruction of TJ structure and the decrease of TJ-related proteins expression on PMVECs in CHPH rats.

Key words: pulmonary hypertension; pulmonary microvascular endothelial cells; tight junction; Ca2+; TRPV4

Received: 2020-11-29　　Accepted: 2021-03-22

Corresponding author: 林默君　　E-mail: mjlin@mail.fjmu.edu.cn

Citing This Article：

JIAO Hai-Xia, YUAN Sheng-Xia, HUANG Yan-Zhen, SU Qiao-Wen, HE Rui-Lan, WU Zhi-Juan, LIN Mo-Jun. TRPV4 channel mediates the increase of pulmonary microvascular endothelial permeability in rats with chronic hypoxic pulmonary hypertension. Acta Physiol Sin 2021; 73 (6): 867-877 (in Chinese with English abstract).