Enhanced store-operated Ca²⁺ entry and TRPC channel expression in pulmonary arteries of monocrotaline-induced pulmonary hypertensive rats

Abstract

Here we further examine the involvement of TRPC and SOCE in PH with a widely used rat model of monocrotaline (MCT)-induced PAH. Rats developed severe PAH, right ventricular hypertrophy, and significant increase in store-operated TRPC1 and TRPC4 mRNA and protein in endothelium-denuded pulmonary arteries (PAs) 3 wk after MCT injection. Contraction of PA and Ca 2ϩ influx in PASMC evoked by store depletion using cyclopiazonic acid (CPA) were enhanced dramatically, consistent with augmented SOCE in the MCT-treated group. The time course of increase in CPA-induced contraction corresponded to that of TRPC1 expression. Endothelin-1 (ET-1)-induced vasoconstriction was also potentiated in PAs of MCT-treated rats. The response was partially inhibited by SOCE blockers, including Gd 3ϩ , La 3ϩ , and SKF-96365, as well as the general TRPC inhibitor BTP-2, suggesting that TRPC-dependent SOCE was involved. Moreover, the ET-1-induced contraction and Ca 2ϩ response in the MCT group were more susceptible to the inhibition caused by the various SOCE blockers. Hence, our study shows that MCTinduced PAH is associated with increased TRPC expression and SOCE, which are involved in the enhanced vascular reactivity to ET-1, and support the hypothesis that TRPC-dependent SOCE is an important pathway for the development of PH.canonical transient receptor potential 1; store-operated calcium channels; monocrotaline; pulmonary hypertension; endothelin-1 PULMONARY HYPERTENSION (PH) is a pathophysiological condition associated with a board spectrum of diseases of different pathological features and etiological mechanisms (53). Among them, pulmonary arterial hypertension (PAH) is a severe progressive form characterized by vasoconstriction, plexiform formation, and vascular cell proliferation and remodeling, resulting in elevated pulmonary vascular resistance, right ventricular hypertrophy, and eventually right heart failure and death (16). There are different types of PAH, including idiopathic (IPAH) and heritable PAH (53). PH owing to lung diseases and hypoxia is another category of PH, which includes PH associated with chronic obstructive pulmonary disease, sleep disorders, and chronic exposure to high altitude. PH in this group is generally mild to moderate, but it worsens the prognosis of the diseases (9, 41). The etiologic mechanisms of the various forms of PH are different, but they all have the common features of abnormalities in pulmonary vascular function, vascular cell proliferation, and remodeling, suggesting that they may share some important downstream signaling mechanisms in the process of disease development.Intracellular Ca 2ϩ signaling plays pivotal roles in the regulation of numerous physiological and pathophysiological processes, including contraction, proliferation, hypertrophy, and migration, in pulmonary arterial smooth muscle cell (PASMC) (45). Previous studies indicate that there are major alterations in ion channel expression and Ca 2ϩ homeostasis, such as membrane depolarization, downregulation of voltage-gated K ϩ chan...

Store-operated channels in the pulmonary circulation of high- and low-altitude neonatal lambs

“…These results are consistent with previous studies reporting that TRPC4 is a SOC component in pulmonary artery smooth muscle cells (60) and could be responsible for the robust acute hypoxic vasoconstrictor response of distal pulmonary arteries (27). Furthermore, TRPC4 upregulation is also observed in rats with monocrotalineinduced pulmonary hypertension (26). Other authors have observed that hypoxia evokes an increase in TRPC1 and TRPC6 expression in cultured pulmonary artery smooth muscle cells from adult rat and mouse (25,52).…”

“…An enhanced role of SOC is also seen in pulmonary artery myocytes from fetal sheep with increased shear stress and pulmonary hypertension induced by ductus arteriosus ligation (41), as well as in cultured pulmonary arteries from adult rats with pulmonary hypertension (26).…”

Effects of chronic exposure to cigarette smoke on canonical transient receptor potential expression in rat pulmonary arterial smooth muscle

“…Previously, Feng et al (4) found that mutant worms lacking TRPC channels were defective in their response to nicotine and such a defect could be rescued by a human TRPC channel, which revealed an unexpected role of TRPC channels in regulating nicotine-dependent behavior. We and others have previously confirmed that the proteins encoded by TRPC genes are components of the store-operated calcium channel (SOCC) and receptor-operated calcium channel (ROCC) (10,31). During PH pathophysiological progress, enhanced Ca 2ϩ influx through SOCC, termed store-operated calcium entry (SOCE), results in elevated intracellular calcium concentration ([Ca 2ϩ ] i ) and subsequently promotes PASMCs migration and proliferation, leading to hypertrophy of PASMCs and increase of pulmonary vascular tone (32,40,41).…”

Ginsenoside Rb1 Attenuates Agonist-Induced Contractile Response via Inhibition of Store-Operated Calcium Entry in Pulmonary Arteries of Normal and Pulmonary Hypertensive Rats

“…Male Sprague-Dawley rats were placed in a hypoxic chamber and exposed to either normoxia or normobaric hypoxia 10% O 2 for 3 weeks. MCT-induced PH was generated by a single intraperitoneal injection of MCT (50mg/kg) [36]. Twenty-one days after MCT injection or CH exposure, rats were anesthetized with urethane (1 g/kg).…”

“…Pulmonary arterial smooth muscle cells (PASMCs) were enzymatically isolated and transiently cultured as previously described [34,36]. Briefly, lungs were removed and transferred to a petri dish filled with cold HEPES-buffered salt solution (HBSS) containing (in mM) 130 NaCl, 5 KCl, 1.2 MgCl 2 , 1.5 CaCl 2 , 10 HEPES, and 10 glucose, pH 7.4 (adjusted with NaOH).…”