BACKGROUND: Pulmonary hypertension (PH) is characterized by profound vascular remodeling and alterations in Ca(2+) homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Multiple transient receptor potential melastatin-related (TRPM) subtypes have been identified in vascular tissue. However, the changes in the expression and function of TRPM channels in pulmonary hypertension have not been characterized in detail. METHODS: We examined the expression of TRPM channels and characterized the functions of the altered TRPM channels in two widely used rat models of chronic hypoxia (CH)- and monocrotaline (MCT)-induced PH. RESULTS: CH-exposed and MCT-treated rats developed severe PH and right ventricular hypertrophy, with a significant decrease in TRPM8 mRNA and protein expression in pulmonary arteries (PAs). The downregulation of TRPM8 was associated with significant reduction in menthol-induced cation-influx. Time-profiles showed that TRPM8 down-regulation occurred prior to the increase of right ventricular systolic pressure (RVSP) and right ventricular mass index (RVMI) in CH-exposed rats, but these changes were delayed in MCT-treated rats. The TRPM8 agonist menthol induced vasorelaxation in phenylephrine-precontracted PAs, and the vasorelaxing effects were significantly attenuated in PAs of both PH rat models, consistent with decreased TRPM8 expression. CONCLUSION: Downregulation of TRPM8 may contribute to the enhanced vasoreactivity in PH.
BACKGROUND:Pulmonary hypertension (PH) is characterized by profound vascular remodeling and alterations in Ca(2+) homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Multiple transient receptor potential melastatin-related (TRPM) subtypes have been identified in vascular tissue. However, the changes in the expression and function of TRPM channels in pulmonary hypertension have not been characterized in detail. METHODS: We examined the expression of TRPM channels and characterized the functions of the altered TRPM channels in two widely used rat models of chronic hypoxia (CH)- and monocrotaline (MCT)-induced PH. RESULTS: CH-exposed and MCT-treated rats developed severe PH and right ventricular hypertrophy, with a significant decrease in TRPM8 mRNA and protein expression in pulmonary arteries (PAs). The downregulation of TRPM8 was associated with significant reduction in menthol-induced cation-influx. Time-profiles showed that TRPM8 down-regulation occurred prior to the increase of right ventricular systolic pressure (RVSP) and right ventricular mass index (RVMI) in CH-exposed rats, but these changes were delayed in MCT-treated rats. The TRPM8 agonist menthol induced vasorelaxation in phenylephrine-precontracted PAs, and the vasorelaxing effects were significantly attenuated in PAs of both PH rat models, consistent with decreased TRPM8 expression. CONCLUSION: Downregulation of TRPM8 may contribute to the enhanced vasoreactivity in PH.
Authors: Mo-Jun Lin; George P H Leung; Wei-Min Zhang; Xiao-Ru Yang; Kay-Pong Yip; Chung-Ming Tse; James S K Sham Journal: Circ Res Date: 2004-07-15 Impact factor: 17.367
Authors: Ying Yu; Ivana Fantozzi; Carmelle V Remillard; Judd W Landsberg; Naomi Kunichika; Oleksandr Platoshyn; Donna D Tigno; Patricia A Thistlethwaite; Lewis J Rubin; Jason X-J Yuan Journal: Proc Natl Acad Sci U S A Date: 2004-09-09 Impact factor: 11.205