TRPV4 and pulmonary arterial hypertension: We found that the expression of Ca2+-permeable/sensitive channels and receptors, transient receptor potential (TRP) canonical channels (TRPC6) (24, 46, 47), TRP vanilloid channels (TRPV1 and TRPV4) (48, 49), TRP melastatin channels (TRPM7) (48), Orai/STIM channels (Orai1, Orai2, and STIM2) (46), and Ca2+-sensing receptors (26, 50, 51), was up-regulated, and thus, involved in abnormal Ca2+ events in PAH.