TRPC1 and pulmonary arterial hypertension: TRPC1 also regulates vascular function, inducing vasoconstriction.141., 142., 143., 144. However, endothelial TRPC1 promotes vasodilation.145., 146., 147. TRPC1/4 heteromers regulate endothelial permeability in the lungs,148 and TRPC1 contributes to pulmonary hypertension,149,150 immune system regulation,151 cancer progression,152 and endocrine functions, such as parathyroid hormone secretion.153