Characterization of TRP Channel Expression in Native Human Pulmonary Arterial and Airway Smooth Muscle

Transient receptor potential (TRP) gene superfamily is known to encode a large repertoire of cation channels pertinent to diverse physiological functions in the cardiovascular and pulmonary systems. Characterization of these channels was mainly performed in experimental animals, and their expression profiles have not been examined systematically in native human tissues. Here we quantified the expression of the canonical (TRPC), melastatin- (TRPM) and vanilloid-related (TRPV) TRP channel mRNA in human small (~2 μm) and distal (<1 μm) pulmonary arterial (PASM) and airway smooth muscle (ASM) from five organ donors. Quantitative real-time RT-PCR showed that the expression of TRPC6 was most prominent in small and distal human PASM and ASM, followed by TRPC1, TRPC3, and TRPC4. TRPC5, and TRPC7 were minimally expressed. For TRPM channels, the order of expression was TRPM7=TRPM4>TRPM2=TRPM3, with only very low levels of TRPM5, TRPM6 and TRPM8 expression. For TRPV channels, TRPV2 mRNA level was the highest in PASM and ASM, except TRPV4 was also prominently expressed in ASMs. Overall speaking, the expression profiles of the TRPC, TRPM, and TRPV mRNAs were similar in native human PASM and ASM, and compatible with those in commercially available cultured human PASM and ASM cells. Our results laid the groundwork for future studies on the regulation of TRP channels in native human PASM and ASM.