The role of TRPM4 in ventricular cardiomyocytes

Abstract

TRPM4 is a Ca2+ activated non‐selective cation channel. Together with TRPM5 it's the only molecular candidate for this class of ion channels to date. Both genes are members of the Transient Receptor Potential (TRP) family of ion channels. We have shown previously, using Trpm4−/− mice, that this channel plays a critical role in setting the membrane potential, and consequently the driving force for Ca2+ entry in mast cells, which determines ultimately the strength of an allergic reaction. The role of CAN channels in excitable cells however is unclear. In this study we tested whether TRPM4 plays a role in cardiac muscle. We used the analysis of pressure‐volume loops to determine contractility properties in vivo. These results were confirmed in isolated papillary muscle. To determine the role of TRPM4 in cardiomyocytes, we used sharp intracellular micro‐electrodes to measure membrane potential in paced LV papillary muscle. We are currently analyzing the consequences of TRPM4 ablation for cellular signaling in isolated cardiomyocytes using the patch clamp technique.