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Original Article

Korean J Physiol Pharmacol 2017; 21(1): 133-140

Published online January 1, 2017 https://doi.org/10.4196/kjpp.2017.21.1.133

Copyright © The Korean Journal of Physiology & Pharmacology.

Calcium permeability of transient receptor potential canonical (TRPC) 4 channels measured by TRPC4-GCaMP6s

Juyeon Ko1,#, Jongyun Myeong1,#, Dongki Yang2, and Insuk So1,*

1Department of Physiology, Seoul National University College of Medicine, Seoul 03080, 2Department of Physiology, College of Medicine, Gachon University, Incheon 21936, Korea

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Conflicting evidence has been obtained regarding whether transient receptor potential cation channels (TRPC) are store-operated channels (SOCs) or receptor-operated channels (ROCs). Moreover, the Ca/Na permeability ratio differs depending on whether the current-voltage (I-V) curve has a doubly rectifying shape or inward rectifying shape. To investigate the calcium permeability of TRPC4 channels, we attached GCaMP6s to TRPC4 and simultaneously measured the current and calcium signals. A TRPC4 specific activator, (–)-englerin A, induced both current and calcium fluorescence with the similar time course. Muscarinic receptor stimulator, carbachol, also induced both current and calcium fluorescence with the similar time course. By forming heteromers with TRPC4, TRPC1 significantly reduced the inward current with outward rectifying I-V curve, which also caused the decrease of calcium fluorescence intensity. These results suggest that GCaMP6s attached to TRPC4 can detect slight calcium changes near TRPC4 channels. Consequently, TRPC4-GCaMP6s can be a useful tool for testing the calcium permeability of TRPC4 channels.

Keywords: Calcium, GCaMP6s, Receptor-operated channels, TRPC1/4 heteromer, TRPC4