HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/2/H874    most recent 00785.2006v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Goel, M. Articles by Schilling, W. P. Search for Related Content PubMed PubMed Citation Articles by Goel, M. Articles by Schilling, W. P.

TRPC3 channels colocalize with Na⁺/Ca²⁺ exchanger and Na⁺ pump in axial component of transverse-axial tubular system of rat ventricle

¹Rammelkamp Center for Education and Research, MetroHealth Medical Center and ²Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio

Submitted 21 July 2006 ; accepted in final form 22 September 2006

Transient receptor potential canonical (TRPC) proteins form Ca²⁺-permeable, nonselective cation channels activated after stimulation of G protein-coupled membrane receptors linked to phospholipase C (PLC). Although the PLC/inositol phosphate signaling pathway is known to exist in heart, expression and subcellular distribution of TRPC channel proteins in ventricular myocardium have not been evaluated. Of the six members of the TRPC channel family examined here, only TRPC3 was found by Western blot analysis of membrane proteins from rodent or canine ventricle. Likewise, only TRPC3 was observed in immunofluorescence analysis of thin sections from rat ventricle. TRPC3 was also the only family member observed in neonatal rat ventricular myocytes in culture. In longitudinal sections of rat ventricle, TRPC3 was predominantly localized to the intercalated disk region of the myocyte. However, transverse sections through heart muscle or single isolated adult myocytes revealed TRPC3-specific labeling in a vast network of intracellular membranes, where it colocalized with the Na⁺-K⁺-ATPase (NKA) pump and the Na⁺/Ca²⁺ exchanger (NCX) but not with the ryanodine receptor or the sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) pump. Reciprocal immunoprecipitation assays from rat or canine ventricle showed that TRPC3 associates with NKA and NCX but not with the plasmalemmal Ca²⁺-ATPase pump. Immunoprecipitations from Sf9 insect cells heterologously expressing TRPC3, NKA, and NCX in various combinations revealed that NKA and NCX interact and that TRPC3 and NCX interact, but that TRPC3 does not directly associate with NKA. Together, these results suggest that TRPC3 is localized in the ventricular myocyte to the axial component of the transverse-axial tubular system, where it exists in a signaling complex that includes NCX and NKA.

ventricular myocytes; Ca²⁺ channels; immunohistochemistry; immunoprecipitation

This article has been cited by other articles:

				J. Huang, L. Hove-Madsen, and G. F. Tibbits SR Ca2+ refilling upon depletion and SR Ca2+ uptake rates during development in rabbit ventricular myocytes Am J Physiol Cell Physiol, December 1, 2007; 293(6): C1906 - C1915. [Abstract] [Full Text] [PDF]