STIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node.

Conference Paper

Cardiac pacemaking is governed by specialized cardiomyocytes located in the sinoatrial node (SAN). SAN cells (SANCs) integrate voltage-gated currents from channels on the membrane surface (membrane clock) with rhythmic Ca(2+) release from internal Ca(2+) stores (Ca(2+) clock) to adjust heart rate to meet hemodynamic demand. Here, we report that stromal interaction molecule 1 (STIM1) and Orai1 channels, key components of store-operated Ca(2+) entry, are selectively expressed in SANCs. Cardiac-specific deletion of STIM1 in mice resulted in depletion of sarcoplasmic reticulum (SR) Ca(2+) stores of SANCs and led to SAN dysfunction, as was evident by a reduction in heart rate, sinus arrest, and an exaggerated autonomic response to cholinergic signaling. Moreover, STIM1 influenced SAN function by regulating ionic fluxes in SANCs, including activation of a store-operated Ca(2+) current, a reduction in L-type Ca(2+) current, and enhancing the activities of Na(+)/Ca(2+) exchanger. In conclusion, these studies reveal that STIM1 is a multifunctional regulator of Ca(2+) dynamics in SANCs that links SR Ca(2+) store content with electrical events occurring in the plasma membrane, thereby contributing to automaticity of the SAN.

Full Text

Duke Authors

Cited Authors

  • Zhang, H; Sun, AY; Kim, JJ; Graham, V; Finch, EA; Nepliouev, I; Zhao, G; Li, T; Lederer, WJ; Stiber, JA; Pitt, GS; Bursac, N; Rosenberg, PB

Published Date

  • October 13, 2015

Published In

Volume / Issue

  • 112 / 41

Start / End Page

  • E5618 - E5627

PubMed ID

  • 26424448

Pubmed Central ID

  • PMC4611639

Electronic International Standard Serial Number (EISSN)

  • 1091-6490

Digital Object Identifier (DOI)

  • 10.1073/pnas.1503847112

Conference Location

  • United States