Selective sinoatrial node optical mapping to investigate the mechanism of sinus rate acceleration

Shien-Fong Lin*, Tetsuji Shinohara, Boyoung Joung, Peng Sheng Chen

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Studies using isolated sinoatrial node (SAN) cells indicate that rhythmic spontaneous sarcoplasmic reticulum Ca release (Ca clock) plays an important role in SAN automaticity. However, it is difficult to translate these findings into intact SAN because the SAN is embedded in the right atrium (RA). Cross contamination of the optical signals between SAN and RA prevented the definitive testing of Ca clock hypothesis in intact SAN. We use a novel approach to selectively map intact SAN to examine the Ca clock function in intact RA. We simultaneously mapped intracellular Ca (Cai) and membrane potential (Vm) in 7 isolated, Langendorff perfused normal canine RA. Electrical conduction from the SAN to RA was inhibited with high potassium (10 mmol/L) Tyrode's solution, allowing selective optical mapping of Vm and Cai of the SAN. Isoproterenol (ISO, 0.03 μmol/L) decreased cycle length of the sinus beats from 586±17 ms at baseline to 366±32 ms, and shifted the leading pacemaker site from the middle or inferior SAN to the superior SAN in all RAs. The Cai upstroke preceded the Vm in the leading pacemaker site by up to 18±2 ms. ISO-induced changes to SAN were inhibited by ryanodine (3 μmol/L), but not ZD7288 (3 μmol/L), a selective If blocker. We conclude that a high extracellular potassium concentration results in intermittent SAN-RA conduction block, allowing selective optical mapping of the intact SAN. Acceleration of Ca cycling in the superior SAN underlies the mechanism of sinus tachycardia during sympathetic stimulation.

Original languageEnglish
Title of host publicationPhotonic Therapeutics and Diagnostics VII
DOIs
StatePublished - 12 Apr 2011
EventPhotonic Therapeutics and Diagnostics VII - San Francisco, CA, United States
Duration: 22 Jan 201124 Jan 2011

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume7883
ISSN (Print)1605-7422

Conference

ConferencePhotonic Therapeutics and Diagnostics VII
CountryUnited States
CitySan Francisco, CA
Period22/01/1124/01/11

Keywords

  • calcium
  • nervous system, sympathetic
  • sarcoplasmic reticulum
  • sinoatrial node

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    Lin, S-F., Shinohara, T., Joung, B., & Chen, P. S. (2011). Selective sinoatrial node optical mapping to investigate the mechanism of sinus rate acceleration. In Photonic Therapeutics and Diagnostics VII [78832Z] (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 7883). https://doi.org/10.1117/12.873606