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Proceedings Paper

Selective sinoatrial node optical mapping to investigate the mechanism of sinus rate acceleration
Author(s): Shien-Fong Lin; Tetsuji Shinohara; Boyoung Joung M.D.; Peng-Sheng Chen
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Paper 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.

Paper Details

Date Published: 17 February 2011
PDF: 7 pages
Proc. SPIE 7883, Photonic Therapeutics and Diagnostics VII, 78832Z (17 February 2011); doi: 10.1117/12.873606
Show Author Affiliations
Shien-Fong Lin, Indiana Univ. School of Medicine (United States)
Tetsuji Shinohara, Indiana Univ. School of Medicine (United States)
Boyoung Joung M.D., Indiana Univ. School of Medicine (United States)
Peng-Sheng Chen, Indiana Univ. School of Medicine (United States)

Published in SPIE Proceedings Vol. 7883:
Photonic Therapeutics and Diagnostics VII
Kenton W. Gregory M.D.; Nikiforos Kollias; Andreas Mandelis; Henry Hirschberg M.D.; Hyun Wook Kang; Anita Mahadevan-Jansen; Brian Jet-Fei Wong M.D.; Justus F. R. Ilgner M.D.; Bodo E. Knudsen M.D.; E. Duco Jansen; Steen J. Madsen; Guillermo J. Tearney; Bernard Choi; Haishan Zeng; Laura Marcu, Editor(s)

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