Selective sinoatrial node optical mapping and the mechanism of sinus rate acceleration

Tetsuji Shinohara, Hyung Wook Park, Boyoung Joung, Mitsunori Maruyama, Su Kiat Chua, Seongwook Han, Mark J. Shen, Peng-Sheng Chen, Shien-Fong Lin

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Background: Studies using isolated sinoatrial node (SAN) cells indicate that rhythmic spontaneous sarcoplasmic reticulum calcium release (Ca clock) plays an important role in SAN automaticity. In the intact SAN, cross-contamination of optical signals from the SAN and the right atrium (RA) prevent the definitive testing of Ca clock hypothesis. The aim of this study was to use a novel approach to selectively mapping the intact SAN to examine the Ca clock mechanism. Methods and Results: We simultaneously mapped intracellular Ca (Cai) and membrane potential (Vm) in 10 isolated, Langendorff-perfused normal canine RAs. The excitability of the RA was suppressed with high-potassium Tyrode's solution, allowing selective optical mapping of Vm and Cai of the SAN. Isoproterenol (ISO, 0.03 μmol/L) decreased the cycle length of the sinus beats, 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. Conclusions: We conclude that, in the isolated canine RA, a high extracellular potassium concentration can suppress atrial excitability thus leading to 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
Pages (from-to)309-316
Number of pages8
JournalCirculation Journal
Volume76
Issue number2
DOIs
StatePublished - 2012

Fingerprint

Sinoatrial Node
Heart Atria
Canidae
Voltage-Sensitive Dye Imaging
Potassium
Sinus Tachycardia
Ryanodine
Sarcoplasmic Reticulum
Isoproterenol
Membrane Potentials

Keywords

  • Calcium
  • Potassium
  • Sarcoplasmic reticulum
  • Sinoatrial node
  • Sympathetic nervous system

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

Cite this

Selective sinoatrial node optical mapping and the mechanism of sinus rate acceleration. / Shinohara, Tetsuji; Park, Hyung Wook; Joung, Boyoung; Maruyama, Mitsunori; Chua, Su Kiat; Han, Seongwook; Shen, Mark J.; Chen, Peng-Sheng; Lin, Shien-Fong.

In: Circulation Journal, Vol. 76, No. 2, 2012, p. 309-316.

Research output: Contribution to journalArticle

Shinohara, T, Park, HW, Joung, B, Maruyama, M, Chua, SK, Han, S, Shen, MJ, Chen, P-S & Lin, S-F 2012, 'Selective sinoatrial node optical mapping and the mechanism of sinus rate acceleration', Circulation Journal, vol. 76, no. 2, pp. 309-316. https://doi.org/10.1253/circj.CJ-11-0734
Shinohara, Tetsuji ; Park, Hyung Wook ; Joung, Boyoung ; Maruyama, Mitsunori ; Chua, Su Kiat ; Han, Seongwook ; Shen, Mark J. ; Chen, Peng-Sheng ; Lin, Shien-Fong. / Selective sinoatrial node optical mapping and the mechanism of sinus rate acceleration. In: Circulation Journal. 2012 ; Vol. 76, No. 2. pp. 309-316.
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