The monophasic action potential upstroke: a means of characterizing local conduction

Circulation
J H LevineJ F Spear

Abstract

The upstrokes of monophasic action potentials (MAPs) recorded with an extracellular pressure electrode were characterized in isolated canine tissue preparations in vitro. The characteristics of the MAP upstroke were compared with those of the local action potential foot as well as with the characteristics of approaching electrical activation during uniform and asynchronous conduction. The upstroke of the MAP was exponential during uniform conduction. The time constant of rise of the MAP upstroke (TMAP) correlated with that of the action potential foot (Tfoot): TMAP + 1.01 Tfoot + 0.50; r2 = .80. Furthermore, changes in Tfoot with alterations in cycle length were associated with similar changes in TMAP: Tfoot = 1.06 TMAP - 0.11; r2 = .78. In addition, TMAP and Tfoot both deviated from exponential during asynchronous activation; the inflections that developed in the MAP upstroke correlated in time with intracellular action potential upstrokes that were asynchronous in onset in these tissues. Finally, the field of view of the MAP was determined and was found to be dependent in part on tissue architecture and the space constant. Specifically, the field of view of the MAP was found to be greater parallel compared with transverse to ...Continue Reading

References

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Citations

Feb 1, 1997·Journal of Pharmacological and Toxicological Methods·T D BarrettM J Walker
Feb 1, 1990·Pacing and Clinical Electrophysiology : PACE·N KanaanA Kadish
Mar 1, 1996·Pacing and Clinical Electrophysiology : PACE·S YuanC Blomström-Lundqvist
Mar 1, 1994·Journal of Cardiovascular Electrophysiology·S YuanS B Olsson
Jun 10, 2011·Journal of Molecular and Cellular Cardiology·Ryuji TsuburayaHiroaki Shimokawa
May 1, 1991·Progress in Cardiovascular Diseases·M R Franz

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