Simultaneous measurement of Ca2+, contraction, and potential in cardiac myocytes

H. A. Spurgeon, M. D. Stern, G. Baartz, S. Raffaeli, R. G. Hansford, A. Talo, E. G. Lakatta, M. C. Capogrossi

Research output: Contribution to journalArticle


A system is described that can simultaneously record cytosolic Ca2+ concentration ([Ca2+](i)), cell length, and either membrane potential or current in single cardiac myocytes loaded with the fluorescent Ca2+ indicator indo-1. Fluorescence is excited by epi-illumination with 3.8-μs flashes of 350 ± 5 nm light from a xenon arc. Indo-1 fluorescence is measured simultaneously in spectral windows of 391-434 nm and 457-507 nm, and the ratio of indo-1 emission in the two bands is computed as a measure of [Ca2+](i) for each flash. With cells loaded with the permeant acetoxymethyl ester of indo-1, quantitation of [Ca2+](i) is not precise, owing to subcellular compartmentation of indo-1; however, the instrument would allow full quantitation if indo-1 free acid was introduced by microinjection. Simultaneously, cell length is measured on-line from the bright-field image of the cells. Because fluorescence collection is time gated during the brief flash, and red light (650-750 nm) is used for the bright-field image, cell length and [Ca2+](i) measurements are obtained simultaneously without cross talk. Membrane potential or current can be recorded simultaneously with indo-1 fluorescence and cell length via standard patch-clamping techniques.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number2 27-2
Publication statusPublished - 1990


  • cytosolic calcium ions
  • excitation-contraction coupling
  • fluorescent calcium ion indicators
  • indo-1

ASJC Scopus subject areas

  • Physiology

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    Spurgeon, H. A., Stern, M. D., Baartz, G., Raffaeli, S., Hansford, R. G., Talo, A., Lakatta, E. G., & Capogrossi, M. C. (1990). Simultaneous measurement of Ca2+, contraction, and potential in cardiac myocytes. American Journal of Physiology - Heart and Circulatory Physiology, 258(2 27-2).