Cytosolic calcium in the ischemic rabbit heart: Assessment by pH- and temperature-adjusted rhod-2 spectrofluorometry

Citations of this article
Mendeley users who have this article in their library.


Objectives: Cytosolic calcium ([Ca2+]i) mediates ischemia-reperfusion (I/R) injury, but magnitude and time course of I/R-induced [Ca2+]i overload remain unclear. Fluorescent indicators are commonly used to measure [Ca2+]i, and have a dissociation constant (Kd) that depends on pH and temperature. We hypothesized that changes of Kd during I/R lead to misleading interpretations of [Ca2+]i recordings. Methods: (1) In isolated rabbit hearts (n=4 each), intracellular pH was measured during I/R at 37°C, 20°C, and 4°C with and without cardioplegic arrest by 31P-NMR-spectroscopy. (2) Kd for rhod-2 and calcium was determined at varying pH and temperature in in vitro experiments. (3) Isolated rabbit hearts were subjected to I/R, and [Ca2+]i was recorded by surface rhod-2 spectrofluorometry. Finally, [Ca2+] i was computed using either the conventional Kd, or the pH- and temperature-adjusted Kd. Results: Kd(Ca 2+Rhod-2) remained stable between pH 7.1 and 6.8, but increased exponentially with lower pH and/or temperature. Calculations using a static Kd indicated that [Ca2+]i rose only mildly during warm ischemia and did not rise during cardioplegic arrest, while a large Ca2+ influx appeared to occur during early reperfusion. When the pH and temperature-adjusted Kd was used for calculation, [Ca 2+]i rose significantly during ischemia (431±37% during 20 min 37°C ischemia, and 78±19% during 20 min cardioplegic arrest at 20°C). During early reperfusion, [Ca2+]i decreased rapidly, without significant further [Ca2+]i elevation. Conclusions: In contrast to previous reports, [Ca2+] i accumulation occurs during unprotected ischemia as well as hypothermic ischemia with cardioplegic arrest, without further net Ca 2+ influx on reperfusion. This finding has important implications for timing of protective strategies during myocardial ischemia. © 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.




Stamm, C., Friehs, I., Choi, Y. H., Zurakowski, D., McGowan, F. X., & Del Nido, P. J. (2003). Cytosolic calcium in the ischemic rabbit heart: Assessment by pH- and temperature-adjusted rhod-2 spectrofluorometry. Cardiovascular Research, 59(3), 695–704.

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free