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Updated: Jul 26, 2026

Optical Mapping of Intra-Sarcoplasmic Reticulum Ca2+ and Transmembrane Potential in the Langendorff-perfused Rabbit Heart
Published on: September 10, 2015
Properties of the sarcoplasmic reticulum Ca(2+)-pump in coronary artery skinned smooth muscle
A B Elmoselhi1, M Blennerhassett, S E Samson
1Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Abstract:
Pig coronary artery cultured smooth muscle cells were skinned using saponin. In the presence of an ATP-regenerating system and oxalate, the skinned cells showed an ATP-dependent azide insensitive Ca(2+)-uptake which increased linearly with time for > 1 h. The Ca(2+)-uptake occurred with Km values of 0.20 +/- 0.03 microM for Ca2+ and 400 +/- 34 microM for MgATP2-. Thapsigargin and cyclopiazonic acid inhibited this uptake with IC50 values of 0.13 +/- 0.02 and 0.56 +/- 0.04 microM, respectively. These properties of SR Ca(2+)-pump are similar to those reported for membrane fractions isolated from fresh smooth muscle of coronary artery and other arteries. However, optimum pH of the uptake in the skinned cells (6.2) was lower than that reported previously using isolated membranes (6.4-6.8).
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