Assessment of intra-SR free [Ca] and buffering in rat heart.

  title={Assessment of intra-SR free [Ca] and buffering in rat heart.},
  author={T Randolph Shannon and Donald M. Bers},
  journal={Biophysical journal},
  volume={73 3},
To measure the free intrasarcoplasmic reticulum [Ca] ([Ca]SR) in isolated rat cardiac microsomes, ventricular tissue was homogenized in the presence of the low-affinity Ca indicator furaptra. Stepwise increases in cuvette [Ca] ([Ca]c) in the presence of ATP caused progressive increases in steady-state intravesicular fluorescence ratio to a maximum (Rmax). Steady-state [Ca]SR/[Ca]c was approximately 7000. Therefore the resting [Ca]SR may approach 700 microM in the rat cardiac myocyte at [Ca]c… CONTINUE READING