Potentiation of Fractional Sarcoplasmic Reticulum Calcium Release by Total and Free Intra-Sarcoplasmic Reticulum Calcium Concentration

Calcium release from aortic sarcoplasmic reticulum.

The ability of ionsitol 1,4,5-trisphosphate (IP3) and other inositol phosphates to induce calcium release from canine aortic sarcoplasmic reticulum vesicles was examined. Using the calcium indicator chlorotetracycline or antipyrylazo III, aortic vesicles were shown to accumulate calcium in the presence of ATP, and then release approximately 25% of the intravesicular calcium upon addition of 7 m...

Calcium release from the sarcoplasmic reticulum.

Illuminating sarcoplasmic reticulum calcium.

The bulk of the Ca 2 that activates contraction in the heart comes from the sarcoplasmic reticulum (SR). Calcium is released by the process of Ca -induced Ca release (CICR) in which the entry of a small amount of Ca across the cell membrane triggers the release of much more from the SR. This mechanism depends on the fact that Ca entry from the extracellular fluid (via the L-type Ca current) inc...

Sarcoplasmic Reticulum Calcium Uptake

To investigate the mechanism underlying postischemic cardiac dysfunction (myocardial stunning), contractility and adenine nucleotide metabolism were studied in three groups of isolated perfused rabbit hearts (control, ischemic, and reperfused), whereas Ca2` uptake by the sarcoplasmic reticulum (SR) was measured in homogenates obtained from them. The hearts were Langendorff-perfused under consta...

Luminal calcium regulation of calcium release from sarcoplasmic reticulum.

This article discusses how changes in luminal calcium concentration affect calcium release rates from triad-enriched sarcoplasmic reticulum vesicles, as well as single channel opening probability of the ryanodine receptor/calcium release channels incorporated in bilayers. The possible participation of calsequestrin, or of other luminal proteins of sarcoplasmic reticulum in this regulation is ad...