Key result
Inorganic phosphate inhibits sarcoplasmic reticulum Ca2+ uptake by activating a ryanodine-insensitive Ca2+ efflux pathway.
Why the study?
The effects of inorganic phosphate and oxalate on sarcoplasmic reticulum Ca2+ uptake and release in cardiac trabeculae were not fully understood.
Population
Ventricular trabeculae from the right ventricle of rat heart skinned with saponin
Comparison
Inorganic phosphate (30 or 60 mM) and oxalate (2, 10, or 20 mM) vs control conditions
Design
Preclinical experimental study
Authors
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Pi reduces SR Ca2+ release in skinned rat trabeculae; leaves open any role in human contractile dysfunction.
Inorganic phosphate decreases releasable calcium from the sarcoplasmic reticulum by activating a ryanodine-insensitive efflux pathway rather than by precipitating calcium phosphate within the lumen.
Steele et al. (1996) studied this question. Inorganic phosphate and oxalate was evaluated on Ca2+ uptake and release by the sarcoplasmic reticulum. Inorganic phosphate inhibits net sarcoplasmic reticulum Ca2+ uptake by activating a ryanodine-insensitive Ca2+ efflux pathway rather than inhibiting Ca2+ uptake or precipitating calcium phosphate.
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