Low [ATP] and elevated [Mg2 ] reduce depolarization-induced Ca2 release in rat skinned skeletal muscle fibres.
R Blazev, GD Lamb
The Journal of Physiology | Published : 1999
1. This study examined whether reduced [ATP], raised [Mg2+] and the presence of the metabolites AMP and inosine monophosphate (IMP) affected depolarization-induced Ca2+ release from the sarcoplasmic reticulum (SR) in mechanically skinned skeletal muscle fibres of the rat. The amount of Ca2+ released was determined from the extent of SR Ca2+ depletion following a depolarization in the specified conditions with 2 mM free EGTA present to chelate released Ca2+. 2. In the presence of 8 mM total ATP and 1 mM free Mg2+, most of the SR Ca2+ could be released by a single (2-3 s) depolarization. Paired comparisons in the same fibres showed that raising the [Mg2+] from 1 to 3 mM reduced the total amoun..View full abstract