Transient Loss of Voltage Control of Ca Release in the Presence of Maurocalcine in Skeletal Muscle

Transient loss of voltage control of Ca2+ release in the presence of maurocalcine in skeletal muscle.

In skeletal muscle, sarcoplasmic reticulum (SR) calcium release is controlled by the plasma membrane voltage through interactions between the voltage-sensing dihydropyridine receptor (DHPr) and the ryanodine receptor (RYr) calcium release channel. Maurocalcine (MCa), a scorpion toxin peptide presenting some homology with a segment of a cytoplasmic loop of the DHPr, has been previously shown to ...

Differential effects of maurocalcine on Ca2+ release events and depolarization-induced Ca2+ release in rat skeletal muscle.

Maurocalcine (MCa), a 33 amino acid toxin obtained from scorpion venom, has been shown to interact with the isolated skeletal-type ryanodine receptor (RyR1) and to strongly modify its calcium channel gating. In this study, we explored the effects of MCa on RyR1 in situ to establish whether the functional interaction of RyR1 with the voltage-sensing dihydropyridine receptor (DHPR) would modify t...

Redox-sensitive stimulation of type-1 ryanodine receptors by the scorpion toxin maurocalcine.

The scorpion toxin maurocalcine acts as a high affinity agonist of the type-1 ryanodine receptor expressed in skeletal muscle. Here, we investigated the effects of the reducing agent dithiothreitol or the oxidizing reagent thimerosal on type-1 ryanodine receptor stimulation by maurocalcine. Maurocalcine addition to sarcoplasmic reticulum vesicles actively loaded with calcium elicited Ca²⁺ relea...

Charged surface area of Maurocalcine determines its interaction with the skeletal muscle calcium release channel

Major contribution of sarcoplasmic reticulum Ca depletion during long-lasting activation of skeletal muscle

Depolarization of skeletal muscle fiber induces the release of Ca ions from the SR through RyR Ca release channels, which in turn activate contraction. Activity of the RyR is a tightly voltage-controlled process that involves the dihydropyridine receptors (DHPRs) anchored in the t-tubules, which act as voltage sensors and transduce membrane potential change into RyR opening (Ríos and Pizarro, 1...