Functional behaviour of the ryanodine receptor/Ca(2+)-release channel in vesiculated derivatives of the junctional membrane of terminal cisternae of rabbit fast muscle sarcoplasmic reticulum.

We have devised a novel procedure, employing Chaps rather than Triton [Costello B., Chadwick C., Saito A.

Ratio of dihydropyridine to ryanodine receptors in mammalian and frog twitch muscles in relation to the mechanical hypothesis of excitation-contraction coupling.

An indirect argument in favour of the mechanical hypothesis of excitation-contraction (EC) coupling [Schneider & Chandler (1973) Nature 242, 244-246] is the fixed stoichiometry between the voltage-driven dihydropyridine receptor (DHP-R) on the transverse tubule (TT) and the ryanodine-sensitive Ca2+ channel (RyR) of sarcoplasmic reticulum (SR) terminal cisternae (TC), based mainly on the structural arrangement described by Block et al. at junctional triads of toadfish swimbladder muscle [Block, B., et al.

Quantitation of ryanodine receptor of rabbit skeletal muscle, heart and brain.

The total number of high-affinity ryanodine receptor (RyR) binding sites present in skeletal and cardiac muscle and in brain tissue of the rabbit was determined by [3H]ryanodine binding to subfractions obtained by differential centrifugation of homogenates prepared in a low-ionic strength medium, containing 0.5% Chaps. In all three tissues at least 80% of [3H]ryanodine binding was recovered in the total membrane (TM) fraction obtained by centrifuging between 650 g for 10 min and 120,000 x g for 90 min.

Biochemical characteristics of free and junctional sarcoplasmic reticulum and of transverse tubules in human skeletal muscle.

The microsomal fraction of normal human skeletal muscle was subfractionated by isopycnic sucrose-density centrifugation, using the procedure originally described by Saito et al. for rabbit fast muscle, and specific markers of the junctional face membrane of terminal cisternae (TC) (ryanodine receptor, high-molecular-weight feet proteins and membrane-associated calcium-binding protein calsequestrin), of the sarcoplasmic reticulum (SR) Ca-pump membrane (chicken antibody to rabbit Ca-ATPase), and of transverse tubules (TT) (dihydropiridine receptor, membrane cholesterol), respectively. The results show that isolated TC from human skeletal muscle share extensive morphological characteristics, protein composition, as well as Ca-release properties with rabbit TC, as tested with an inhibitor (Ruthenium red) and an activator (doxorubicin) of SR Ca-release.