Various reports have demonstrated that the sphingolipids sphingosine and sphingosine-1-phosphate are able to induce Ca2+ release from intracellular stores in a similar way to second messengers. Here, we have used the sea urchin egg homogenate, a model system for the study of intracellular Ca2+ release mechanisms, to investigate the effect of these sphingolipids. While ceramide and sphingosine-1...

The skeletal muscle calcium release channel, ryanodine receptor, is activated by calcium-free calmodulin and inhibited by calcium-bound calmodulin. Previous biochemical studies from our laboratory have shown that calcium-free calmodulin and calcium bound calmodulin protect sites at amino acids 3630 and 3637 from trypsin cleavage (Moore, C. P., Rodney, G., Zhang, J. Z., Santacruz-Toloza, L., Str...

The ryanodine receptor is the main Ca(2+)-release structure in skeletal and cardiac sarcoplasmic reticulum. In both tissues, phosphorylation of the ryanodine receptor has been proposed to be involved in the regulation of Ca2+ release. In the present study, we have examined the ability of the purified cardiac ryanodine receptor to serve as a substrate for phosphorylation by exogenously added cat...

The subcellular distribution of the Ca(2+)-release channel/ryanodine receptor in adult rat papillary myofibers has been determined by immunofluorescence and immunoelectron microscopical studies using affinity purified antibodies against the ryanodine receptor. The receptor is confined to the sarcoplasmic reticulum (SR) where it is localized to interior and peripheral junctional SR and the corbu...

Background Malignant hyperthermia (MH), central core disease (CCD), exertional heat stroke (EHS) and late-onset axial myopathy have been attributed to mutations in ryanodine receptor type 1 (RYR1). The RyR1 protein is over 5000 amino acid residues long, making manipulation of the mammalian gene difficult. The ryanodine receptor in Caenorhabditis elegans is UNC-68, which has 40% amino acid ident...

The ryanodine receptor was isolated from the sarcoplasmic reticulum of crayfish skeletal muscle. Ryanodine binding to the native fraction was measured by Scatchard analysis and values of 60 nmol/l and 9 pmol/mg were obtained for KD and Bmax respectively. The identity of purified receptor was confirmed by electron microscopy, electrophoresis and incorporation into planar lipid bilayers. At least...

Caffeine robustly enhances transmitter release from the hippocampal mossy fiber terminals, although it remains uncertain whether calcium mobilization through presynaptic ryanodine receptors mediates this enhancement. In this study, we adopted a selective adenosine A1 blocker to assess relative contribution of A1 receptors and ryanodine receptors in caffeine-induced synaptic enhancement. Applica...

OBJECTIVE Recent evidence shows that calcium released from the sarcoplasmic reticulum (SR) plays an important role in the regulation of heart rate. The aim of this study was to investigate the subcellular distribution of ryanodine receptors in the guinea-pig sino-atrial (SA) node and to determine their functional role in the regulation of pacemaker frequency in response to beta-adrenoceptor sti...