The time course of the effects of phenylephrine (10 mumol/l) on force of contraction and on inositol phosphates in electrically driven left auricles from rat hearts labeled with [3H]inositol was studied. All experiments were performed in the presence of propranolol (1 mumol/l) and LiCl (10 mmol/l). Products measured after separation with high-performance liquid chromatography were inositol 1-ph...

Background: Astrocytes were conceived for decades only as supporting cells of the brain. However, the observation of Ca2+ waves in astrocyte synctitia, their neurotransmitter receptor expression and gliotransmitter secretion suggested a role in information handling, conception that has some controversies. Synaptic Neuron-Astrocyte metabotropic communication mediated by Inositol tris-phosphate (...

Inositol 1,4,5-trisphosphate 3-kinase (IP3K) catalyzes the adenosine triphosphate (ATP) dependent phosphorylation of inositol 1,4,5-trisphosphate (IP3) to inositol 1,3,4,5-tetrakisphosphate (IP4) and plays an important role in the regulation of intracellular calcium concentration. IP3 is a well-known second messenger that stimulates intracellular calcium mobilization, which is in turn responsib...

Barrera, Nelson P., Bernardo Morales, and Manuel Villalón. Plasma and intracellular membrane inositol 1,4,5-trisphosphate receptors mediate the Ca increase associated with the ATP-induced increase in ciliary beat frequency. Am J Physiol Cell Physiol 287: C1114–C1124, 2004. First published June 2, 2004; 10.1152/ajpcell. 00343.2003.—An increase in intracellular free Ca concentration ([Ca ]i) has ...

BACKGROUND Abnormal intracellular Ca2+ homeostasis occurs in chronic atrial fibrillation(AF). The intracellular Ca2+ concentration is regulated by ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors. Changes occur in ryanodine receptors in atrial tissue from patients in chronic AF. Whether AF patients have alterations in atrial IP3 receptors was investigated. METHODS IP3 receptor expre...

The in vitro contracture test (IVCT) is the only available diagnostic method at present for evaluation of malignant hyperthermia (MH) susceptibility. However, the disadvantage of the IVCT is that it is invasive. Several studies suggest that an altered inositol phosphate system is involved in the development of MH. A greater concentration of inositol 1,4,5-trisphosphate (1,4,5-IP3) was found in ...

IP3 analogs were synthesized by the modification of phosphate at the 1-position, and their affinity for the IP3 receptor was analyzed by means of surface plasmon resonance measurements. Our results suggest that a hydrophobic and charged moiety linked to this position enhances the affinity for the IP3 receptor.

Ca(2+) liberation from the endoplasmic reticulum mediated by inositol trisphosphate receptor/channels (IP3Rs) in response to production of the second messenger IP3 regulates numerous signaling pathways. However, estimates of resting and physiologically relevant cytosolic concentrations of IP3 vary appreciably. Here we directly address this question, taking advantage of the large size of Xenopus...

Sperm-induced activation of mammalian eggs is associated with a transient increase in the concentration of intracellular Ca2+. The role of inositol 1,4,5-trisphosphate (IP3)-mediated release of Ca2+ from intracellular stores during mouse egg activation was examined in the present study by determining the effects of microinjected monoclonal antibody (mAb) 18A10, which binds to the IP3 receptor a...