The ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors have previously been found to be intracellular Ca2+ release channels characterized by their large size and 4-fold symmetry. In this study, cardiomyocytes are found to have a different intracellular localization for the two receptors. At the level of light microscopy, the IP3 receptor is immunolocalized in rat ventricular cardiomyocy...

What are they? Members of a family of intracellular ligand-gated ion channels that allow Ca2+ release from intracellular stores. The endoplasmic reticulum (ER), or specialised regions of it, contains ATP-driven Ca2+ pumps which generate a high Ca2+ concentration in the ER lumen. When inositol 1,4,5-trisphosphate (IP3) binds to IP3 receptors, the channel region of the receptor opens, allowing Ca...

Associative long-term depression (LTD) at cerebellar parallel fiber-Purkinje cell synapses is sensitive to the temporal order in which the parallel fiber is coactivated with the climbing fiber input, but how order sensitivity is achieved is unknown. Here we show that the cerebellar inositol-1,4,5-trisphosphate (IP3) receptor, whose activation is required for LTD induction, is sensitive in situ ...

Cholesterol depletion reversibly abolishes carbachol-evoked Ca(2+) release from inositol (1,4,5)-trisphosphate (IP3)-sensitive stores, without affecting the distribution of IP3 receptors (IP3R) or endoplasmic reticulum, IP3 formation or responses to photolysis of caged IP3. Receptors that stimulate cAMP formation do not alone evoke Ca(2+) signals, but they potentiate those evoked by carbachol. ...

Large Ca2+ signals essential for cerebellar long-term depression (LTD) at parallel fiber (PF)-Purkinje cell synapses are known to be induced when PF activation precedes climbing fiber (CF) activation by 50-200 ms, consistent with cerebellar learning theories. However, large Ca2+ signals and/or LTD can also be induced by massive PF stimulation alone or by photolysis of caged Ca2+ or inositol 1,4...

The ability of ionsitol 1,4,5-trisphosphate (IP3) and other inositol phosphates to induce calcium release from canine aortic sarcoplasmic reticulum vesicles was examined. Using the calcium indicator chlorotetracycline or antipyrylazo III, aortic vesicles were shown to accumulate calcium in the presence of ATP, and then release approximately 25% of the intravesicular calcium upon addition of 7 m...

Fertilization of the immature, prophase I-arrested mouse oocyte produces multiple Ca2+ transients similar to those of the mature, metaphase II egg; however, the first Ca2+ transient is much lower in amplitude and shorter in duration. In contrast to prophase I-arrested oocytes, maturing oocytes fertilized after germinal vesicle breakdown have first Ca2+ transients similar to those of mature fert...

The phosphoinositide signaling pathway, which mediates neurotransmitter responses, was studied in Xenopus oocytes by recording membrane currents evoked using lightflash photolysis of caged inositol trisphosphate (caged IP3) to produce rapid and reproducible transients in intracellular IP3 levels. Photolysis of caged IP3 evoked currents which were carried largely by chloride ions and depended up...

Title of Document: THE PHARMACOLOGY AND DYNAMICS OF THE LIGHT-INDUCED CALCIUM SIGNAL IN LIMULUS VENTRAL PHOTORECEPTORS Youjun Wang, Doctor of Philosophy, 2007 Directed By: Professor Richard Payne, Neuroscience and Cognitive Neuroscience program The Limulus ventral photoreceptor is a model system for understanding inositol (1,4,5) trisphosphate (IP3) induced calcium (Ca ) release and the light r...

The internodal maize pulvinus responds to gravistimulation with differential cell elongation on the lower side. As the site of both graviperception and response, the pulvinus is an ideal system to study how organisms sense changes in orientation. We observed a transient 5-fold increase in inositol 1,4,5-trisphosphate (IP3) within 10 s of gravistimulation in the lower half of the pulvinus, indic...