We have investigated the interactions between the cAMP and inositol 1,4,5-trisphosphate (IP3)-Ca2+ signalling systems in the bovine iris sphincter by measuring the effects of beta-adrenergic and cholinergic muscarinic agonists and antagonists on cAMP formation, IP3 accumulation and muscle contraction-relaxation. (1) Addition of 5 microM isoproterenol (ISO) or forskolin (5 microM) consistently p...

Inositol 1,4,5-trisphosphate receptors (IP3 Rs) are expressed in nearly all animal cells, where they mediate the release of Ca(2+) from intracellular stores. The complex spatial and temporal organization of the ensuing intracellular Ca(2+) signals allows selective regulation of diverse physiological responses. Interactions of IP3 Rs with other proteins contribute to the specificity and speed of...

The stimulation of cells with agonists that activate phospholipase C, and hence increase the cytoplasmic concentration of inositol 1,4,5-trisphosphate (IP3), often produces complex intracellular Ca2+ signals, such as Ca2+ waves [1]. The key to understanding how Ca2+ waves propagate was the observation that the Ca2+ wave velocity and concentration gradient was maintained as the Ca2+ waves swept ...

We have used rats and mice with mutations in myosin-Va to evaluate the range and function of IP3-mediated Ca2+ signaling in dendritic spines. In these mutants, the endoplasmic reticulum and its attendant IP3 receptors do not enter the postsynaptic spines of parallel fiber synapses on cerebellar Purkinje cells. Long-term synaptic depression (LTD) is absent at the parallel fiber synapses of the m...

The regulation of cytosolic free Ca2+ concentration ([Ca2+]c) by intracellular organelles was studied in permeabilized bovine adrenal glomerulosa cells. Two compartments, with distinct characteristics, were able to pump Ca2+. A first pool, sensitive to ruthenium red and presumably mitochondrial, required respiratory chain substrates to maintain [Ca2+]c around 700 nM. Ca2+ efflux from this compa...

Background: Most primary hypothyroidism patients also experience inefficiency and irregularity. It is possible to understand the significance of myo-inositol in treating thyroid gland by relating it synthesis hormones. Study aimed estimate serum inositol 1,4,5-triphosphate (IP3) disorder through that level can shed light on whether accused inactivity at same time open doors for use as a treatme...

BACKGROUND Ca2+ waves allow effective delivery of intracellular Ca2+ signals to cytosolic targets. Propagation of these regenerative Ca2+ signals probably results from the activation of intracellular Ca2+ channels by the increase in cytosolic [Ca2+] that follows the opening of these channels. Such positive feedback is potentially explosive. Mechanisms that limit the spontaneous opening of intra...

Intercellular Ca2+ waves in astrocytes are thought to serve as a pathway of long-range signaling. The waves can propagate by the diffusion of molecules through gap junctions and across the extracellular space. In rat striatal astrocytes, the gap-junctional route was shown to be dominant. To analyze the interplay of the processes involved in wave propagation, a mathematical model of this system ...

The properties of inositol 1,4,5-trisphosphate (IP3)-dependent intracellular calcium oscillations in pancreatic acinar cells depend crucially on the agonist used to stimulate them. Acetylcholine or carbachol (CCh) cause high-frequency (10-12-s period) calcium oscillations that are superimposed on a raised baseline, while cholecystokinin (CCK) causes long-period (>100-s period) baseline spiking....