Journal ArticleDOI
Permissive role of calcium in alpha 1-adrenergic stimulation of pineal phosphatidylinositol phosphodiesterase (phospholipase C) activity.
Reads0
Chats0
TLDR
Although Ca2+ is necessary for α1‐adrenergic stimulation of phospholipase C activity, an increase in [Ca2+]i alone is not sufficient to stimulate the activity of this enzyme, and that effects which A23187 and depolarizing concentrations of K+ have on pineal function probably do not involve stimulation of phosphate C activity.Abstract:
Activation of alpha 1-adrenergic receptors increases [Ca+2]i and phosphatidylinositol phosphodiesterase (phospholipase C) activity in the pinealocyte. In this report the receptor involved in the stimulation of phospholipase C activity was further characterized, and the role of Ca2+ in this effect was investigated in some detail. Phospholipase C activity was estimated by measuring the production of [3H]inositol phosphates by [3H]inositol-labelled dispersed pinealocytes in suspension culture. Norepinephrine stimulated [3H]inositol monophosphate production severalfold; this was blocked by alpha 1-adrenergic antagonists, including prazosin, WB 4101, and phenoxybenzamine, but by neither an alpha 2- nor a beta-adrenergic antagonist, confirming that an alpha 1-adrenoceptor is involved in the regulation of phosphatidylinositol hydrolysis. Treatment with the Ca2+ chelator, EGTA, or with inorganic Ca2+ blockers, including Co2+, Mn2+, and La3+, reduced the norepinephrine-stimulated response, suggesting that the alpha 1-adrenergic stimulation of phospholipase C activity is Ca2+ dependent. However, phospholipase C activity was not increased by elevating intracellular Ca2+ with either the Ca2+ ionophore A23187 or with depolarizing concentrations of K+. These results indicate that although Ca2+ is necessary for alpha 1-adrenergic stimulation of phospholipase C activity, an increase in [Ca2+]i alone is not sufficient to stimulate the activity of this enzyme, and that effects which A23187 and depolarizing concentrations of K+ have on pineal function probably do not involve stimulation of phospholipase C activity.read more
Citations
More filters
Journal ArticleDOI
Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters
TL;DR: The aim of this review is to gather together early and recent data on the effects of the nonadrenergic transmitters on modulation of melatonin synthesis, which reveals the variety of inputs that can be integrated by the pineal gland; what elements are crucial to deliver the very precise timing information to the organism.
Journal ArticleDOI
Night/day changes in pineal expression of >600 genes: central role of adrenergic/cAMP signaling.
Michael J. Bailey,Steven L. Coon,David Allan Carter,Ann Humphries,Jong-So Kim,Qiong Shi,Pascaline Gaildrat,Fabrice Morin,Surajit Ganguly,John B. Hogenesch,Joan L. Weller,Martin F. Rath,Morten Møller,Ruben Baler,David Sugden,Zoila G. Rangel,Peter J. Munson,David C. Klein +17 more
TL;DR: Functional categorization of the highly expressed and/or night/day differentially expressed genes identified clusters that are markers of specialized functions, including the immune/inflammation response, melatonin synthesis, photodetection, thyroid hormone signaling, and diverse aspects of cellular signaling and cell biology.
Journal ArticleDOI
Norepinephrine-Stimulated Increase in Na+,K+-ATPase Activity in the Rat Brain Is Mediated Through α1A-Adrenoceptor Possibly by Dephosphorylation of the Enzyme
TL;DR: It is proposed that norepinephrine acted on α1A‐adrenoceptor and increased intracellular calcium, which in the presence of calmodulin activated a Calmodulin‐dependent phosphatase, calcineurin, which possibly dephosphorylated Na+,K+‐ATPase and increased its activity.
Journal ArticleDOI
Multiple receptor regulation of cyclic nucleotides in rat pinealocytes.
Constance L. Chik,Anthony K. Ho +1 more
Journal ArticleDOI
α1D L-Type Ca2+-Channel Currents: Inhibition by a β-Adrenergic Agonist and Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) in Rat Pinealocytes
Constance L. Chik,Qin Yue Liu,Bing Li,David C. Klein,Mark J. Zylka,Dong Sun Kim,Hemin Chin,Edward Karpinski,Anthony K. Ho +8 more
TL;DR: Results indicate that pinealocytes express predominantly α1D L‐channels, and the β‐adrenergic agonist isoproterenol and PACAP inhibit the L‐channel currents through elevation of cyclic AMP, however, an α‐ adrenergic‐mediated mechanism also appears to be involved in the effect of norepinephrine on the L-channel currents.
References
More filters
Journal ArticleDOI
A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
TL;DR: This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr with little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose.
Journal ArticleDOI
Changes in the levels of inositol phosphates after agonist-dependent hydrolysis of membrane phosphoinositides.
TL;DR: The results suggest that the earliest event in the stimulus-response pathway is the hydrolysis of polyphosphoinositides by a phosphodiesterase to yield inositol 1,4,5-trisphosphate and inositl 1, 4-bisph phosphate, which are subsequently hydrolysed to inositoli 1-phosphates and inposol.
Journal ArticleDOI
Role of guanine nucleotide binding protein in the activation of polyphosphoinositide phosphodiesterase.
TL;DR: Evidence that mast cell secretion is inhibited by internalized neomycin, a compound known to interact with PPI, and the PPI phosphodiesterase of human neutrophil plasma membranes can be activated simply by adding GTP analogues in the presence of concentrations of Ca2+ that pertain in unstimulated cells are provided.