Journal article
Vasocative Intestinal Peptide Increases Intracellular Calcium in Astroglia: Synergism with α-Adrenergic Receptors
Proceedings of the National Academy of Sciences - PNAS, Vol.91(6), pp.2036-2040
15 Mar 1994
Abstract
In type I astrocytes from rat cerebral cortex, vasoactive intestinal peptide (VIP) at concentrations below 1 nM evoked an increase in intracellular calcium ion concentration. This response, however, was observed in only 18% of the astrocytes examined. α-Adrenergic stimulation with phenylephrine or norepinephrine also resulted in an intracellular calcium response in these cells and the threshold sensitivity of astrocytes to phenylephrine was vastly different from cell to cell. Treatment of these astrocytes with VIP (0.1 nM) together with phenylephrine at subthreshold concentrations produced large increases in intracellular Ca2+concentration ([Ca2+]i) and oscillations. The continued occupation of the α-adrenergic receptor was required for sustained synergism. Both α-receptor stimulation and stimulation with the mixture of agonists induced the cellular calcium response by triggering release of calcium from cellular stores, since the response persisted in the absence of extracellular calcium. Furthermore, thapsigargin pretreatment, which depletes intracellular stores, abolished the agonist-induced [Ca2+]iresponse. VIP (0.1 nM) and phenylephrine were found to increase cellular levels of inositol phosphates; however, there was no apparent additivity in this response when the agonists were added together. These observations suggest a calcium-mediated second messenger system for the high-affinity VIP receptor in astrocytes and that α-adrenergic receptors act synergistically with the VIP receptor to augment an intracellular calcium signal. The synergism between diverse receptor types may constitute an important mode of cellular signaling in astroglia.
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Details
- Title
- Vasocative Intestinal Peptide Increases Intracellular Calcium in Astroglia: Synergism with α-Adrenergic Receptors
- Creators
- Alessandro FatatisLynne A. HoltzclawRina AvidorDouglas E. BrennemanJames T. Russell
- Publication Details
- Proceedings of the National Academy of Sciences - PNAS, Vol.91(6), pp.2036-2040
- Publisher
- National Academy of Sciences of the United States of America
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- College of Medicine; Pharmacology and Physiology; Drexel University
- Identifiers
- 991020111096504721