Molecular mechanism of magnesium transport in epithelial cells
type: CreativeWork
description: Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitters released by the autonomic nervous system. The hormones and neurotransmitters (secretagogues) utilise different intracellular mediators to elicit enzyme and fluid secretion. One particular mediator is the second messenger calcium (Ca2+) and there is now much evidence that the abundant divalent cation magnesium (Mg 25 may play an important physiological role in regulating the mobilisation of cellular Ca 2t Thus, the present study was designed to investigate (a) the effect of a modification of extracellular Mg2 on secretagogue-evoked enzyme and hydrochloric acid (HCI) secretion and Ca 2 homeostasis in the pancreatic acinar cells and parietal cells and (b) to characterise the molecular mechanism of Mg 2 transport using fluorimetric and spectroscopic studies. The results have shown that application of either cholecystokinin-octapeptide (CCK-8) or acetylcholine (ACh) to rat pancreatic segments can result in marked increases in amylase and trypsinogen output in normal (1.1 mlvi) extracellular magnesium [Mg 2 0. When [Mg2 0 was elevated to 10 mlvi, there was a significant (P C 0.05) decrease in secretagogue-evoked pancreatic enzyme secretion. On the other hand, in low (0 mM) [Mg2 0 both CCK-8 and ACh elicited marked increases in enzyme secretion similar to the responses obtained in the presence of normal [Mg 2 o . The effects closely correlate with the concurrent reductions and increases in intracellular free calcium concentrations 2 +-. [Ca j ifrom studies performed with fljra-2-AM loaded pancreatic acmi dunng perturbation of [Mg2 0 These findings indicate that Mg 24 can influence enzyme secretion by regulating Ca24 mobilisation. The possible site of action of Mg2 in controlling Ca24 appears to be at the level of Ca 24 influx, since experiments, using thapsigargin or ionomycin, agents which release Ca2+ from intracellular Ca2+ stores, were not affected by a variation in [Mg 2…
abstract: Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitters released by the autonomic nervous system. The hormones and neurotransmitters (secretagogues) utilise different intracellular mediators to elicit enzyme and fluid secretion. One particular mediator is the second messenger calcium (Ca2+) and there is now much evidence that the abundant divalent cation magnesium (Mg 25 may play an important physiological role in regulating the mobilisation of cellular Ca 2t Thus, the present study was designed to investigate (a) the effect of a modification of extracellular Mg2 on secretagogue-evoked enzyme and hydrochloric acid (HCI) secretion and Ca 2 homeostasis in the pancreatic acinar cells and parietal cells and (b) to characterise the molecular mechanism of Mg 2 transport using fluorimetric and spectroscopic studies. The results have shown that application of either cholecystokinin-octapeptide (CCK-8) or acetylcholine (ACh) to rat pancreatic segments can result in marked increases in amylase and trypsinogen output in normal (1.1 mlvi) extracellular magnesium [Mg 2 0. When [Mg2 0 was elevated to 10 mlvi, there was a significant (P C 0.05) decrease in secretagogue-evoked pancreatic enzyme secretion. On the other hand, in low (0 mM) [Mg2 0 both CCK-8 and ACh elicited marked increases in enzyme secretion similar to the responses obtained in the presence of normal [Mg 2 o . The effects closely correlate with the concurrent reductions and increases in intracellular free calcium concentrations 2 +-. [Ca j ifrom studies performed with fljra-2-AM loaded pancreatic acmi dunng perturbation of [Mg2 0 These findings indicate that Mg 24 can influence enzyme secretion by regulating Ca24 mobilisation. The possible site of action of Mg2 in controlling Ca24 appears to be at the level of Ca 24 influx, since experiments, using thapsigargin or ionomycin, agents which release Ca2+ from intracellular Ca2+ stores, were not affected by a variation in [Mg 2…
author: Geada, Maria do Rosario Moreno Cruz Colaco
language: en
keywords: C130 - Cell biology
date published: 1998-01
date modified: 2026-07-24T01:36:10Z
provider: University of Central Lancashire
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Central Lancashire