Premium
Secretagogue‐evoked changes in intracellular free magnesium concentrations in rat pancreatic acinar cells.
Author(s) -
Lennard R,
Singh J
Publication year - 1991
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1991.sp018520
Subject(s) - secretagogue , intracellular , magnesium , endocrinology , medicine , chemistry , biophysics , microbiology and biotechnology , biology , stimulation , biochemistry , organic chemistry
1. This study employs the fluorescent dye Mag‐Fura‐2 acetoxymethyl ester (AM) to measure intracellular free magnesium concentration [Mg2+]i in isolated rat pancreatic acinar cells. Initially a number of protocols were investigated to develop optimal loading conditions for the dye Mag‐Fura‐2 AM. The procedure yielding cells which showed minimal dye loss and no adverse compartmentalization was adopted for subsequent experiments. 2. The mean resting [Mg2+]i is 1.39 +/‐ 0.08 mM (n = 39). 3. Acetylcholine (ACh), cholescystokinin‐octapeptide (CCK8), carbamylcholine chloride evoked marked reduction in [Mg2+]i in pancreatic acinar cells compared to resting values in the absence of secretagogues. The ACh‐evoked decrease in [Mg2+]i was abolished by pre‐treatment with atropine. In contrast, noradrenaline, adrenaline and histamine had no significant effect on [Mg2+]i. 4. In acinar cells loaded with the Ca(2+)‐sensitive dye, Fura‐2 acetoxymethyl ester (AM), ACh stimulation resulted in a marked elevation in intracellular free Ca2+ concentration [Ca2+]i. This response was blocked by pre‐treatment with atropine. 5. Atomic absorption spectrophotometry was used to measure Mg2+ levels in effluent samples from pancreatic segments. Stimulation of pancreatic segments with ACh resulted in a marked elevation in Mg2+ concentrations (net efflux). On removal of ACh, Mg2+ concentration returned to resting level followed by a small net influx of Mg2+ into pancreatic tissue. 6. The results demonstrate that secretagogue‐evoked alteration in [Mg2+]i may occur concurrently with Mg2+ release from pancreatic tissue.