Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4347676 | Neuroscience Letters | 2008 | 5 Pages |
Abstract
Using an immortalized adrenal chromaffin cell line (MAH cells), we investigated the cellular mechanisms underlying sensitivity to glucose-free solution (aglycemia) using ratiometric Ca2+ imaging and whole-cell recording. Though few cells (<15%) responded to aglycemia with an increase in intracellular-free Ca2+ concentration ([Ca2+]i), in most cells (â¼75%), aglycemia caused >50% suppression of the Î[Ca2+]i induced by the depolarizing stimulus, high (10Â mM) K+. Moreover, in normal K+, the average aglycemia-induced rise in Cai2+ as well as the proportion of aglycemia-responsive cells increased in the presence of the KATP channel blocker, glibenclamide. During membrane potential (Vm) measurements, aglycemia induced either hyperpolarization (6/20), depolarization (4/20) or no change in Vm. RT-PCR and Western blotting confirmed the presence of KATP channel subunits Kir6.2 and SUR1 in MAH cells. These findings suggest a dual inhibitory and excitatory action of aglycemia in MAH cells, where activation of KATP channels effectively inhibits or blunts the Î[Ca2+]i due to the excitatory effect. Thus, this cell line appears as an attractive model for studying the molecular mechanisms of glucosensing.
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Authors
Nikol A. Piskuric, Stephen T. Brown, Min Zhang, Colin A. Nurse,