Caribbean maitotoxin elevates [Ca2+]i and activates non-selective cation channels in HIT-T15 cells

AIM:To investigate the cytotoxic mechanism of caribbean maitotoxin(MTX-C) in mammalian cells.METHODS:We used whole-cell patch-clamp techniques and fluorescence calcium imaging to determine the cellular toxic mechanisms of MTX-C in insulin secreting HIT-T15 cells,which is a system where the effects o...

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Published inWorld journal of diabetes Vol. 4; no. 3; pp. 70 - 75
Main Authors Lu, Xin-Zhong, Deckey, Robert, Jiao, Guo-Liang, Ren, Hui-Feng, Li, Ming
Format Journal Article
LanguageEnglish
Published United States Baishideng Publishing Group Co., Limited 15.06.2013
Subjects
Brief
Ca2
Calcium
cell
cells
channels
clamp
fluorescence
gated
High
Insulin
Maitotoxin
patch
secreting
voltage
Whole
High voltage gated Ca2+ channels
Insulin secreting cells
Whole cell patch clamp
Maitotoxin
Calcium fluorescence
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Summary:AIM:To investigate the cytotoxic mechanism of caribbean maitotoxin(MTX-C) in mammalian cells.METHODS:We used whole-cell patch-clamp techniques and fluorescence calcium imaging to determine the cellular toxic mechanisms of MTX-C in insulin secreting HIT-T15 cells,which is a system where the effects of MTX have been observed.HIT-T15 cells stably express L-type calcium current,making it a suitable model for this study.Using the fluorescence calcium indicator Indo-1 AM,we found that there is a profound increase in HIT-T15 intracellular free calcium 3 min after application of 200 nmol/L MTX-C.RESULTS:About 3 min after perfusion of MTX-C,a gradual increase in free calcium concentration was observed.This elevation was sustained throughout the entire recording period.Application of MTX-C did not elicit the L-type calcium current,but large cationiccurrents appeared after applying MTX-C to the extracellular solution.The current-voltage relationship of the cation current is approximately linear within the voltage range from-60 to 50 mV,but flattened at voltages at-80 and-100 mV.These results indicate that MTX-C induces a non-voltage activated,inward current under normal physiological conditions,which by itself or through a secondary mechanism results in a large amount of cationic influx.The biophysical mechanism of MTX-C is different to its isoform,pacific maitotoxin(MTX-P),when the extracellular calcium is removed.CONCLUSION:We conclude that MTX-C causes the opening of non-selective,non-voltage-activated ion channels,which elevates level of intracellular calcium concentration and leads to cellular toxicities.
Bibliography:Xin-Zhong Lu,Department of Pharmacology,University of South Alabama,Mobile,AL 36688,United States Robert Deckey,Food and Drug Administration of United States,Mobile,AL 36609,United States Guo-Liang Jiao,Hui-Feng Ren,Convelscent Hospital,Xingcheng 125100,Liaoning Province,China Ming Li,Department of Physiology,Tulane University,New Orleans,LA 70112,United States
Correspondence to: Dr. Ming Li, Department of Physiology, Tulane University, Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, United States. mli@tulane.edu
Telephone: +1-504-9888207 Fax: +1-504-9882675
Author contributions: Lu XZ performed the majority of experiments; Deckey R, Jiao GL and Ren HF provided vital reagents and analytical tools and were also involved in editing the manuscript; Li M designed the study and wrote the manuscript.
ISSN:1948-9358
1948-9358
DOI:10.4239/wjd.v4.i3.70