Journal
BIOCHEMICAL PHARMACOLOGY
Volume 66, Issue 12, Pages 2409-2411Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.bcp.2003.08.024
Keywords
NCX; NCKX; CGP-37157; KB-R7943; mitochondria; neurons
Categories
Funding
- NINDS NIH HHS [R29 NS037390, NS 37390] Funding Source: Medline
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In the heart, 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4, 1-benzothiazepin-2(3H)-one (CGP-37157) inhibits mitochondrial but not sarcolemmal Na+/Ca2+ exchange. Therefore, CGP-37157 is often used as an experimental tool to study the role of mitochondrial Na+/Ca2+ exchange in Ca2+ homeostasis in various cells, including neurons. However, neurons express several K+-dependent (NCKX) and/or K+-independent (NCX) isoforms of plasmalemmal Na+/Ca2+ exchange not expressed in the sarcolemma. Because it has never been determined whether CGP-37157 inhibits plasmalemmal NCKX and/or NCX isoforms in neurons, we tested this possibility. As an index of NCKX and/or NCX activity, we studied Na-dependent and gramicidin-induced Ca-45(2+) accumulation in the presence and absence of K+, respectively. In primary cultures of cerebellar granule cells, CGP-37157 with IC50 of 13 muM inhibited over 70% of plasmalemmal NCX activity (P < 0.01) but not NCKX activity. Our data suggest that the effects of CGP-37157 on neuronal Ca2+ homeostasis include inhibition of certain plasmalemmal NCX isoform(s). Because cerebellar granule cells robustly express NCX3 transcripts, which are not expressed in the heart, it appears that this isoform may be CGP-37157 sensitive. (C) 2003 Elsevier Inc. All rights reserved.
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