Hypoxia evokes catecholamine secretion from rat pheochromocytoma PC-12 cells.
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| Abstract |
We have monitored exocytosis of catecholamines from individual PC-12 cells by amperometry using carbon fiber microelectrodes in order to investigate possible secretory responses to acute hypoxia. In normoxia, no secretion was detected from cells perfused with a solution containing 5 mM K+. However, when [K+] was raised (10-100 mM), exocytotic events were observed. Hypoxia (PO2 11 mmHg) stimulated secretion from PC-12 cells, and in hypoxic conditions exocytosis was greater at each [K+] studied as compared with normoxia. Hypoxia-evoked secretion was abolished in Ca2+ free solutions containing 1 mM EGTA and by the non-specific Ca2+ channel blocker, Cd2+ (200 microM). Secretion was also largely inhibited by omega-conotoxin GVIA (1 microM). Exocytosis was also observed in normoxia when cells were exposed to tetraethylammonium (1-10 mM), but not 4-aminopyridine (3 mM). Our findings indicate that hypoxia evokes exocytosis via depolarization arising from inhibition of a TEA-sensitive K+ conductance, leading to Ca2+ influx primarily via N-type Ca2+ channels.
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| Authors | S C Taylor, C Peers |
| Journal | Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 248 Issue 1 Pg. 13-7 (Jul 09 1998) ISSN: 0006-291X [Print] United States |
| PMID | 9675077 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't) |
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