Effects of in vitro hypoxia on depolarization-stimulated accumulation of inositol phosphates in synaptosomes.
The effects of potassium and in vitro histotoxic hypoxia (i.e. KCN) on phosphatidylinositol turnover in rat cortical synaptosomes were determined. [2-3H] Inositol prelabelled rat synaptosomes were prepared from cerebral cortex slices that had been incubated with [2-3H] inositol. Depolarization with 60 mM KCl increased [2-3H] inositol phosphates in a time dependent manner. Depolarization with 60 mM KCl increased [2-3H] inositol trisphosphate transiently at 5 s. K+ induced rapid formation of [2-3H]-inositol bisphosphate and maintained an elevated level for at least 5 min. K+ stimulated gradual formation of [2-3H] inositol monophosphate with time. One minute of hypoxia enhanced potassium-stimulated [2-3H] inositol bisphosphate formation. However, 30 min of hypoxia impaired potassium-stimulated accumulation of [2-3H] inositol phosphates. The effects of histotoxic hypoxia were all dependent upon calcium in the medium and on K+-depolarization. Thus, hypoxia altered the K+-induced accumulation of inositol phosphates in prelabelled synaptosomes in a time dependent, biphasic manner that was calcium dependent.
Huang
H M
HM
Cornell University Medical College, Burke Rehabilitation Center, White Plains, NY 10605.
Gibson
G E
GE
D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects*; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D002855:Chromatography, Thin Layer; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D008297:Male; D010716:Phosphatidylinositols / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011190:Potassium Cyanide / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D010743:Phospholipids; D011190:Potassium Cyanide; D011188:Potassium; D002118:Calcium