Activation of porcine oocytes using cyclopiazonic acid, an inhibitor of calcium-dependent ATPases.
Cyclopiazonic acid (CPA), a potent inhibitor of endogenous calcium-dependent ATPases, is able to induce parthenogenetic activation in pig oocytes matured in vitro. Sixty-four percent of matured pig eggs cultured with 100 nM CPA for 4 hr were activated. A similar activation rate was observed in oocytes treated with thapsigargin, another inhibitor of calcium-dependent ATPases. The parthenogenetic development of CPA-activated eggs did not proceed beyond the 8-cell stage. The blockage of calcium channels by verapamil only slightly decreased the proportion of CPA-activated pig oocytes. This indicates that the release of calcium from intracellular stores is sufficient for oocyte activation and calcium influx from extracellular sources has no significant role. The significant decrease in CPA-activated oocytes (100 nM of CPA for 4 hr) after a microinjection of heparin indicated that the mobilization of intracellular calcium stores is mediated through inositol trisphosphate receptors. On the other hand, the only slightly depressed activation rate in oocytes microinjected with ruthenium red and procaine indicates that CPA mobilizes a much smaller amount of calcium through the ryanodine receptors. The marked inhibitory effect of ophiobolin A and W7 on the activation of CPA-treated pig oocytes suggests that the calcium signal, as the second messenger, acts downstream through calmodulin. J. Exp. Zool. 287:304-315, 2000.
Petr
J
J
Research Institute of Animal Production, Department of Biology of Reproduction, 104 01 Prague 10-Uhrínĕves, Czech Republic. petr@novell.vuzv.cz
Rozinek
J
J
Jílek
F
F
Urbánková
D
D
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006493:Heparin / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008845:Microinjections; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D010312:Parthenogenesis / Q000187:drug effects* / Q000502:physiology; D011343:Procaine / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000378:metabolism; D012430:Ruthenium Red / Q000494:pharmacology; D054830:Sesterterpenes; D013449:Sulfonamides / Q000494:pharmacology; D013552:Swine / Q000502:physiology*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D007211:Indoles; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D054830:Sesterterpenes; D013449:Sulfonamides; D013729:Terpenes; D012430:Ruthenium Red; C040764:ophiobolin A; D011343:Procaine; C017967:W 7; D019284:Thapsigargin; D006493:Heparin; D014700:Verapamil; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid