Initiation of the cortical reaction in hamster and sheep oocytes in response to inositol trisphosphate.
Microinjection of inositol 1,4,5-triphosphate into sheep and hamster oocytes induces secretion of cortical granules in a dose-dependent manner. In the sheep, this effect is strongly pH-dependent with minimal exocytosis taking place at pH 6.8 but a full cortical reaction occurring at pH8.0. Exocytosis in the hamster is also affected by the pH of the external medium but to a lesser extent. Injection of GTP gamma S also induces exocytosis in both species but is more effective in the hamster. It is suggested that inositol metabolism stimulated by sperm-egg interaction with a GTP-binding protein may be part of the mechanism leading to cortical granule exocytosis and that this may be modulated by the external pH.
Cran
D G
DG
AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
Moor
R M
RM
Irvine
R F
RF
D000818:Animals; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis / Q000187:drug effects*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D008647:Mesocricetus; D008854:Microscopy, Electron; D009865:Oocytes / Q000187:drug effects* / Q000648:ultrastructure; D012756:Sheep; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate