Suppression of plasminogen activator production in sheep embryos in vitro after treatment with cycloheximide or ouabain.

Effects of the metabolic inhibitors cycloheximide and ouabain on development in vitro and plasminogen activator production by sheep embryos were investigated. Embryos (n = 152) from the eight-cell to the morula stage were surgically collected from naturally mated, oestrus-synchronized and superovulated Polypay ewes. In Expt 1, embryos (n = 104) were grouped by cell stage, cultured in Whitten's medium with 1.5% BSA containing 0, 0.1 or 1.0 microgram cycloheximide ml-1 for 24 h, washed and cultured in this medium for 168 h. In Expt 2, morulae (n = 48) were cultured for 48 h in Whitten's medium with 1.5% BSA transferred to the same medium containing 0 or 1.0 mmol ouabain l-1 and cultured for 24 h, and then washed and cultured in this medium for 120 h. At 24 h intervals in both experiments, the medium was recovered and analysed for plasminogen activator. In Expt 1, eight-cell embryos underwent limited development; little difference in the production of plasminogen activator due to cycloheximide treatment was therefore observed. Compared with medium without cycloheximide, treatment with 1.0 microgram cycloheximide ml-1 reduced the number of 16-cell embryos (P < 0.05) and morulae (P < 0.05) (60% versus 10% and 77% versus 8%, respectively) that began to hatch. The mean production of plasminogen activator was greatest in embryos cultured initially as morulae compared with that of 16-cell and eight-cell embryos (P < 0.05). Cycloheximide treatment suppressed the mean production of plasminogen activator in a dose-dependent manner (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)