Changes in cell biochemistry in response to culture of protoplasts with oxygenated perfluorocarbon.

Superoxide dismutase (superoxide oxidoreductase; EC 1.15.1.1; SOD) was measured in enzymatically isolated protoplasts of Salpiglossis sinuata following culture in aqueous nutrient medium overlaying oxygen-gassed perfluorodecalin (Flutec PP6; BNFL Fluorochemicals, UK). SOD was extracted from harvested, lysed protoplast-derived cells after 1, 3, 7 and 14 days of culture and assayed spectrophotometrically. Protoplasts cultured with oxygenated PFC (+/- s.e.m, n = 5) showed significant increases in mean SOD activity to 4.2 +/- 0.1 U after 1 day (P < 0.05) and 9.3 +/- 0.7 U after 3 days (P < 0.01), with a fall in mean SOD after 7 days (5.1 +/- 0.9 U), similar to control. The decrease in SOD after 7 days correlated closely with a progressive fall in pO2 in the PFC phase over the same period. In contrast, control protoplasts (medium alone) or protoplasts cultured in medium overlaying non-oxygenated PFC showed no significant changes in mean SOD activity over the 14-day culture assessment period.