Mitotic synchrony in mammalian cells treated with nitrous oxide at high pressure.

Mammalian cells grown in suspension or monolayer cultures were synchronized for cell division by the application of nitrous oxide under pressure. The metaphase block induced by nitrous oxide was dependent on pressure and was reversible. Exposure of HeLa cells to nitrous oxide had no significant effect on the synthesis of DNA, RNA, or protein. The progress of cells through the mitotic cycle was also unaffected. A high degree of mitotic synchrony was obtained in suspension cultures of HeLa cells treated with thymidine during exponential growth, resuspended in fresh medium, and then exposed to nitrous oxide.