Energetic cooperation via ion-permeable junctions in mixed animal cell cultures

AbstractLow ouabain concentration (1 × 10−4 M) is shown to decrease intracellular K+ (K+in) and to increase intracellular Na+ (Na+in) in human fibroblast cell cultures. The same ouabain concentration was without effect upon K+in ad Na+in in rodent cultures such as BHK-21, mouse fibroblasts and rat glyoma C6 cells. K+in and Na+in in the mixed cultures of human and BHK-21 fibroblasts or human and mouse fibroblasts were found to be resistant to 1 × 10−4 M ouabain whereas that of the mixtures of human and rat glyoma C6 cells proved to be ouabain-sensitive. The gap-junction-mediated dye transfer was revealed between human and BHK-21 cells. Such an effect was very small in the human-C6 cell mixed culture. It is concluded that cells with active ion pumps can support the maintenance of K+ and Na+ gradients in cells with inactive pumps, provided that effective ion transport via gap junctions takes place

Use of picosecond infrared laser for micromanipulation of early mammalian embryos

A high repetition rate (80 MHz) picosecond pulse (approximately 2 psec) infrared laser was used for the inactivation (functional enucleation) of oocytes and two-cell mouse embryos and also for the fusion of blastomeres of two-cell mouse embryos. The laser inactivation of both blastomeres of two-cell mouse embryos by irradiation of nucleoli completely blocked further development of the embryo. The inactivation of one blastomere, however, did not affect the ability of the second intact blastomere to develop into a blastocyst after treatment. Laser inactivation of oocytes at Metaphase II (MII) stage and parthenogenetically activated pronuclear oocytes also completely blocked their ability for further development. Suitable doses of irradiation in cytoplasm region did not affect the ability of embryos and activated oocytes to development. The efficiency of laser induced fusion for blastomeres of two-cell embryos was 66.7% and all the tetraploid embryos developed successfully into blastocysts in culture. Our results demonstrate unique opportunities of the applications of a suitable infrared periodic pulse laser as a universal microsurgery tool for individual living cells