[Characteristics of the electrophysiological parameters of the embryonic cell membranes in the loach during Na+, K+-ATPase inhibition]. / Kharakteristiki élektrofiziologicheskikh parametrov membran émbrional'nykh kletok v'iuna pri ingibirovanii Na+, K+-ATFazy.

Influence of ouabain on changes in transmembrane potential (TMP) and the membrane conductance has been studied in developing embryos of the loach Misgurnus fossilis L. Ouabain does not cause any significant changes in TMP level within 10-15 min after treatment but the membrane was then depolarized to a degree depending on developmental stage. Exposure to ouabain increases the conductance and changes the selectivity of membranes. Reversion potential of ionic current is then decreased from -70- -100 to -5- -30 mV. It is supposed that gradual membrane depolarization owing to the decrease of K+ gradient favors the membrane conductance changes under the influence of ouabain. It has been established that the active transport of Na+ and K+ takes part in realization of the rhythm of TMP level periodical oscillations during synchronous cleavage division.

[Influence of adrenaline on the transmembrane potential changes in developing loach embryos]. / Vliianie adrenalina na dinamiku transmembrannogo petentsiala razvivaiushchikhsia zarodyshei v'iuna.

Changes of transmembrane potential (TMP) in loach embryos developing for 7--8 hours in the medium supplemented with different adrenalin concentrations and in its mixtures with insulin or actinomycin D are studied. It was shown that value and mode of TMP changes, and its depolarizing effect and removal of periodic TMP oscillations in particular, which coincided with normal cycles of synchronous blastomere divisions depended on adrenalin level in the medium. Actinomycin D gradually eliminated the adrenalin influence on embryos only in the second half of the above mentioned period of their development, whereas insulin exerted its effect already at the early stages of embryogenesis.