Embryonic development of spontaneous motility in chick embryos. Identification of participation of NMDA-mechanism by magnesium ions.
The influence of magnesium ions on the spontaneous motility and its development was studied in chick embryos aged from day 4 to day 19 of incubation. 1-An acute application of MgCl2 (80 mg/kg e.w.) evoked from day 13 of incubation a significant depression of spontaneous motility together with decreased synchronization of embryonic spontaneous movements. 2-The resting spontaneous motility in 17-day-old embryos after chronic continual application of MgCl2 (11.5 +/- 1.21 mg/kg e.w./24 h.) from day 4 to day 12 (Mg2+/ser.C) was reduced and exhibited smaller synchronization of spontaneous movements by the preponderance of movements with moderate amplitude. 3-The chronic application of MgCl2 expressed itself also by the changed reactivity of spontaneous motility to the factors influencing NMDA- and NO-ergic mechanisms. The decrease of NMDA activatory effect, the weakened depressory effect of ketamine, the reduction of periodic depressive effect of arcaine and the reduction of activatory effect of cocktail (NMDA + L-arginine) took place. 4-The investigated effects of Mg2+ confirm the participation of NMDA-ergic mechanism and simultaneously point out the possible role of NO-ergic mechanism in the genesis and the development of spontaneous motility in chick embryos.
Sedlácek
J
J
Institute of Physiology, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
D000818:Animals; D002642:Chick Embryo / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D007649:Ketamine / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology*; D009068:Movement / Q000187:drug effects; D016202:N-Methylaspartate / Q000494:pharmacology*
D018691:Excitatory Amino Acid Antagonists; D015636:Magnesium Chloride; D016202:N-Methylaspartate; D007649:Ketamine