[A preliminary study on the hormonal causes of seasonal change in miniature endplate potentials at the neuromuscular junctions of the toad].
The hormonal causes of seasonal change in amplitudes of miniature endplate potentials (MEPP) in the adult toad (Bufo bufo gargarizans) were studied with intracellular recordings of MEPP at the neuromuscular junction of sartorius muscle fiber in vitro by adding L-thyroxine sodium and estrone to the bath medium during spring and autumn respectively. The results showed that L-thyroxine sodium (50 mumol/ L) could not change the amplitude of MEPP, regardless of spring or autumn, but estrone (100 mumol/L) could cause a clear increase in MEPP amplitude in both seasons. From these results it was presumed that thyroxine might be less related to the seasonal changes in MEPP amplitude whereas the seasonal fluctuations of gonadal hormones in the body might play a role.
Jing
H
H
Yang
S
S
Lü
G
G
D000818:Animals; D002023:Bufo bufo; D004970:Estrone / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000502:physiology; D009469:Neuromuscular Junction / Q000502:physiology*; D010507:Periodicity; D012621:Seasons; D013974:Thyroxine / Q000494:pharmacology*
D004970:Estrone; D013974:Thyroxine