The effects of triaminopyrimidine on the short circuit current and transmembrane potentials of the isolated rat visceral yolk sac in vitro.
Intracellular potentials in the cells from 17.5-day old rat visceral yolk sacs were measured by a glass microelectrode. When penetrated from the maternal side, the cells have potentials of about 50.2 +/- 1.9 mV (inside negative) which were reduced by increasing the external K+ concentration and increased by removing Na+ ions from the bathing fluid. Triaminopyrimidine (TAP) which inhibited Na+ transport caused a dose-dependent depolarization of the cell membrane. The depolarization was dependent on the presence of extracellular Ca2+ ions. It is proposed that TAP may inhibit Na+ transport by increasing the intracellular concentration of calcium ions.
D000818:Animals; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism; D011247:Pregnancy; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D015017:Yolk Sac / Q000187:drug effects / Q000502:physiology*
D011743:Pyrimidines; C012070:2,4,6-triaminopyrimidine; D011188:Potassium