The antagonism between Ca and Na ions on the frog's heart.
D000818:Animals; D001001:Anura; D002118:Calcium / Q000494:pharmacology*; D000013:Congenital Abnormalities / Q000187:drug effects*; D006321:Heart; D007477:Ions; D011898:Ranidae; D012964:Sodium / Q000494:pharmacology*
D007477:Ions; D012964:Sodium; D002118:Calcium
CALCIUM/effects; DEFECTS, CONGENITAL/effect of drugs on; SODIUM/effects