Sodium and chloride transport in tadpoles of the bullfrog Rana catesbeiana.

ALVARADO, RONALD H., AND ANNE MOODY. Sodium and chloride transport in tadpoles of the bullfrog Rana catesbeiana. Am. J. Physiol. 218(5): %1510-1516. 1970.-Unfed bullfrog tadpoles actively transport sodium and chloride ions into their body fluids from a dilute bath. The rate of exchange is about 1 pmole/lO g-hr for each ion. This can be enhanced by salt depletion. Sodium and chloride can be transported independently each in exchange for an endogenous ion of like charge. Before stage XXII the body fluids are negative to the bath (1 mu NaCl) by 5-10 mv. At stage XXII and thereafter, the body fluids are positive. This correlates with the appearance of a potential difference and the active transport of sodium across the isolated skin. The electrical resistance of the skin also increased markedly at stage XXII. Tadpoles drink the medium at a rate of 0.14 ml/l0 g-hr and absorb about half of the fluid ingested. However the gut probably does not play a major role in sodium and chloride balance. Sodium and chloride are actively transported from fluid perfused through the gill chambers. This transport is enhanced by salt depletion.