Seasonal changes of antidiuretic hormone action on sodium transport across frog skin.

HONG, SUK KI, CHUN SIK PARK, YANG SAENG PARK, AND JIN KYUNG KIM. Seasonal changes of antidiuretic hormone action on sodium transport acruss frog skin. Am. J. Physiol. 215(2) : 439-443. 1968.-The stimulating effect of antidiuretic hormone (ADH) on Na transport across isolated frog skin (Runa temporuriu) was studied monthly, along with the glycogen contents of liver and muscle. ADH induced a sustained marked increase in short-circuit current (SCC) during the cold seasons, while it induced a transient slight rise in SCC during the warm seasons. Moreover, the glycogen content of the liver and muscle was markedly greater during the cold season than during the warm season. However, blood glucose and plasma free fatty acid levels showed no clear seasonal variations. When the inside bathing solution was fortified with certain substrates such as glucose, pyruvate, acetate, or P-hydroxybutyrate, the SCC increased significantly in summer frogs but not in winter frogs. Intermediates of TCA cycle were without effect in both seasons. Moreover, summer frogs which are refractory to ADH became responsive to this hormone when the inside bathing solution was fortified with pyruvate or P-hydroxybutyrate but not with other substrates. However, winter frogs responded to ADH similarly both in presence and absence of substrates. On the basis of these findings, it was postulated tentatively that the characteristic seasonal changes in the stimulating effect of ADH on Na transport across frog skin are primarily attributable to corresponding changes in the substrate content of the skin.