Meeting Abstract
Amphibians are able to osmoregulate through their skin, and hormones can modulate these processes. In anuran amphibians, prolactin typically increases ion movement across the skin. However, the specific ions and mechanisms vary by species. We hypothesize that part of this variation can be explained by differences in life history traits, specifically the amount of time the adults of different species spend submerged in water. Unlike most anuran amphibians, African clawed frogs, Xenopus laevis, are fully aquatic even during the adult stage of their lifecycle. Thus, we investigated the effects of prolactin on ion transport in X. laevis by measuring short circuit current across isolated skin samples. Prolactin increased short circuit current in a dose-dependent fashion. Prolactin increases apical to basolateral sodium transport across the skin. The effect on key transporters, such as the epithelial sodium channel (ENaC) and the Na+ /K+ pump, were investigated using nystatin permeabilization and protein inhibitors (ex. amiloride and ouabain). Further, the transient nature of the prolactin-induced current suggested a role for intracellular calcium. To delineate the role of intracellular vs. extracellular calcium, experiments were conducted in calcium-free buffer and chelating intracellular calcium using BAPTA. Future experiments will measure intracellular calcium concentration in response to prolactin using spectrofluorometry and the calcium sensitive fluorescent probe FURA-2AM.
