Meeting Abstract

P1.116  Monday, Jan. 4  Comparison of water potential in two anuran species, Anaxyrus boreas and Pseudacris sierra LEMENAGER, L.A.*; TRACY, C.R.; MALONEY, N.; University of Nevada, Reno; University of Nevada, Reno; University of Nevada, Reno lemen22@hotmail.com

Experiments were performed to determine the ability of western toads (Anaxyrus boreas) and pacific tree frogs (Pseudacris sierra) to obtain water from sucrose solutions differing in osmotic potential. A standard body mass was measured as the mass of a hydrated frog with an empty bladder. The frogs were dehydrated to 90% of their standard body mass and experimentally rehydrated in a series of varying sucrose solutions. The data were used to estimate (by regression) the water exchange rate for each frog in each solution. The means and standard deviations of these rates were plotted against the water potential of the sucrose solutions to find the x-intercept of the resulting plot, which represents the conditions at which no water is exchanged, and thus, the water potential of the frog. The water potential of A. boreas and P. sierra were similar to water potentials of their blood under the experimental conditions, so it appears that control of whole-animal water potential is not different from osmotic potential of blood under the conditions of this experiment.