Meeting Abstract
P1.116 Sunday, Jan. 4 Evidence for increased protein catabolism as a result of water-restriction in House sparrows. GERSON, A.R.*; GUGLIELMO, C.G.; University of Western Ontario, Canada agerson2@uwo.ca
During migration, non-stop flights are fuelled exclusively by endogenous energy stores and pose a significant physiological challenge, especially when considering fuel and water management. Long distance migrants mobilize a fuel mixture consisting of up to 90% lipid and 10% protein. Although many theories have been proposed, the role of protein catabolism in endurance exercise remains unclear. The catabolism of lipids yields little metabolic water (0.029 g H2O kJ-1) relative to protein catabolism (0.155 g H2O kJ-1). Thus, it has been proposed that protein may be metabolized as a source of water during long distance flights under dehydrating conditions. Protein is catabolized directly from muscles and organs, which may have consequences to flight performance and stopover refueling efficiency. Thus, the goal of this study was to investigate the possible affect of water restriction on fuel use during rest and simulated endurance exercise (shivering) in house sparrows (Passer domesticus ). Magnetic resonance body composition analysis was used to measure changes in body composition (fat and lean mass) through an 18 hr water restriction followed by a 4 hr shivering trial. Blood samples were taken before and after the shivering trial for the determination of plasma osmolality and plasma metabolite analysis. Flow through respirometry was used to measure metabolic rate and total evaporative water loss before and during shivering. Water restriction resulted in significantly greater lean mass loss relative to control birds, elevated plasma uric acid levels, and higher plasma osmolality. These data provide preliminary evidence supporting the hypothesis that negative water balance may result in increased protein catabolism, possibly as a strategy to offset high rates of evaporative water loss.
