Meeting Abstract
To complete their annual migrations, birds may fly over vast ecological barriers. While the primary fuel for migratory flight is fat, birds also catabolize lean mass from muscle and organs, including the kidney. It is unknown whether reductions in kidney mass that occur during flight result in decreased kidney function or damage. Creatinine and inulin are commonly used to measure kidney function, and neutrophil gelatinase-associated lipocalin (NGAL) is a protein biomarker of kidney damage in mammals that has never been studied in birds. To evaluate kidney damage and function, I measured plasma creatinine as an endogenous marker of GFR, FITC-inulin as an exogenous marker of GFR, and NGAL of Yellow-rumped Warblers before, immediately after, and 24h after flight or rest in a wind tunnel. Birds flew or rested in dry or humid conditions, which has been previously shown to alter the rate of protein breakdown in flight. NGAL levels were below detection and therefore a poor biomarker for kidney damage. Creatinine concentrations significantly increased in the 24-hour recovery rest and flight birds, and in dry conditions, indicating reduced filtration. However, inulin-measured filtration tended to be higher in dry conditions for both flight and rest birds. This study suggests that fasting and flight may impact kidney function, particularly in dry conditions. These endogenous and exogenous markers did not clearly indicate kidney damage, but future research will use molecular markers to quantify kidney atrophy and damage.
