Fig. 2

Comparison of baseline urinary levels of aquaporin-2 (u-AQP2) in the cold (November-March) and warm seasons (April–October), expressed as protein to-urinary creatinine ratio (u-AQP2/uCre, fmol/mg). Urinary AQP2 excretion was measured in the urine samples by ELISA as previously described [10]. a u-AQP2 excretion was significantly higher in the warm season respect to the cold season in all participants, **p < 0.01, n = 52. b In males, u-AQP2 excretion was significantly higher in the warm season respect to the cold season, ****p < 0.0001, n = 24. c In females, u-AQP2 excretion was significantly higher in the warm season respect to the cold season, *p < 0.05, n = 28. Values are expressed as means ± S.E. Student’s t-test was used for the statistical analysis