Table 1.

Effect of HWI on urine volume and osmolality and urinary AVPa

GenotypeTreatmentnWater Intake (mL)Urine Volume (mL)Urine Osmolarity (mOsmol/kg H2O)Urinary AVP (pg/mg creatinine)
Male
    PCKCONT818 ± 118 ± 21088 ± 96257 ± 22
    PCKHWI1068 ± 5b58 ± 5b232 ± 47b114 ± 46b
    +/+CONT810 ± 59 ± 11498 ± 130160 ± 19
    +/+HWI894 ± 26c91 ± 10b197 ± 73b88 ± 38
Female
    PCKCONT1018 ± 316 ± 2982 ± 74435 ± 83
    PCKHWI863 ± 9b49 ± 8b284 ± 52b111 ± 59b
    +/+CONT713 ± 512 ± 11559 ± 211335 ± 49
    +/+HWI10107 ± 10b80 ± 11b131 ± 25b31 ± 4b
  • a Addition of 5% glucose to drinking water increased water intake 3.5-fold in PCK rats and 8.2-fold in normal Sprague-Dawley (+/+) rats (composites of male and female rats). Rats drink more water that contained glucose because they have a preference for sweet fluid (33). Urine volume increased accordingly. High water intake (HWI) decreased urine osmolalities below 290 mOsmol/kg H2O. Urinary arginine vasopressin (AVP), an indicator of plasma AVP levels, decreased significantly in both PCK and +/+ rats with HWI. Statistical differences between HWI and control (CONT) rats (either +/+ or PCK) were determined by one-way ANOVA.

  • b P < 0.01.

  • c P < 0.05.