Urinary profile and baseline levels of NO reaction products. Panel A:- Effect of CYP on micturition pattern. Cumulative urine volume was measured over the period of 12 daylight hours before and after CYP injection (150 mg/kg) in male and female rats. In absence of CYP, female rats (empty black dot) voided a cumulative volume of 5.88 ± 1.88 ml compared to slightly higher volume of 7.67 ± 0.59 ml in male rats (empty black triangle). The mean urinary frequency was 7.8 ± 0.54 in female rats and 7.57 ± 0.86 in male rats during the 12-h time period at baseline. The cumulative urine volume increased significantly to 9.65 ± 2.34 ml in female (solid black dot) and to 12.9 ± 1.03 ml in male rats (solid black triangle) after CYP, relative to baseline values in female rats (ANOVA, Tukey post hoc test; *p < 0.05). The mean urinary frequency also increased significantly after CYP to 19 ± 1.5 and 20.25 ± 2.6 in males and females, respectively. Panel B - Urine levels of NO reaction products at baseline and after CYP. NO2-/NO3- are expressed as μmol/mg creatinine. The measurement of NO2-/NO3- in individual urine voids from control male rats showed that levels of NO reaction products do not remain constant throughout the day, but are maximal at the beginning of day and then stabilize for the remainder of the day. Values at baseline in female rats (empty black dot) did not change over the course of the day. The levels of NO products in urine of CYP treated female rats (solid black dot) were significantly higher compared to male rats at baseline (empty black triangle) and after CYP injection (solid black triangle) (ANOVA, Tukey post hoc test; *p < 0.01).