Table. Effect of sildenafil citrate on mating behavior of Tgfb1 null mutant micea
 
  Tgfb1+/+
  Tgfb1+/+ (sildenafilb)
  Tgfb1-/-
  Tgfb1-/- (sildenafilb)
  % time spent in anogenital investigationc   27 (18-44)   24 (23-32)   37 (15-48)   41 (31-48)
  Mounts   5/5   3/3   4/6   3/5
  Latency, min   7 (4-48)   10 (3-30)   10 (2-44)   10 (2-22)
  No. of mounts   7 (1-13)   3 (1-3)   48 (27-68)d   2 (2-62)
  Duration, sec   3 (3-6)   4 (3-4)   3 (3-3)   3 (2-4)
  Intromissions   5/5   3/3   2/6   0/5
  Latency, min   51 (4-53)   43 (18-59)   9, 11   NA
  No. of intromissions   9 (3-13)   22 (1-27)   3, 6d   NA
  Duration, sec   12 (11-18)   11 (11-15)   5, 6   NA
  Ejaculation   5/5   3/3   0/5   0/5
  Latency, min   63 (32-85)   76 (46-90)   NA   NA
  Duration, sec   33 (23-44)   38 (32-43)   NA   NA
  Total no. of mounts   11 (10-27)   26 (5-29)   51 (27-71)d   2 (2-51)
  Mounts/mine
  0.39 (0.19-0.59)
  0.44 (0.12-0.44)
  0.47 (0.39-0.75)
  0.05 (0.02-0.45)

  Abbreviations: NA, behavior not observed in any mice; Tgfb1, transforming growth factor β1.
  a Data are median (range), except when <3 mice displayed the behavior, in which case the values for each mouse are displayed. Data were analyzed by Mann-Whitney U test.
  b Mice received sildenafil citrate 400 ng/g (IP) 30 min prior to introduction of a receptive female.
  c Behavior of male mice was observed for 2 hours under red light. Percent of time in the first 10 min spent in anogenital investigation of the female was calculated.
  d P < .05 compared with Tgfb1+/+ control group.
  e The total number of mounts (including mounts, intromissions, and ejaculation) was calculated and divided by the interval between the first and last mount to determine the number of mounts per minute.