Intravaginal Administration of Sildenafil Citrate Increases Blood Flow in the Bovine Uterus

The aim of the study was to evaluate the influence of sildenafil citrate administrated intravaginaly on the blood flow in the bovine uterus during dioestrus. Uterine blood flow was examined in six healthy adult cows. Sildenafil was administrated intravaginaly to each co w between the 6^th and 8^th d of the ovarian cycle, in the form of vaginal suppositories containing 100 mg of active substance at a dose of 100, 200, or 300 mg per animal. Uterine perfusion was estimated by the colour Doppler examination, and obtained results were analysed with the Pixel Flux Software (Chameleon, Germany). Moreover, cardiovascular parameters were also evaluated. Animals were examined before and five times after drug application (two times at 15 min intervals, and three times at 2 h intervals). A placebo suppository was also given to the cows. The analysis of the intensity and velocity of blood flow in the uterus proved that sildenafil administrated intravaginaly significantly increased blood flow in the uterus and the effect of increased perfusion was observed for 4 h and 30 min after administration. The effect of increased uterine perfusion was observed after low as well as high doses of sildenafil. Significant changes in the cardio-vascular parameters were not detected. There were no changes in the uterine perfusion as well as in cardiovascular parameters after placebo administration.