Effects of nicotine on uterine blood flow and intrauterine oxygen tension in the rat.

Subcutaneous injection of nicotine (0.5 or 5 mg/kg body wt) resulted in a marked and prolonged reduction in uterine blood flow and intrauterine oxygen tension in pseudopregnant rats. By 10 min after nicotine administration (5 mg/kg) uterine perfusion was reduced by 40%, remained suppressed for 90 min and returned to the pre-treatment level by 120 min. Rats receiving the 0.5 mg nicotine/kg also showed a marked reduction in uterine blood flow, although the response was slower in onset and longer in duration. Nicotine (5 mg/kg) also resulted in a sustained decrease in intrauterine oxygen tension from a control value of 48.9 +/- 3.6 to 22.2 +/- 2.6 mmHg at 45--60 min and 21.7 +/- 1.5 mmHg at 60--90 min. The frequency and amplitude of fluctuations in intrauterine oxygen tension were still reduced by 90 min after treatment.