CAFFEINE AND NICOTINE - EFFECTS ON HUMAN PLACENTAL VASCULAR TONE IN-VITRO

Objective: To investigate if the adverse effects caffeine and nicotine have on the fetus are mediated by placental vascular tone alterations . Study Design: Isolated human placental arteries and veins at resting tone in the presence and absence of endothelium were exposed to cumul ative doses of caffeine (0.1 nM-0.1 mM), nicotine, and cotinine (1.0 n M-1.0 mM). Some of the vessels were submaximally precontracted with U4 4619 prior to exposure to cumulative doses of the drugs. Dose-response curves to serotonin, KCl, U46619, and prostaglandin F-2 alpha were al so obtained in the presence or absence of caffeine, nicotine, and coti nine (0.1 mM). Results: Caffeine did not alter vascular tone in human placental arteries and veins at resting tone (n = 10). Modest relaxati ons (15-30% of maximal tone) were noted with the addition of the drug to precontracted placental blood vessels. Similarly, nicotine and coti nine had no effect on resting tone in placental blood vessels, whereas small relaxations (6-10% of maximal tone) occurred in vessels precont racted with U46619 (n = 7-10). Additionally caffeine (n = 6-10), nicot ine, and cotinine failed to alter the dose-response curves to other co ntractile agents (n = 7-10). Conclusions: Based on these results caffe ine, nicotine, and the nicotine metabolite cotinine do not appear to a lter human placental vascular tone in vitro. These results suggest tha t the adverse effects of these drugs on the fetus during pregnancy are unlikely to be due to changes in placental vascular tone.