Effects of neuropeptide Y and noradrenaline on uterine artery blood pressure and blood flow velocity in the pregnant guinea-pig.

Neuropeptide Y (NPY) coexists with noradrenaline (NA) in many peripheral sympathetic nerves. Since it has been found that patients with preeclampsia have elevated myometrial levels of both NPY and NA, we have examined the effects of NPY and NA on blood pressure and blood flow velocity in the uterine artery of the term pregnant guinea-pig (n = 7). We found that NPY (10-1000 pmol) significantly increased local blood pressure, with increases ranging from 15.4% (P less than 0.05) to 46.4% (P less than 0.001) as compared to control. NA (10-1000 pmol) had similar effects, increasing local blood pressure (5%-57.5% (P less than 0.01]. NPY had no significant effect on uterine blood flow velocity as measured by pulsed Doppler ultrasound, whereas NA (10-1000 pmol) decreased local uterine blood flow velocity (5.9%-30.2% (P less than 0.05]. The effect of NPY on blood pressure was phentolamine-resistant, indicating that it is not alpha-adrenoceptor-mediated. The results indicate that NPY and NA have significant pressor effects in the local uterine circulation during pregnancy in the guinea-pig.