[Influence of pregnancy on the vascular response to norepinephrine and serotonin in rat carotid artery].
Because the frequency of migrainous attacks tends to decrease in late pregnancy, we speculated that the responsiveness of the cerebral arteries to vasoactive amines which are associated with migraine changes during pregnancy. We therefore measured the effect of norepinephrine and serotonin on isometric contractions of the isolated carotid arterial rings in pregnant (n = 18) and nonpregnant rats (n = 18). The response of the arterial rings to norepinephrine was decreased significantly in the pregnant rat (p < 0.02) compared with the nonpregnant rat. This refractoriness to norepinephrine in the pregnant rat exists in both the following conditions: indomethacin (5 x 10(-7) mol/L), an inhibitor of production of prostaglandin, added to the reacting solution, and endothelium was removed. There was no difference in the maximal contraction tension in each condition. We did not observe any difference in the response to serotonin in the pregnant rat carotid artery compared with the nonpregnant one. In order to assess the activity of the endothelium-derived relaxing factor, we then measured the dilating response to acetylcholine in precontracted carotid arterial ring with 10(-7) mol/L norepinephrine. There was no difference in the dilating response. These finding indicated that the refractoriness of pregnant rat carotid artery to norepinephrine was not induced by endothelial factors, such as prostaglandin, or by an endothelium-derived relaxing factor.
Ikeda
T
T
Department of Obstetrics and Gynecology, Miyazaki Medical College.
Ikenoue
T
T
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002339:Carotid Arteries / Q000187:drug effects*; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology*
D012701:Serotonin; D000109:Acetylcholine; D009638:Norepinephrine; D007213:Indomethacin