Human chorionic gonadotropin attenuates the vascular response to angiotensin II.
OBJECTIVE
Our purpose was to investigate interactions between human chorionic gonadotropin (hCG) and angiotensin II (ANG II) in resistance arteries.


METHODS
Isolated pre-arteriolar vessels of female Sprague-Dawley rats were prepared from the mesenteric arcade and the mesometrium. Dose-response curves were recorded by means of an video-electronic arteriograph system.


RESULTS
(1) hCG dilated mesenteric (MA; EC(50): 21+/-6.9 mU/ml) and uterine (UA; EC(50): 256+/-44.3 mU/ml)) resistance arteries pre-constricted with ANG II. In the presence of glybenclamide (1 micromol/l), the response of MA was reduced by >50%. (2) After application of hCG for 1h, vasoconstriction by ANG II was significantly attenuated in MA. This effect was dose-dependent and was not observed in UA. Efficacy of ANG II could be restored, when hCG was followed by glybenclamide.


CONCLUSIONS
hCG may contribute to the reduction in arterial tone seen early in human pregnancy. Its vascular effects are in part mediated by the activation of adenosine 5'-triphosphate-sensitive potassium channels, suggesting a protein kinase A dependent signaling pathway.
Hermsteiner
Markus
M
Department of Obstetrics and Gynecology, Justus Liebig University, Klinikstrasse 32, D-35392 Giessen, Germany. markus.hermsteiner@gyn.med.uni-giessen.de
Zoltan
Dorina R
DR
Künzel
Wolfgang
W
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000187:drug effects; D001808:Blood Vessels / Q000187:drug effects*; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014599:Uterus / Q000098:blood supply; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D006063:Chorionic Gonadotropin; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000804:Angiotensin II; D000255:Adenosine Triphosphate; D005905:Glyburide