Vascular adaptations to pregnancy in mice: effects on myogenic tone.
The mechanisms underlying vascular adaptations in pregnancy remain to be fully elucidated. One of the contributory mechanisms for reduced vascular tone may be a reduction of myogenic tone. Myogenic tone was assessed as the difference between internal diameter in the presence and absence of external calcium at different intramural pressure steps (60-100 mmHg). Myogenic responses were reduced in resistance-sized mesenteric and main uterine arteries in late pregnant compared with nonpregnant C57BL/6J mice. In vessels from pregnant, but not nonpregnant mice, the myogenic response was enhanced by preincubation with nitric oxide (NO) synthase inhibitor N(G)-nitro-l-arginine methyl ester, was further elevated by the gap junction inhibitor 18-alpha glycyrrhetinic acid, but was unaltered by the prostaglandin H synthase inhibitor meclofenamate. Endothelium removal enhanced myogenic tone only in the vessels from pregnant animals, thus confirming the role of the endothelium in modulating myogenic tone in pregnancy. These results suggest that endothelium-derived NO as well as gap junction communications modulate myogenic tone in mouse pregnancy.
Veerareddy
Sukrutha
S
Perinatal Research Centre, University of Alberta, Edmonton, Canada.
Cooke
Christy-Lynn M
CL
Baker
Philip N
PN
Davidge
Sandra T
ST
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002450:Cell Communication / Q000502:physiology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D008643:Mesentery / Q000098:blood supply; D051379:Mice; D008810:Mice, Inbred C57BL; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014654:Vascular Patency / Q000502:physiology
D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase