A comparison of myogenic and endothelial properties of myometrial and omental resistance vessels in late pregnancy

• Published in: American journal of obstetrics and gynecology 1997-03, Vol.176 (3), p.560-566
• Main Authors: Kublickiene, Karolina-Rasa, Kublickas, Marius, Lindblom, Bo, Lunell, Nils-Olov, Nisell, Henry
• Format: Article
• Language: English
• Subjects: acetylcholine; Acetylcholine - pharmacology; Biological and medical sciences; Female; Fundamental and applied biological sciences. Psychology; Humans; Labor, Obstetric; Medicin och hälsovetenskap; Mother. Fetoplacental unit. Mammary gland. Milk; myogenic; Myometrium - blood supply; nitric oxide; Nitric Oxide Synthase - antagonists & inhibitors; Omentum - blood supply; Pregnancy; Pregnancy Trimester, Third; Pregnancy. Parturition. Lactation; Pressure; resistance arteries; Vascular Resistance - drug effects; Vertebrates: reproduction
• ISSN: 0002-9378; 1097-6868
• DOI: 10.1016/S0002-9378(97)70548-9

OBJECTIVE: Our purpose was to compare myometrial and omental resistance arteries from term pregnant women with respect to myogenic behavior in the presence or absence of a nitric oxide synthase inhibitor and to compare distensibility and acetylcholine-mediated dilatation in these vessels. STUDY DESIGN: Intramyometrial ( n = 17) and omental ( n = 14) resistance arteries from term normal pregnant women were studied in a pressurized arteriograph system. Myogenic tone was evaluated during increments in intraluminal pressure from 20 to 120 mm Hg with and without inhibition of nitric oxide synthase. Endothelium-dependent relaxation was assessed by evaluating the response to acetylcholine (10 –6 mol/L) in arteries pressurized at 70 mm Hg. RESULTS: Myogenic tone was greater at all pressure steps in the myometrial than in the omental arteries ( p < 0.05). Inhibition of nitric oxide synthase with N ω-nitro- l-arginine had no influence on myogenic tone in either group. Relaxation to acetylcholine was greater in myometrial (18% ± 4%) compared with omental vessels (7% ± 2%, p < 0.05). The passive distensibility (Ca ++-free solution and in the presence of papaverine) of arteries from the myometrium and the omentum was similar. CONCLUSION: Normal pregnancy is associated with different mechanical properties of resistance vessels from the two vascular beds studied. Basal nitric oxide release does not modify myogenic tone, at least under no-flow conditions. Acetylcholine-induced relaxation is greater in myometrial than in omental arteries. (Am J Obstet Gynecol 1997;176:560-6