Publications of Faculty of Medicine:The Role Of Angiotensin ri Receptors In Uterine Reactivity Of Pregnant Rats: Abstract

Title:
The Role Of Angiotensin ri Receptors In Uterine Reactivity Of Pregnant Rats
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Abstract:

In this study we evaluated the role of angiotensin H (Ang H) receptors in the spontaneous contractility of isolated myometrial strips from pregnant rat uterus. A total number of 24 pregnant albino rats (in the last part of gestation) were used. The animals were divided into four groups and we determined the changes in the tone, frequency, and amplitude of contractions of isolated myometrial strips in each group after administration of (1) Ang ri in a dose of 5, 10,20 rig/m1 (group 1), (2) Ang I1+ATI receptor antagonist (Losartan) in a dose of 5 ng Ang 11+100 nmol Losartan/yd. 10 ng Mg 11+100 nmol Losartan1/24 and 20 ng Ang 11+100 nmol Losartan (group 2), (3) Losartan in a dose of 1, 10, 100 nmol/,.J (group 3) and (4) angiotensin 11 converting enzyme inhibitor (Captopril in a dose of 5,10,20 pmol ) (group 4). The results of this study demonstrated that Ang 11 induced a significant concentration dependent increase in both tone and rhythmic oscillations of the uterine smooth muscles. In addition, the small dose of Mg 11 increased the amplitude of uterine contraction, while the other two large doses caused a concomitant decrease in it. This effect was significantly reduced by ATI receptor antagonist (Losartan). In addition, the ATI receptor antagonist (Losartan) when administered alone to the uterine strips caused a significant concentration dependent decrease in the contractility and rhythmic oscillations of the uterine smooth muscles. The study revealed also that angiotensin converting enzyme inhibitor (Captopril ) caused a significant dose dependent decrease in the frequency and amplitude of uterine contraction. However, Captopril produced insignificant changes in the uterine tone. We can conclude that angiotensin H receptors are present in the uterine tissues and that angiotensin H seems to be formed locally by renin and angiotensin converting enzyme in this tissues. This is in accordance with a functional renin angiotensin system which may be important for contraction of the myometrial smooth muscle cells.

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