Matrix metalloproteinase-9 and tensile strength of fetal membranes in uncomplicated labor.
OBJECTIVE
To analyze the relation between tensile strength and levels of matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and tissue inhibitor of metalloproteinase-2 at a number of sites in human fetal membranes.


METHODS
Tensile strengths of fetal membranes from five women who delivered vaginally at term were measured by the method of modified force application. A piece of membrane at each measured site was then dissected, and the levels of matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and tissue inhibitor of metalloproteinase-2 were measured by sandwich enzyme immunoassay. The relationship between tensile strength and enzyme levels was evaluated by Scheffé F test at a total of 81 sites on the five membranes.


RESULTS
The mean tensile strength of the membranes was 45.3 +/- 19.8 (mean +/- standard deviation) mmHg/0.3 mm(2) (n = 81). When the measured sites were divided according to tensile strength into four groups (<25, 25-49, 50-74, and >/=75 mmHg/0.3 mm(2)), the level of matrix metalloproteinase-9 (0.72 +/- 0.82 nmol/g protein, n = 12) in the less than 25 mmHg/0.3 mm(2) group was significantly higher than the other groups (0.35 +/- 0.22, 0.28 +/- 0.15, and 0.15 +/- 0.08 nmol/g protein; n = 39, 23, and 7, respectively). The significance level was still higher when the molar ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1 was used for comparison.


CONCLUSIONS
An increased molar ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1 might be related to decreased tensile strength of human fetal membranes in uncomplicated labor.
Uchide
K
K
Department of Obstetrics and Gynecology, School of Medicine, School of Medicine, Kanazawa University, 13-1, Kanazawa, 920-8641, Takara-machi, Japan. k-uchide@med.kanazawa-u.ac.jp
Ueno
H
H
Inoue
M
M
Sakai
A
A
Fujimoto
N
N
Okada
Y
Y
D005321:Extraembryonic Membranes / Q000502:physiology*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007743:Labor, Obstetric / Q000502:physiology*; D020781:Matrix Metalloproteinase 1 / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000032:analysis* / Q000502:physiology; D011247:Pregnancy; D013718:Tensile Strength
D020780:Matrix Metalloproteinase 9; D020781:Matrix Metalloproteinase 1