新生鼠窒息后心肌基质金属蛋白酶活性与心肌损害的相关性

目的探讨新生鼠窒息后心肌组织心肌基质金属蛋白酶（MMPs）表达与心肌损害的相关性。方法60只7—10日龄Wistar鼠,随机分成对照组（D组）、窒息组（A、B、C3组,分别为窒息复氧后1、7、14d）,每组15只。窒息组模拟新生鼠常压窒息模型,测定cTnI水平;心肌组织MMPs-3、9活性;心肌病理积分及胶原含量。结果cTnI（ng／m1）A组（0．3680±0．40）明显高于D组（0．0783±0．06）P〈0．05,B组下降（0．1889-i-0．15）P仍〈0．05,C组降至正常（0．1338±0．07）P〉0．05;心肌组织MMPs-3活性A组（0．1847±0．04）,B组最高（O．2780±0．05）,C组（0．2014±0．05）,与D组（0．1213±0．03）比较P均〈0．05;MMPs-9活性A、B、C组逐渐增高（0．1502±0．01、0．1715±0．01、0．1868±0．03、P均〈0．05）;心肌胶原含量A、B、C组逐渐增高（35．59±1．09、38．94±0．67、40．69±0．75ng／ml分别为P〉0．05、P〈0．05、P〈0．05）;MMPs-3、9表达与心肌病理积分呈正相关（r分别为0．669、0．667,P均〈0．05）,与胶原含量呈正相关（r分别为0．482、0．679,P均〈0．05）。结论新生鼠窒息后心肌MMPs-3、9过度激活,继发胶原含量增高,MMPs-3、9活性与心肌病理损害密切相关。提示MMPs参与了窒息后心肌损害,可能是心肌间质重塑的因素之一。

Correlation between matrix metalloproteinases activities and myocardial injury in neonatal rats after asphyxia

OBJECTIVE: To study possible correlation between matrix metalloproteinases (MMPs) activities and myocardial injury after asphyxia in neonatal Wistar rats. METHOD: Sixty neonatal Wistar rats (7 to 10 days old) were randomly divided into four groups: control group (group D); asphyxia groups A, B and C (1 day, 7 days, 14 days after asphyxia), every group had 15 rats. In the asphyxia groups, animal model was produced by normobaric asphyxia. Groups A, B and C were sacrificed on days 1, 7 and 14 days after asphyxia, and group D rats were sacrificed on the 7 th day. Then the heart blood was taken to tested the serum cTnI. The myocardial MMPs-3 and 9 activity was measured by using immunohistochemical assay. Histological sections of the hearts were stained with hematoxylin-eosin and myocardial histopathological scores were determined under an optical microscope. The amount of myocardial collagen was measured by means of chloramines T. RESULTS: cTnI was significantly higher in group A (0.3680 +/- 0.40 ng/ml) than group D (0.0783 +/- 0.06 ng/ml) (P < 0.05), and was lower in group B (0.1889 +/- 0.15 ng/ml) but still significantly different from that of group D (P < 0.05), and declined to the normal level in group C (0.1338 +/- 0.07 ng/ml), but the difference between groups C and D was not significant (P > 0.05). Myocardial tissue MMPs-3 activity was transiently high in group A (0.1847 +/- 0.04), higher in group B (0.2780 +/- 0.05) as compared to group D (0.1213 +/- 0.03) (P < 0.05 for all). The activity of MMPs-3 increased earlier than that of MMPs-9. The amount of myocardial collagen of group B (38.94 +/- 0.67) and C (40.69 +/- 0.75) was significantly greater than that of group D (P < 0.05). Myoardial tissue MMPs-3 and MMPs-9 positively correlated with myocardial histopathological scores (r = 0.669, 0.667, P < 0.05) and myocardial collagen (r = 0.482, 0.679, P < 0.05). CONCLUSIONS: In rats with asphyxia, there was an excess activation of myocardial MMPs-3 and MMPs-9 activities and secondary to which, the quantity of myocardial collagen increased. The injuries of myocardium may be closely associated with myocardial tissue MMPs. MMPs may be used to evaluate the severity of myocardial interstitial damage.