Differences of Angiotensin Ⅱ receptor expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions

Abstract:

OBJECTIVE: It has been shown that angiotensin converting enzyme inhibitors (ACEI) can reduce the ratio of pulmonary and systemic circulation blood flow (Qp/Qs) and thus decrease the blood flow of left-to-right shunt in children with left-to-right shunt congenital cardiac lesions. This suggests that there are differences in the expression of Angiotensin Ⅱ receptors between systemic and pulmonary circulation. This study aimed to explore the differences of Angiotensin Ⅱ receptors type 1 and type 2 (AT1 and AT2 receptors) expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions. METHODS: Lung and skeletal muscular tissues were obtained from 20 children with left-to-right shunt congenital cardiac lesions by biopsy during operation. The specimens were stained by immunohistochemistry techniques for AT1 and AT2 receptors. The technique of morphometric analysis was used to measure the immunoreactivity of AT1 and AT2 receptors (expressed by IOD values) of pulmonary, skeletal muscular and pleural small vascular wall the diameter of which was 15-100 μm. RESULTS: The immunoreactivities of AT1 and AT2 receptors of pulmonary small vascular walls [(124±95)×103 and (85±62)×103 respectively] were significantly lower than those of skeletal muscular [(219±156)×103 and (155±139)×103 respectively] and those of pleural small vascular walls [(279±191)×103 and (175±128)×103 respectively] in children with left-to-right shunt congenital cardiac lesions (P<0.05). CONCLUSIONS: The expression of AT1 and AT2 receptors in small vascular walls of systemic circulation was higher than that of pulmonary circulation in children with left-to-right shunt congenital cardiac lesions.