Changes of type Ⅰ and type m collagen in atrium myocardium of children with ventricular septal defect

Zhenping XU; Zhikun GUO; Peili HAN; Hongjun XI

ABSTRACT

BACKGROUND:

Type Ⅰ and type Ⅲ collagen, the main components of cardiac stroma,have supporting,protective and restrictive effects on myocardial cells. They are essential for the heart to maintain its normal shape and function.

OBJECTIVE:

To explore the effects of types Ⅰ and Ⅲ collagen on cardiac function by observing their changes in atrium myocardium of children with ventricular septal defect (VSD).

DESIGN:

A case analysis. SETTTING Department of Cytobiology, Xinxiang Medical College.

PARTICIPANTS:

Six children who had died from accidents were selected from the Pediatric Department of the First Affiliated Hospital,Xinxiang Medical College, between January and August 2003. Informed consent was obtained form their relatives. They were 4 males and 2 females,ranging from 1 to 15 years in age. Congenital heart diseases were excluded by naked-eye anatomical examination,and right atrium tissues were collected for the study. Meanwhile, 21 children with VSD, 12 males and 9 females aged 1-17 years,were recruited from the Department of Cardiac-thoracic Surgery of the same hospital.

METHODS:

A small amount of fresh myocardium was cut from the right atrium at the edge of incision. Peroxidase-labeled strepto-avidin immunohistochemical method was adopted to detect the expression of types Ⅰ and Ⅲ collagen protein in atrium myocardium, which was analyzed using image analysis to calculate the area composition ratio of type Ⅰ and type Ⅲ collagen in atrium myocardium(representing the relative area percentage of collagen protein) and area percentage (representingthe expression percentage of collagen protein). MAIN OUTCOME

MEASURES:

Expression of typeⅠand type Ⅲ collagen protein in atrium myocardium.

RESULTS:

Six normal controls and 21 patients with VSD entered the final statistical analysis. ① Type Ⅰcollagen of normal atrium was strip-like fibers with different diameters connected with each other,whereas type Ⅲ collagen was scattered in spots and pieces. ② The distribution of type Ⅰ and Ⅲ collagen of atrium in VSD patients was mostly similar to that of the normal controls; only part of them displayed extreme rearrangement, that is,type Ⅰcollagen presenting large-speckle increment,breakage or disappearance, while type Ⅲ collagen increased in stripes and bundles. ③ The area percentage and area composition ratio of type Ⅰ and type Ⅲ collagentype Ⅰ collagen expressed more than type Ⅲ collagen in normal myocardium [area percentage (48.82±12.35)％ vs (40.02±13.53)％, t=2.173, P ＜ 0.05;area composition (15.87±6.03) μm2 vs (13.62 6.94) μm2, t=2.221, P ＜ 0.05].Likewise, type Ⅰ collagen expressed more highly than type Ⅲ collagen in VSD myocardium [area percentage (55.37±10.42)％ vs (50.27±14.36) ％,t=2.173, P ＜ 0.05; area composition (24.93±9.62) μm2 vs (19.22 12.03) μm2,t=2.221, P＜ 0.05]. The content of both type Ⅰ and type Ⅲ collagen in VSD children was obviously higher than that in normal children(t=2.153-2.234,P ＜ 0.05).

CONCLUSION:

In children with VSD, part of type Ⅰ and type Ⅲ collagen is found rearranged and increased in atrium, which may result from the interstitial compensation due to cardiac dysfunction.