Differential expression of alpha 1, alpha 3 and alpha 5 integrin subunits in acute and chronic stages of myocardial infarction in rats.
OBJECTIVE
Anchoring cardiac myocytes to extracellular matrix, which is mediated mainly by integrins on their surfaces, is important for maintaining the architecture of myocardial tissues and transmitting mechanical force. We evaluated the expression of alpha integrin subunits on myocytes and the accumulation of interstitial collagen and fibronectin at acute and chronic stages after myocardial infarction.


METHODS
Myocardial infarction was induced by ligation of left coronary arteries in rats. The expression of alpha 1, alpha 3 and alpha 5 integrin subunits, and accumulation of collagen and fibronectin were analyzed with immunohistochemistry or sirius-red staining.


RESULTS
In hearts without infarction, moderate expression of the alpha 3 subunit and only slight expression of the alpha 5 subunit were observed on myocytes. In the first week after infarction, the alpha 1 subunit, collagen and fibronectin were increased only in the peri-infarcted area, while the alpha 5 subunit was increased both in peri-infarcted and non-infarcted areas. At day 42, the expression of the alpha 1 subunit and collagen were still increased, although the alpha 5 subunit and fibronectin were decreased. The expression of the alpha 3 subunit was not altered throughout the experimental period.


CONCLUSIONS
These data suggest that integrin subunits play an important role in healing and remodeling processes after myocardial infarction.
Nawata
J
J
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Ohno
I
I
Isoyama
S
S
Suzuki
J
J
Miura
S
S
Ikeda
J
J
Shirato
K
K
D000818:Animals; D015703:Antigens, CD / Q000032:analysis / Q000378:metabolism*; D002448:Cell Adhesion; D002908:Chronic Disease; D003094:Collagen / Q000032:analysis / Q000378:metabolism; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D005353:Fibronectins / Q000032:analysis / Q000378:metabolism; D007150:Immunohistochemistry; D039423:Integrin alpha1; D039422:Integrin alpha3; D039482:Integrin alpha5; D016023:Integrins / Q000032:analysis / Q000378:metabolism*; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism*; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D015703:Antigens, CD; D005353:Fibronectins; D039423:Integrin alpha1; D039422:Integrin alpha3; D039482:Integrin alpha5; D016023:Integrins; D003094:Collagen