Upregulation of the cardiac bradykinin B2 receptors after myocardial infarction.
An increase in myocardial bradykinin (BK) might be a mechanism to protect the heart during acute myocardial infarction (MI). To characterize the regulation of the myocardial B2 receptor during MI, we studied the expression of this BK receptor in the right ventricle (RV), left ventricle (LV) and myocardial septum (S) 24 h after left coronary ligation. Experiments were performed in male Wistar Kyoto rats (n = 10) and compared with sham operated animals (n = 6). After total RNA extraction, the myocardial B2-receptor expression was analyzed by a RNase protection assay (n = 6), using a specific probe from the coding region of the receptor gene. After 24 h, rats with MI were normotensive and showed an impaired left ventricular function. The B2-receptor expression of the LV of these rats was significantly elevated (2.3-fold) compared to sham operated rats. Furthermore, we found a dramatic upregulation of the B2 receptor in the RV (7.8-fold) and a dramatic expression of B2 receptor mRNA in S of infarcted hearts, whereas in the S of sham operated rats no B2 receptor expression could be detected. Our data show clearly that the described increase in BK during myocardial ischemia is accompanied by an elevated B2-receptor expression in the infarcted and non-infarcted parts of cardiac ventricles.
Tschöpe
C
C
Department of Cardiology and Pneumology, University Hospital Benjamin Franklin, Free University of Berlin, Germany. tsch@zedat.fu-berlin.de
Koch
M
M
Spillmann
F
F
Heringer-Walther
S
S
Mochmann
H C
HC
Stauss
H
H
Bader
M
M
Unger
T
T
Schultheiss
H P
HP
Walther
T
T
D000818:Animals; D001794:Blood Pressure; D006339:Heart Rate; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism* / Q000503:physiopathology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000096:biosynthesis*; D015854:Up-Regulation; D016277:Ventricular Function, Left
D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin