Upregulation of bradykinin B1-receptor expression after myocardial infarction

To determine the influence of the myocardial infarction (MI) on bradykinin B1-receptor (B1R) regulation, we studied its expression in the left ventricle (LV) after MI. Rats were submitted to a permanent occlusion of the left coronary artery. Six hours, 24 h and 6 days after MI or after sham operation, left ventricular pressure (LVP) and dP/dt(max) were measured. LV-total RNA was extracted and BIR expression was analysed by a RNase-protection assay teach group n = 6). LVP and dP/ dt(max) were impaired at all time points after MI. Basal BIR expression was not detectable in controls. Six hours after MI, the B1R expression was upregulated and reached a maximum 24 h after MI (4 fold vs 6 h). Six days post-MI, BIR expression returned to levels found 6 h after MI. These data are the first demonstration for an induced myocardial B1R expression in an in vivo model of MI.