OBJECTIVETo assess the effects of rhBNP on left ventricular (LV) remodeling in rats with acute myocardial infarction (AMI).

METHODSAMI was induced by ligating coronary artery in male Sprague Dawley rats. Two days after surgery, AMI rats received intravenous infusion of rhBNP (15 microg/kg or 5 microg/kg once daily, n = 15 each) or saline (placebo control, n = 15) through Jugular Vein. Sham-operated rats (n = 15) served as normal control. Four weeks later, hemodynamic measurements were performed, left ventricular weight (LVW), ratio of left ventricular weight to body weight (LVW/BW), left ventricular diameter (LVD) and infarct size were determined. Plasma angiotensin II and myocardial angiotensin II levels were also measured.

RESULTSCompared with sham-operated rats, LVW, LVW/BW, LVD and myocardial angiotensin II level were significantly increased, while the LV systolic pressure (LVSP), +/- dp/dt were significantly reduced in saline treated AMI rats (all P < 0.05). LVW/BW, MI size, LVD and myocardial angiotensin II in rhBNP treated AMI rats were significantly lower [LVW: (492.6 +/- 34.0) mg, (498.8 +/- 47.8) mg, (570.0 +/- 24.2) mg, P < 0.01; LVW/BW: 2.0 +/- 0.2, 2.0 +/- 0.2, 2.3 +/- 0.1, P < 0.01; LVD: (25.3 +/- 2.9)%, (31.4 +/- 3.0)%, (46.4 +/- 3.0)%, P < 0.01; myocardial angiotensin II: (881.3 +/- 62.7) pg/L, (1186.0 +/- 94.5) pg/L, (2436.7 +/- 280.3) pg/L, P < 0.05], while LVSP and +/- dp/dt in rhBNP treatment groups were significantly increased than saline treated AMI rats (P < 0.05 or P < 0.01).

CONCLUSIONRhBNP is effective in attenuating left ventricular remodeling after AMI in rats.