Myocardial Infarction Increases Cardiac Interstitial Fluid Vasopressor and Inflammatory Factors in Conscious Rats.
Increased activity of the renin-angiotensin system has been observed in congestive heart failure, left ventricular hypertrophy and post-myocardial infarction. However, the exact role of angiotensin II (Ang II) in development of these pathologic conditions is not well elucidated. Using an indwelling intramyocardial microdialysis catheter in conscious rats, we measured changes in cardiac interstitial Ang II, thromboxane B2 (TXB2) endothelin-1 (ET-1) and prostaglandin E2 (PGE2) in control animals (n=10) and 24h after complete occlusion of left anterior descending artery (LAD, n=10) in conscious rats. Cardiac interstitial Ang II was 307±27 pg/ml vs. 842±40 pg/ml (P<0.01), TXB2 154±6 vs. 193±31 pg/ml (P<0.01), ET-1 24±1 vs. 58±1 pg/ml (P<0.01) and PGE2 397±52 vs. 707±50 pg/ml (P<0.01) in control vs. LAD occlusion, respectively. We conclude that early after infarction, cardiac interstitial Ang II, TXB2, ET and PGE2 increase and may serve to promote local inflammation, vasoconstriction, thrombosis and remodeling.