Abstract 363: Recovery of Exercise Intolerance and Ventricular Dysfunction of Infarcted Spontaneously Hypertensive Rats After Oral Treatment With an Agonist of Adenosine Receptor

Abstract

Severe ventricular dysfunction is observed in spontaneously hypertensive rats (SHR) submitted to myocardial infarction (MI). The present work evaluates the cardioprotective effects of oral administration of a novel agonist of adenosine A2A receptor, LASSBio-294, in infarcted SHR. Methods: Male SHR (12-14 wks old) were randomly divided into groups: sham and infarcted (MI) which were either treated orally with vehicle or LASSBio-294 (10 mg/kg) for 28 days. Before and after the animals were treated with LASSBio-294, cardiac function and exercise capacity were evaluated through the echocardiography and treadmill test. Mean blood pressure (MBP), left ventricular end diastolic pressure (LVEDP) and negative dP/dt were also determined. Fibrosis in heart sections were detected using H&E staining. Immunohistochemical staining for TNF-alpha and SERCA2a in LV tissues were observed. Results: MI in SHR reduced the running distance from 257.9 ± 13.2 to 39.0 ± 4.4 m which normalized to 296.0 ± 26.4 m after treatment with LASSBio-294. Reduced anterior wall thickness was observed after MI (0.51 ± 0.14 mm) which was prevented with treatment (1.65 ± 0.21 mm). Ratio of early and late transmitral filling velocity was reduced from 1.48 ± 0.09 to 0.99 ± 0.04 and recovered to 1.35 ± 0.07 after treatment. MBP was reduced from 169.0 ± 5.6 to 120.4 ± 7.4 mmHg in SHR-IM treated with LASSBio-294. Increased LVEDP of 25.6 ± 3.2 observed in SHR-IM was reduced to 7.3 ± 1.0 mmHg after treatment. The -dP/dt was reduced in SHR-MI to -5698 ± 408.1 mmHg/s and returned to -7894 ± 631.6 mmHg/s after LASSBio-294 treatment. There was an increase in collagen deposition after MI (from 14.5 ± 3.5 to 59.8 ± 5.4 %) which was prevented with LASSBio-294 treatment (29.5 ± 2.2 %). Increase of positive staining for TNF-α was observed in SHR-MI (from 9.5 ± 1.0 to 32.3 ± 2.1%) which recovered in SHR-MI treated group (14.4 ± 1.3%). Also, the expression of SERCA2a was reduced in ventricular muscle from SHR-IM (from 68.7 ± 5.1 to 21.4 ± 2.3 %) which partially recovered to 40.6 ± 1.19% with LASSBio-294 treatment. Conclusion: LASSBio-294 reduced exercise intolerance, prevented cardiac remodeling and diastolic dysfunction in infarcted SHR.