Abstract P155: Chronic Muscadine Grape Extract Intake Improves Diastolic Function Associated With Lower Circulating Aldosterone in Hannover Sprague Dawley Male Rats

Muscadine grapes are rich sources of polyphenols, which are natural anti-oxidants linked to cardiovascular health. Circulating aldosterone may contribute to cardiac diastolic dysfunction via pro-oxidant and pro-fibrotic effects. We investigated the effect of chronic treatment with a muscadine grape extract (MGE) on circulating aldosterone and cardiac function in Hannover Sprague Dawley (SD) rats, since we previously showed that male rats develop diastolic dysfunction by 60 weeks of age. MGE (Piedmont Research & Development Corp.) was administered in the drinking water (0.2 mg polyphenolics /mL) starting at 15 weeks of age. Control animals were given regular water. Animals were assessed after 15 and 30 weeks of treatment. At 30 weeks of age, male SD rats have higher systolic blood pressure (SBP, measured by tail-cuff plethysmography: 139 ± 5 vs. 124 ± 2, n = 7-8, p < 0.05), higher E/e’ (measured by Vevo LAZR ultrasound: 12.9 ± 0.7 vs. 10.9 ± 0.2, n = 5-8, p < 0.05), and lower ejection fraction (77 ± 2 vs. 82 ± 1, n = 5-8, p < 0.05) than females at 30 weeks of age. SBP was lower in MGE treated males (126 ± 2 vs. 139 ± 5, n=7-8, p < 0.05) but not in females at 30 weeks of age. At 45 weeks of age, MGE treated male rats had improved (lower) E/e’ ratio than control male rats (E/e’: 10.7 ± 0.6 vs. 13.4 ± 0.4, n = 7, p < 0.05). This effect was accompanied by lower serum aldosterone (15 ± 3 vs. 28 ± 3 ng/dL, n = 7, p < 0.05) at 45 weeks of age. The MGE effects were independent of differences in SBP, ejection fraction, cardiac output or LV mass at this time point in male rats. For the female SD rats, there were no differences in SBP, cardiac systolic or diastolic function comparing values at 30 and 45 weeks of age, and no effect of MGE treatment at either time point. Serum aldosterone was not lower in the female rats at 45 weeks of age relative to control females. Our data demonstrate sex differences in cardiac function in response to chronic MGE consumption in aging rats. The MGE-induced improvement in diastolic cardiac function in males is consistent with lower circulating aldosterone. Our results suggest a protective role for MGE in age-related cardiac dysfunction in males.