Improvement in fatty acid utilization in relation to a change in left ventricular hypertrophy in spontaneously hypertensive rats

Although fatty acid metabolism is reportedly impaired in myocardial hypertrophy, it is unclear whether the antihypertensive drugs are associated with improved fatty acid metabolism. In order to evaluate the effects of antihypertensive drugs on fatty acid metabolism and myocardial perfusion, the simultaneous uptake of iodine-125(125I)-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and thallium-201 (Tl) were measured in 3 groups of rats: (1) spontaneously hypertensive rats (SHR) without treatment (SHR-N), (2) SHR chronically treated with captopril (SHR-C), and (3) SHR chronically treated with hydralazine (SHR-H). Captopril and hydralazine were administered to their respective groups for 3 weeks from 12 weeks of age. The hearts were removed 10 min after simultaneous intravenous injections of BMIPP and Tl and the 125I and 201Tl counts were measured to calculate the uptake ratio. The systolic blood pressure (SBP) in SHR-N was 222+/-10 mm Hg, whereas the SHR-C and SHR-H groups showed significant SBP reduction (156+/-11, and 158+/-10 mm Hg, respectively) (p<0.01 each). The heart/bodyweight ratio was significantly lower in SHR-C (2.48+/-0.09) than in SHR-N (2.74+/-0.11) (p<0.05). However, there was no significant difference in the heart/bodyweight ratio between SHR-N and SHR-H (2.65+/-0.09). The ratio of BMIPP uptake to Tl uptake (BMIPP/Tl) was significantly higher in SHR-C (0.71+/-0.13) than in SHR-N (0.50+/-0.09) (p<0.05). However, BMIPP/Tl in SHR-H (0.53+/-0.09) was similar to that in SHR-N. These results suggest that captopril improves fatty acid metabolism in the hypertrophied ventricle in SHR. The metabolic alterations may improve with left ventricular hypertrophy regression but are not effected by the reduction of blood pressure only.