Cardiac catechol O-methyltransferase and monoamine oxidase activity in congestive heart failure

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Abstract
The role of those enzymes which inactivate norepinephrine (NE), catechol O-methyl transferase (COMT), and monoamine oxidase (MAO) was evaluated in experimental cardiac hypertrophy and congestive heart failure (CHF). COMT and MAO activity, and NE content were determined in portions of the right and left ventricle of normal cats and those with constriction of the pulmonary artery. In the CHF group there was a significant increase in right ventricular weight and a reduction in NE and MAO activity/unit weight, while COMT concentration was unchanged. Total ventricular MAO activity in the CHF group was significantly reduced in the left ventricle and increased in the right, but less than the weight increase. Total COMT activity paralleled the weight change. Since a portion of MAO is located within sympathetic neurons, the results are compatible with a functional cardiac denervation occurring in association with cardiac hypertrophy and congestive failure.