Increased Consumption of Vitamin A in the Heart under Oxidative Stress

Summary

Epidemiological and clinical studies examining the relationship between vitamin A and cardiovascular disease have traditionally used plasma concentrations as the sole indicator of vitamin A status with conflicting results. Using radiolabelled vitamin A, we show that under increased oxidative stress conditions in the heart failure subsequent to myocardial infarction, the heart increased its utilization of vitamin A. Steady state concentrations of vitamin A in these hearts or in the plasma were not affected. In the absence of a continuous supply of retinol through the plasma, vitamin A levels decreased significandy in an ex vivo oxidatively stressed isolated perfused heart. In vivo vitamin A levels in the heart failure may have been maintained by an increase in the mobilization of retinol from the liver through an increase in the activity of the bile salt dependent-retinol ester hydrolase enzyme. It is suggested that monitoring of the plasma concentrations of vitamin A may not be the best approach for assessing the utilization of vitamin A.