EFFECTS OF ACUTE, SUBMAXIMAL EXERCISE ON VITAMIN-B-6 METABOLISM IN THE RAT

The effect of acute exercise on vitamin B-6 metabolism was assessed in Wistar rats (n=40) submitted to forced-swimming by measuring B-6 vitamers (Pyridoxal 5'-phosphate, PLP; pyridoxal, FL; pyridoxamine 5'-phosphate, PMP; pyridoxamine, PM; pyridoxine, PN) and pyridoxic acid (4-PA) by a reverse-phase liquid chromatography method in plasma, gastrocnemius muscle, liver, brain, heart, kidneys, and adrenals at rest (n=8) and after swimming for 1.0 h (n=8), 1.5 h (n=8), 2.0 h (n=8), and 2.5 h (n=8). Results showed a significant increase in plasma total vitamin B-6 (PLP + PL + PM + PN), PLP and 4-PA levels in the exercised animals vs. control animals. Mean PLP muscle levels (nmol/g) increased significantly after 1.5 and 2.5 h of swimming. Liver PLP, FL, PM and total vitamin B-6 also increased significantly in the exercised animals. Concentrations of B-6 compounds in heart, brain, kidneys, and adrenals were not affected. Vitamer tissue content was also expressed as total amount (nmol per organ) since liver and muscle weights changed significantly after exercise. PLP, PMP and total vitamin B-6 increased in muscle while PLP tended to decrease in liver. Our results indicated that acute exercise induced changes in vitamin B-6 metabolism including a retentive capacity and temporary deposition of vitamin B-6 stores in skeletal muscle. Further studies are needed to delineate the mechanisms involved in the regulation of vitamin B-6 distribution, transport, and storage during exercise.