Membrane effects of vitamin E deficiency: bioenergetic and surface charge density studies of skeletal muscle and liver mitochondria

Abstract

Vitamin E deficiency in rats increased the sensitivity of liver and muscle mitochondria to damage during incubation at various temperatures, irradiation with visible light, or steady-state respiration with substrates. In all cases, vitamin E-deficient mitochondria exhibited increased lipid peroxidation, reduced transmembrane potential, decreased respiratory coupling, and lower rates of electron transport compared to control mitochondria. Muscle mitochondria always showed greater negative inner membrane surface charge density, and were also more sensitive to damage than were liver mitochondria. Vitamin E-deficient mitochondria also showed slightly more negative inner membrane surface charge density compared to controls. The relationship observed between greater negative surface potential and increased sensitivity to damage provides for a new and sensitive method to probe further the role of surface charge in membrane structure and function. Implications of these new findings for the well-known human muscle myopathies and those experimentally induced by vitamin E deficiency in animals are discussed.