Sensitivity of ketogenesis and citric acid cycle to stevioside inhibition of palmitate transport across the cell membrane

The effect of stevioside, an inhibitor of long-chain fatty acid transport, on ketogenesis and on [14C]CO2 production from [1-14C] palmitate (100-300µM) was investigated in the isolated and hemoglobin-free perfused rat liver. Stevioside (2.5mM), a sweet glycoside found in Stevia rebaudiana leaves, inhibited both parameters, but had a lower effection on [14C]CO2 production. At 300µM palmitate and 150 µM albumin, for example, ketogenesis was inhibited by 66.3%, whereas no significant inhibition of [14C]CO2 was demonstrable. These results were interpreted to reflect 1) different degress of saturation of the citric acid cycle and the ketogenic patheay and 2) changes in the redox state of the mitochondrial NAD+-NADH couple which may also occur upon stevioside infusion