Role of hepatic adenosine triphosphate in BSP transport and metabolism in vivo

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Abstract
Current concepts suggest that excretion of BSP (sulfobromophthalein) from liver into bile and probably hepatic BSP uptake are energy-dependent processes. To assess the role of ATP, the prime source of energy in liver, for hepatic BSP transport in vivo, the nucleotide was depleted in liver by administration of ethionine or ethionine and 2, 4-dinitrophenol (DNP). Two hours after ethionine and 1 hr. after DNP injection, BSP in an amount exceeding its excretory Tm was infused into experimental and control animals. Hepatic ATP concentration declined to 55-7 and 24. 5 percent of control after ethionine and ethionine-DNP, respectively, whereas hepatic protein and total lipid concentration, BSP-conjugating enzyme activity, glutathione, and morphology remained essentially unaltered. BSP uptake was comparable in the ATP-depleted and control animals. In addition, the concentration of free and conjugated BSP in plasma, liver, and bile of experimental and control rats at 30 min. and their biliary excretion of the injected dye in 30 min. were similar, despite a 75 percent depletion of hepatic ATP in the experimental group. The implications of these findings are discussed.