AJP - Gastrointestinal and Liver Physiology, Vol 269, Issue 3 396-G399, Copyright © 1995 by American Physiological Society
Reduced glutathione release into rat plasma by extrahepatic tissues
R. F. Burk and K. E. Hill
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2279, USA.
The liver is the only tissue that has been demonstrated directly to secrete
glutathione into the plasma. The present experiments were carried out to
determine whether extrahepatic tissues secrete the reduced form of
glutathione (GSH) as well. Phorone, a compound that depletes glutathione
through glutathione S-transferase-dependent conjugation with GSH, was
administered to fasted rats in a dose of 250 mg/kg. Two hours later,
glutathione concentrations were reduced to the following: liver, 2%;
plasma, 17%; and skeletal muscle, 63%. This showed that plasma and muscle
glutathione were not depleted to the same extent as liver glutathione.
Glutathione concentration in plasma from the hepatic vein was not higher
than concentrations in plasma from the portal vein and from the aorta,
indicating that the depleted liver was not releasing glutathione into the
plasma. Total glutathione and GSH were higher in plasma from the femoral
vein than in plasma from the aorta under these same conditions. This
indicates that the leg releases GSH under conditions of absent hepatic GSH
release when plasma glutathione concentrations are decreased. These results
suggest that muscle secretes GSH into the extracellular space and raise the
possibility that other tissues secrete GSH as well. Further studies will be
required to determine whether GSH release by extrahepatic tissues is
affected by the plasma glutathione concentration.
