David M. Kurtz

Effect of Temperature and Storage Time on Sorbitol Dehydrogenase Activity in Sprague-Dawley Rat Serum and Plasma

Sorbitol dehydrogenase (SDH) is a liver-specific enzyme sensitive to the detection of acute hepatocellular injury in rats; however, its usefulness has been questioned as being a highly labile enzyme. The purpose of this study was to determine the stability of serum and plasma SDH activity from both untreated rats and those treated with a single low dose injection of D-(þ)-galactosamine hydrochloride, a known hepatotoxicant. After collection and initial SDH activity analysis, aliquots of serum and plasma were stored at 21 C, 4 C, and 80 C and analyzed at various time points. Serum SDH activity was stable for 4 hr at 21 C. At 4 C, serum SDH activity was stable for 24 hr, after which it significantly increased; it was not stable at 80 C. Plasma SDH activity was significantly increased by 4 hr at 21 C and 4 C, and by 48 hr at 80 C. Analysis of plasma SDH activity should occur shortly after blood collection. Analysis of serum SDH activity should occur within 4 hr of collection or stored at 4 C and measured within 24 hr. Extended storage at 4 C or 80 C for the measurement of serum or plasma SDH activity cannot be recommended due to the observed substantial elevations in SDH activity.