In vitro effects of polyvinylpyrrolidone and sucrose on the acetylcholinesterase,succinate dehydrogenase and lactate dehydrogenase activities in the brain

Summary The supernatant prepared from the brain tissue homogenate incubated in vitro in the presence of PVP or sucrose exhibits a decrease of AChE, SDH as well as of LDH activity. A 0.75% PVP solution inhibits AChE activity by 30%, LDH activity is inhibited by 35% and SDH activity by 40%. A two hours lasting effect of a 7.5% PVP solution at 3° C on enzymatic preparations induces in AChE 20% inhibition of its activity, in LDH an inhibition of 44% and in SDH the inhibition of its activity amounts to 74%. 1 M Sucrose inhibits AChE activity by 34%, LDH activity by 41% and SDH activity is inhibited by 31%. After two hours lasting effect of 1.4 M sucrose at 3° C on the supernatant the AChE activity is inhibited by 22% and that of LDH by 30%. The SDH activity was after a two hours lasting effect of 1 M sucrose at 3° C inhibited by 34%. The inhibition of activity of the above mentioned enzymes localized in brain cortex preparations was compared with the inhibition of activity of the isolated serum cholinesterase. 0.25 M Sucrose inhibited the activity of this enzyme by 25% and 0.75% PVP by 45%. A two hours lasting effect of 7.5% PVP or 1 M sucrose at 3° C on the cholinesterase induced a 40% and 22% inhibition respectively. After double washing of the brain cortical minced tissue, prepared in a 7.5% PVP containing solution, AChE activity was constant. By triple washing of the brain cortical crude mitochondrial fraction, exposed for two hours at 3° C to the effect of 1 M sucrose, SDH activity was also constant.Abbreviations AChE acetylcholinesterase (EC 3.1.1.7.) - INT 2(p-iodophenyl)3-p-nitrophenyl-5-phenyl tetrazolium chloride - LDH lactate dehydrogenase (EC 1.1.1.27.) - PMS phenazine methosulfate - PVP polyvinylpyrrolidone - SDH succinate dehydrogenase (EC 1.3.99.1.)