IN VITRO EFFECT OF L-CARNITINE ON THE ACTIVITY OF LYSOSOMAL CYSTEINE PROTEASES AND THE STATE OF LYSOSOMAL MEMBRANE

Abstract

The influence of L-carnitine in vitro on the lysosomal cysteine proteinase activity and stability of the lysosomal membrane of the liver homogenates of intact sexually Mature female rats of Wistar line weighing 280-330 g were studied. In the experimental groups isolated lysosomes were incubated in vitro in a solution of L-carnitine during 1, 2 and 4 hours, in the control groups in vitro incubation was carried out in a medium of isolating solution. The activity of ca-thepsins B, L and H was investigated by spectrofluorimetric method of Barrett & Kirschke in two fractions - lysosomal and outside of lysosomes. The activity of acid phosphatase was used as the main marker of a membrane labilization. In vitro incubation of lysosomes showed that carnitine at a concentration of 5 mM increases the total activity of cathepsin B in a one-hour incubation at 73,2% (p=0,008), cathepsin L in a two- and four-hour incubation - at 77,7% (p=0,005) and 42,3% (p=0,013) respectively, and reduces the overall activity of the cathepsin H in a one-hour incubation at 200,0% (p=0,008), in a two-hour - by 67,9% (p=0,05), in a four-hour -27,1% (p=0,02). In addition, incubation in 5 mM L-carnitine solution leads to an increase of unsedimentable activity and fall sedimentaries activity for cathepsin L in a two-hour, and for acid phosphatase - in a two - and four-hour exposure. 5 mM L-carnitine in one - and two-hour incubation stabilizes lysosomal membrane (whereas increase in incubation time up to 4 hours leads to its damage) and increases the selective permeability of the lysosomal membrane for the studied cathepsins, to the greatest extent - for cathepsin H.