ABSTRACT
The possible mechanism of diabetic serum factor (DSF)-mediated lysosomal degranulation has been investigated. It was observed that pertussis toxin, sodium fluoride and vanadate could significantly inhibit DSF-mediated beta-glucuronidase release, whereas atropine exhibited only a partial blockage against DSF. Since DSF can generate toxic free radicals, various free radical quenchers were tested in order to evaluate their contributions. Superoxide dismutase was found to be the most effective in inhibiting lysosomal release as compared to catalase and peroxidase. The mixtures of all the enzymes failed to exhibit any additive effect. Interaction of DSF with heparin, insulin and Con A revealed that heparin can completely block DSF-mediated lysosomal release. The implications of the observations are discussed.
Subject(s)
Adult , Biological Factors/blood , Diabetes Mellitus, Type 2/blood , Female , Glucuronidase/blood , Humans , Male , Middle Aged , Neutrophils/enzymology , Protein Binding , Reference ValuesABSTRACT
Translocation of calcium activated neutral proteinase from cytosol to plasma membrane, concurrently with decrease in the activity of membrane bound Ca2+/Mg2+ ATPase has been detected in diabetic polymorphonuclear leucocytes. Plausible involvement of the extralysosomal proteinase in the derangement of the Ca2+/Mg2+ ATPase is indicated by non restoration of the enzyme activity on treatment with activators such as trypsin or calmodulin and enhanced membrane translocation of the proteinase observed with concomitant decrease in the activity of Ca2+/Mg2+ ATPase in normal neutrophils on insult with diabetic serum factor.
Subject(s)
Adult , Ca(2+) Mg(2+)-ATPase/blood , Calpain/blood , Diabetes Mellitus, Type 2/enzymology , Female , Humans , Male , Middle Aged , Neutrophils/enzymologyABSTRACT
With a view to determining the role of diabetic serum factor (DSF) in the progression of membrane pathology, time-dependent preincubation effects of DSF on certain membrane-bound enzymes of normal polymorphonuclear leucocytes (PMNL) have been studied. DSF is found to cause significant decrements in the activities of Na+/K+ ATPase, PLC and AcE of PMNL on in vitro incubation for 60 min, while the effect on Ca2+/Mg2+ ATPase appears only on prolonged incubation with an initial hike in activity at 5 min. The implications of these results have been discussed.