Different adhesion types and active sensitivity of platelet subpopulations.

Two different adhesion patterns of blood platelets with different sensitivity to adenosine were demonstrated by means of reflection contrast microscopy with consecutive image analysis and cell affinity chromatography. High-performance liquid chromatography revealed that thrombin-induced serotonin release of adenosine-sensitive platelets was lower than that of adenosine-resistant cells. Our results indicate platelet heterogeneity and suggest that the platelets with lower adenosine sensitivity may be actively involved in the early interaction between platelets and injured endothelium.

[A rapid method of isolation of platelet membranes for radioligand and enzymatic assays]. / Bystryi metod polucheniia kletochnykh membran trombotsitov dlia radioligandnykh i énzimaticheskikh issledovanii.

A simple and rapid procedure for isolation of the total platelet membrane fraction by chromatography on Sepharose CL 6B has been developed. This method allows a rapid (25-30 min) one-step separation of the membrane fraction on 26 x 150 mm columns with a 20-21 mg recovery. The high degree of purity of membrane preparations was confirmed by a radioligand assay using [3H]adenosine and L-[3H]glutamic acid. The purity of membrane preparations is comparable with that of membrane fractions obtained by standard ultracentrifugation methods. The homogeneity of the membrane fraction was demonstrated by using marker enzymes of plasma, microsomal and mitochondrial membranes. This finding is very important in that it allows the isolation of fractions differing in their protein content with no effect on the method reproducibility. The high utility of the membrane preparations in receptor studies was demonstrated for high affinity binding sites for [3H]adenosine and L-[3H]glutamic acid.

[Changes in the activity of lactate dehydrogenase isoformes in mouse rhabdomyosarcoma under different proliferation conditions]. / Izmenenie aktivnosti izoform laktatdegidrogenazy v rabdomiosarkome myshi pri raznykh usloviiakh proliferatsii.

The activity of lactate dehydrogenase (LDH) isoenzymes was studied in clones of rhabdomyosarcoma (RMS) MX-53, being transplanted on mice of CC57W line. Clones obtained in lungs after the intravenous injection of a tumor cell suspension were transplanted into subcutaneous connective tissue (SCT) and eye anterior chamber (EAC). A study of LDH isoenzymes spectrum in transplants and native muscle tissues has been made using polyacrylamide gel electrophoresis and densitometry. We revealed a variability of LDH isoenzyme activity within one clone, and in population of clones under different proliferation conditions. Under all the proliferation conditions, we observed spectra characteristic of tumors of a given histogenesis with predominating activity of M-subunits. But during proliferation in EAC the M:H ratio decreased, and LDH spectra of tumor cells became more similar to the LDH spectrum of normal skeletal muscles. It is concluded that intra- and interclonal variations of the character "LDH isozyme spectrum" is strongly influenced by the environmental factors.