Mersalyl, a sulfhydryl reagent, alters the solubility of myosin and cytoskeletal proteins of human platelets.

We have examined the effect of a mercurial sulfhydryl reagent, mersalyl, on the protein composition of cytoskeletons by SDS-polyacrylamide gel electrophoresis after treatment of human platelets with Triton X-100 (Triton) containing mersalyl and Ca2+, and have found that mersalyl alters the protein composition of cytoskeletons in a Ca2+-dependent manner. At 1 X 10(-7) M Ca2+, 0.2 mM mersalyl, which represents approximately the equivalent amount of sulfhydryl of platelet suspensions that we used, specifically made myosin insoluble. The amount of myosin in Triton-mersalyl residues was increased by increasing the Ca2+ concentration of Triton lysis buffer. Actin-binding protein, 235 kDa polypeptide and alpha-actinin-like protein were decreased in Triton residues by mersalyl at Ca2+ concentrations less than 1 X 10(-7) M, while these polypeptides in Triton residues were increased by mersalyl in the presence of more than 2 X 10(-7) M Ca2+. Electron microscopic study revealed the presence of thick filaments with an appearance similar to that of the thick filaments of platelet myosin. Thus, the modification with mersalyl of sulfhydryls of platelet polypeptides along with changes in Ca2+ concentrations within a physiological range leads to changes in solubility of, and filament formation of, myosin, actin and other cytoskeletal proteins.

[The ATPase content of the blood neutrophils and lymphocytes in patients with chronic periodontitis]. / Soderzhanie ATFaz v neitrofilakh i limfotsitakh krovi u bol'nykh s khronicheskim parodontitom.

Chronic periodontitis is associated with reduced immunologic reactivity of the body, that may present as disturbed status of the lymphocytes and neutrophils due to reduced activity of adenosine triphosphatases. Drug therapy of periodontitis, physiotherapy, oral hygiene, sodium chloride reducing diets are conductive to improvement of the clinical status of the periodontium and to recovery of ATPase activities.

[Studies on aging enzyme activities of the human dental pulp blood vessels].

Histochemical distribution and age changes of alkaline phosphatase (AKPase E. C. 3. 1. 3. 1) and adenosine triphosphatase (ATPase E. C. 3. 6. 1. 3) in normal human dental pulp blood were investigated qualitatively and quantitatively. 42 dental pulp samples from patients aged 10 to 70 years old were divided into three groups. Results showed that accompanying aging, activities of AKPase and ATPase of dental pulp blood vessels decreased. AKPase staining quantities for group one (10-30 years), group two (31-50 years) and group three (51-70 years) were 40.62 +/- 13.79, 36.75 +/- 9.78 and 19.20 +/- 5.35 and ATPase staining quantities were 33.00 +/- 10.09, 27.53 +/- 16.60 and 23.27 +/- 5.04 respectively. The endothelial cells of capillaries in dental pulp changed greatly. With aging, metabolic ability of dental pulp decreased gradually. In addition, it was observed that the capillaries in sub-odontoblasts decreased and odontoblast layer became thin with aging. The close association of the capillaries of the pulp to the odontoblasts had been demonstrated.

[Isolation and properties of anion-sensitive adenosine triphosphatase from erythrocyte membranes]. / Vydelenie i svoistva anionchuvstvitel'noi adenozintrifosfatazy iz membran éritrotsitov.

Using the non-ionic detergent Triton X-100 and gel-chromatography, an anion-sensitive ATPase was isolated from rat and rabbit erythrocyte membranes. The ATPase preparations possess no Na, K- or Mg, Ca-ATPase activities. ATPase from rat erythrocyte membranes is made up of five subunits with molecular weights of 58 000 (alpha), 50 000 (beta), 36 000 (gamma), 25 000 (delta) and 12 000 (epsilon) and can be represented by the formula alpha 3 beta 3 gamma delta epsilon.

Erythrocyte membrane ATPases in diabetes: effect of dikanut (Irvingia gabonensis).

The levels of the three ATPases found in the erythrocyte membrane of diabetic patients were significantly lower than normal subjects. The distribution of the enzymes was also different. Na+,K+-ATPase and Mg2+-ATPase reflected the status of blood glucose more than Ca2+-ATPase. The ratio between two of the ATPases was sensitive to glycemic response. When dikanut, a viscous preparation, was fed to diabetics for 4 weeks, blood glucose became normal and the activities of the three ATPases increased significantly. The ratio among the enzymes also approached that of normal subjects. A relationship was found between the blood glucose level and erythrocyte membrane ATPases which, if linked to insulin binding or level, may provide a rapid inexpensive assay in diabetes research.

Comparative extraction of erythrocyte EDTA-membrane proteins by some ionic and non-ionic detergents.

In order to examine whether it would be possible to obtain, by a simple extraction procedure from EDTA-erythrocyte-membranes, a partially purified preparation of the "band 3 zone" proteins, we have tested four solubilizing agents of common use. Detergents, both ionic (DOC and SDS) and non ionic (Tween 80 and Triton X-100), were not able, in our experimental conditions, to completely solubilize erythrocyte fragmented membranes which had previously been washed in EDTA-buffers. However, they were able to solubilize some of the membrane proteins, which could then be separated by SDS-PGE. The PGE densitometric profiles reported in this communication indicate that the protein mixture extracted by the ionic detergents DOC and SDS qualitatively reflects the protein composition of the membranes. Among the non ionic detergents, on the other hand, Triton X-100 appeared to be able to extract mainly one band (most probably the band 3 zone), while Tween 80 did not apparently extract any of the membrane proteins. Detergent concentrations, medium composition and experimental procedures are described in detail.

Calcium and magnesium ATPases of the spectrin fraction of human erythrocytes.

Using a rapid method of preparation, spectrin has been isolated from human erythrocytes and its ATPase activity investigated. The ATPase activity with calcium has two distinct components, one with optimal activity when calcium and ATP are of equal concentration (low-Ca-ATPase) and another which is activated above 1 mM CaCl2 and is maximal at 100 mM CaCl2. There is also a Mg-ATPase with maximal activity at 10 mM MgCl2. The high-Ca-ATPase of spectrin, but not the low-Ca-ATPase, is inhibited by magnesium, while the Mg-ATPase is inhibited by Ca in excess of ATP. None of these activities exhibits the calcium-stimulated magnesium-dependent activity characteristic of the red cell calcium pump.

A sodium-specific membrane permeability defect induced by phospholipid vesicle treatment of erythrocytes.

Treatment of human erythrocytes with phospholipid vesicles induces a selective membrane permeability defect which leads to osmotic lysis. The defective cells exhibit a massive sodium ion leak while maintaining normal impermeability to other cations, anions, and neutral small molecules. The sodium ion influx and resulting hemolysis may be inhibited by increased pH, by tetrodotoxin, and by reintroduction of vesicle-extracted proteins into the cell. These characteristics suggest that phospholipid vesicle treatment destroys the cell by disrupting a membrane protein system involved in regulation of cation permeability.

[Interaction of vasoactive substances with phospholipid and erythrocyte membranes]. / Vzaimodeistvie nekotorykh vazoaktivnykh veshchestv s fosfolipidnymi i éritrotsinymi membranami.

Experiments with phospholipid liposomes, red cells (or their shades) of man and pigeon, modulated with helium-neon laser, were made to study the effects of papaverine, verapamil, phosphadene, theophylline, nicotinic acid, acetylcholine, adenosine and hydralazine on the intensity of the own fluorescence of the membrane and of the membrane-bound probe, 1,8-AHC, segregation of methylene blue by the red cell mass, red cell resistance to osmotic or UV-induced hemolysis as well as on the activity of Na-, K-, Mg- and Ca-dependent ATPases of the red cell shades of the donor or pigeon. As regards the tests used, the most differentiated membranous effects were discovered for the drugs under study within the concentration range 10(-5)-10(-8) M. The vasoactive agents administered at equimolar end concentrations produced quantitatively and qualitatively inconsistent effects on the parameters tested. They increased (with the exception of acetylcholine) segregation of the cationic dye, reduced the fluorescence intensity of the probe, and elevated the resistance to osmotic and UV-induced hemolysis. The latter circumstance is likely to be determined by activation of membranous ATPases. Exposure to laser potentiated the membrane-stabilizing action of the substances under consideration.