Substrate Specificity of Na+,Cl-(HCO3-)-ATPase.

We studied substrate specificity of Na+,Cl-(HCO3-)-ATPase. In most cases, replacement of ATP for other phosphate-containing substances resulted in not only pronounced suppression of phosphohydrolase reactions, but also dramatic changes of their responsiveness to the stimulating effect of monovalent ions. The data showed that Na+,Cl-(HCO3-)-ATPase is a highly specific enzyme for ATP.

Effect of Ionophores on Activity of Na+,Cl-(HCO 3- )-ATPase.

We studied the effects of ionophores on activity of Na+,Cl-(HCO 3- )-ATPase. The most significant effect on the activity of this enzyme was produced by protonophore 2,4-dinitrophenol. The effect of this drug largely depended on the cation and anion composition and pH of the incubation medium and its pH. Activity of Na+,Cl-(HCO 3- )-ATPase increased at neutral and weakly alkaline pH and decreased at pH below 6.5-6.7. In control animals (without histamine injection) with very weak or absent Na+,Cl-(HCO 3- )-ATPase activity, the observed effect of the protonophore on ATPase activity was also virtually absent. The stimulatory effect of other ionophores (monensine, valinomycin, and A23187) was significantly weaker and depended on pH of the incubation medium, its cationic and anionic composition, and concentration of these ionophores.

Ca²âº ions regulate activity of Na⁺ ,Cl⁻(HCO3 ⁻)-ATPase in the mucosa of rabbit small intestine.

We studied the effects of bivalent metal ions on activity of Na(+),Cl(-)(HCO3 (-))-ATPase was studied. In contrast to Ba(2+), Co(2+), Zn(2+), and Mn(2+) ions, Ca(2+) and Mg(2+) ions in a concentration of 0.25 mM completely inhibited this enzyme. Histamine in vivo significantly decreased the inhibiting effect of Ca(2+) on Na(+),Cl(-)(HCO3 (-))-ATPase. A possible mechanism of regulation of enzyme activity by Ca(2+) ions and its possible relation with CFTR protein providing permeability of enterocyte apical membrane for Cl(-) ions was proposed.

Effect of cholera toxin on ATPase activities in rabbit small intestinal mucosa.

Cholera toxin induced the appearance of ATPase activity in rabbit small intestinal mucosa. This enzyme significantly differed from other ATPases, including Na(+),K(+)-ATPase and HCO3(-)-ATPase in the small intestinal epithelium of rabbits, by some properties, in particular, by relation to divalent and monovalent cations and anions, pH optimum, substrate specificity, and inhibitory analysis.

[Properties of Na+/HCO3-(Cl-)-stimulated ATPase in rabbit small intestinal mucosa]. / Svoistva Na+/HCO3-(Cl-)-stimuliruemoi ATPazy slizistoi obolochki tonkogo kishechnika krolikov.

It has been demonstrated that histamine induces in rabbit small intestine an ATPase activity which is stimulated by NaCl or NaHCO3. The Na+/HCO3- (C1-)-stimulated ATPase activity, unlike the Mg2+,HCO3(-)-ATPase activity, has a pH optimum at pH 6.2, is inhibited by ethacrynic acid (10(-4) M) and bivalent metal ions (but not 10(-2) M thiocyanate). The substrate specificity of Na+/HCO3- (C1-)-ATPase and its regulation by Ca2+ ions has been studied. The feasible role of the enzyme in secretion is discussed.

[A method for correcting dislocation in hemorrhages into the cerebral hemispheres]. / Sposob korrektsii dislokatsii pri krovoizliianiiakh v polushariia bol'shogo mozga.

Hypertension consequent upon increasing brain edema, and intercerebral pressure gradient which is the cause of transverse dislocation diminish with the use of a method which provides for hydrodynamic equilibrium. The method consists in connecting the ventricle of the intact cerebral hemisphere to a balloon located in the cavity of the removed hematoma according to the principle of communicating vessels. The craniospinal pressure gradient is removed by additional catheterization of the spinal subarachnoid space and its connection to the ventricle and balloon according to the same principle.

[Characteristics of collateral circulation in the ophthalmic artery before and after cerebral revascularization in patients with multiple occlusive diseases of the major arteries of the head]. / Osobennosti kollateral'nogo krovoobrashcheniia po glaznoi arterii do i posle revaskuliarizatsii mozga u bol'nykh s mnozhestvennymi okkliuziruiushchimi porazheniiami magistral'nykh arterii golovy.

The status of the collateral blood flow was examined before and after establishment of ++extra-intracranial microarterial anastomosis (EICMA) in 70 patients with occlusion of the internal carotid artery. Of these, 93% of the patients also had lesions of the other main arteries of the head. It has been established that in concomitant lesions of the main arteries of the brain, the role of the ophthalmic artery (OA) rises as to the compensation for the blood flow in the damaged hemisphere. Involvement of the ophthalmic anastomosis into blood supply of the damaged hemisphere was found to inversely correlated to EICMA function. Active functioning of EICMA brings about a decrease of the retrograde blood flow in the OA and in some cases, alteration in the direction of the blood flow in that artery, namely from retrograde to antegrade. Nevertheless additional blood flow via EICMA promotes elevation of the level of the cerebral blood flow in the regions of the middle cerebral artery basin, supplied via the microarterial anastomosis.

[Combined surgical treatment of associated lesions of the major arteries of the head]. / Kombinirovannoe khirurgicheskoe lechenie sochetannykh porazhenii magistral'nykh arterii golovy.

Concurrent affection of the main arteries of the head is the cause of vascular cerebral insufficiency in more than half of the patients, which makes necessary combined operations on the extra- and intracranial arteries. The sequence of the operations is determined by the degree of the threat of occlusion of the stenosed artery or by the side on which the cerebrovascular insufficiency is manifested. Information on the regional cerebral blood flow and the results of ultrasonic dopplerography and computed tomography are additional criteria for determining the sequence and the terms of the operations. Experience in 61 combined operations allows the authors to consider them to be an effective method for the surgical management of concurrent affections of the main arteries of the head.

[Effect of divalent cations on the properties of NaCl-stimulated ATPase activity in the mucosa of the rabbit small intestine]. / Vliianie dvukhvalentnykh kationov na svoistva NaCl-stimuliruemoi ATF-aznoi aktivnosti v slizistoi obolochke tonkoi kishki krolikov.

The effect of bivalent cations on NaCl-stimulated ATPase activity in rabbit small intestinal mucosa was studied. Unlike Ba2+ and Zn2+, Ca2+ and Mg2+ added to the incubation medium at a concentration of 0.25 mM completely change ATPase activity. Histamine considerably reduces the inhibitory effect of Ca2+ and Mg2+ on NaCl-stimulated and oligomycin-inhibited ATPase activity. Possible mechanisms of the enzyme activity control in the cell are discussed.

[Regulation of cerebral circulation in an upright posture of the human trunk]. / K voprosu o reguliatsii mozgovogo krovoobrashcheniia pri vertikal'nom polozhenii tulovitsa cheloveka.

The functional mechanisms responsible for orthostatic tolerance of cerebral circulation in the normal man and in ambulatory and bedridden neurosurgical patients were investigated, using the following methods: cerebral blood flow by means of xenon-133 clearance, measurement of brain perfusion pressure, ventricular pressure, acid-base equilibrium in the blood flowing in and out of the brain, determination of cardiac output and stroke volume, electroencephalography, and rheography of cerebral and peripheral vessels. In the normal men and patients with compensated neurosurgical pathologies, the transfer into the head-up position induced small changes in the systemic and cerebral regional circulation. This was associated with complex reactions of the vascular system triggered by the receptors of the sinocarotid area. The normal response of the vascular system to the orthostatic load involved dilatation of cerebral and constriction of peripheral arteries, tachycardia, increased central venous pressure, moderate decrease of brain perfusion pressure and intraventricular pressure. In vascular pathological reactions constriction of peripheral arteries and veins was disturbed; cardiac output and stroke volume, cerebral blood flow velocity, central venous and intraventricular pressures were decreased.

[Effect of monovalent and bivalent cations and anions on the properties of ATPase from rabbit small intestine mucosa]. / Vliianie odnovalentnykh i dvukhvalentnykh kationov i anionov na svoistva ATPaz v slizistoi obolochke tonkogo kishechnika krolikov.

The effects of monovalent cations and anions on the ATPase activity of rabbit small intestine mucosa membranes was studied. It was shown that the small intestine mucosa contains the ATPase activity sensitive to NaCl and NaHCO3. This activity, in contrast to the HCO3--ATPase activity, is inhibited by ethacrinic acid, is practically insensitive to thyocyanate, has a pH optimum of 6.2, is unstable upon storage and is not inhibited by 2 mM EDTA. The catalytic and regulatory properties of HCO3--ATPase and NaCl/NaHCO3-stimulated ATPase were compared; their possible involvement in secretion in small intestine epithelium is discussed.

[Effect of body position on cerebral circulation in neurosurgical patients]. / Vliianie polozheniia tela na mozgovoe krovoobrashchenie u neirokhirurgicheskikh bol'nykh.

The mechanisms of the regulation of blood drainage from the brain were defined more precisely in 87 neurosurgical patients on the basis of comprehensive examination of cerebral circulation. The vertebral venous plexus was found to play the most important role in this process. Under normal conditions, when the patient is lying blood drains along the internal jugular veins, when he is sitting it drains mainly along the vertebral venous plexus. In patients remaining in a horizontal position for a long period of time the regulation of venous drainage is impaired. In such cases blood drains along the internal jugular veins and the vertebral venous plexus both when the person is lying and when he is sitting. This may cause a deterioration in the condition of bed-ridden patients during and after an operation performed with the patient in a sitting position.