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PubMed1983

Characterization of detergent-solubilized adenosine triphosphatase of chromaffin granule membranes.

Purified bovine chromaffin granule membranes contain approximately 24 pmol/mg protein (16 copies per granule) of an F1-like adenosine 5'-triphosphatase, and 340 pmol/mg protein (200 copies per granule) of a low-molecular weight protein which reacts covalently with dicyclohexylcarbodiimide. These co-purify on electrofocusing and exclusion chromatography and are apparently components of a proton-translocating adenosine triphosphatase complex, that is involved in maintaining the high concentration of catecholamines in the granules. The membranes contain another adenosine 5'-triphosphatase, of lower molecular weight, which is sensitive to inhibition by vanadate but relatively insensitive to dicyclohexylcarbodiimide. The function of this enzyme is unknown.

Adenosine Triphosphatases↗
PubMed1997

Equilibrium of phosphointermediates of sodium and potassium ion transport adenosine triphosphatase: action of sodium ion and Hofmeister effect.

Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with P(i) in the presence of K+. We studied equilibrium between these states at 4 degrees C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P <--> E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165-182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP x dephosphoenzyme and ADP x E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319-5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP x E1P over ATP x dephosphoenzyme. Thus Na+ can dissociate from E1P x Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme.

Adenosine Diphosphate↗
PubMed1998

Evidence for an allelic association between bipolar disorder and a Na+, K+ adenosine triphosphatase alpha subunit gene (ATP1A3).

BACKGROUND: Disturbances in central nervous system Na+, K+ adenosine triphosphatase (ATPase) activity have previously been proposed as being involved in the pathophysiology of bipolar mood disorder. METHODS: We have examined one particular alpha subunit of this enzyme for allelic association in a sample of 85 Irish bipolar patients and 85 matched controls. RESULTS: There was evidence for an overall allelic association between the disease and a dinucleotide polymorphism within the ATP1A3 gene (p = .022). Subjects were then analyzed on the basis of a number of criteria, and the significance of the association increased when cases were divided based on the nature of the first episode. Patients who presented with a depressive episode first showed a significant association (p = .001) with this polymorphism. CONCLUSIONS: The results presented here provide preliminary evidence of an association between bipolar disorder and an alpha subunit of Na+, K+ ATPase, the expression of which predominates in the brain.

Adult↗
PubMed1995

The effect of thyroid hormone treatment on the gene expression and enzyme activity of rat liver sodium-potassium dependent adenosine triphosphatase.

The effects of thyroid hormone (T3) treatment on liver Na,K-adenosine triphosphatase (Na,K-ATPase) at the levels of subunit messenger RNA (mRNA), enzymatic activity, and enzyme content were studied in euthyroid rats injected for 5 consecutive days with T3. Northern and slot blot analyses of polyadenylated mRNA revealed that T3 treatment coordinately increases the level of mRNA encoding the alpha 1- and beta 1-subunits, approximately 4- and 3-fold, respectively, above basal levels. To determine whether this increase in the subunit mRNA consequently results in an increase in the synthesis of the enzyme, a modified liver cell fractionation procedure was developed, and the subcellular fractions from control and T3-treated livers were examined biochemically. Western blot analysis and Na,K-ATPase assay demonstrated that T3 treatment resulted in a 2-fold increase in both the amount and activity of the enzyme. Furthermore, the Western blot analysis of endoglycosidase-H-treated membrane fractions revealed an increase in the amount of the precursor beta-subunit in the T3-treated liver rough microsomal fraction, suggesting that an increase in subunit synthesis contributes at least partially to the increase in the rat liver Na,K-ATPase by T3 treatment.

Animals↗
PubMed1981

The influence of nicergoline on reaction kinetics of synaptosomal adenosine triphosphatases from porcine brain.

10-Methoxy-1,6-dimethylergoline-8beta-methanol-5-bromonicotinate (nicergoline) has in vitro a modulatory effect upon reaction kinetics of two synaptosomal adenosine triphosphatases from porcine brain: Na,K-dependent ATPase and Ca,Mg-dependent ATPase. Nicergoline is a non-competitive inhibitor of synaptosomal Ca,Mg-dependent ATPase in vitro; thus, if its in vivo concentration reaches a sufficiently high level, the rate of exchange of Ca and Mg ions between the intra- and the extracellular spaces of neurons slows down. In vivo effect of nicergoline upon reaction kinetics of synaptosomal Na,K-dependent ATPase is complex; below 80 micromol/l ATP it is an activator, and above 80 micromol/l ATP it is an inhibitor or enzyme. It decreases Km for ATP from 310 micromol/l in the absence, to 70 micromol/l in the presence of 0.3 mmol/l drug. It is believed that, in vivo, nicergoline helps to level or normalize the rate of physiological processes energetically coupled to synaptosomal Na,K-dependent ATPase, by moderately accelerating the slow and strongly inhibiting the fast reaction rates by ATP hydrolysis.

Adenosine Triphosphatases↗
PubMed1976

Mitochondrial adenosine triphosphatase of the fission yeast, Schizosaccharomyces pombe 972h-. Changes in activity and inhibitor-sensitivity in response to catabolite repression.

1. The specific activity of mitochondrial ATPase (adenosine triphosphatase) in extracts of Schizosaccharomyces pombe decreased 2.5-fold as the glucose concentration in the growth medium decreased from 50mM to 15mM. 2. During the late exponential phase of growth, ATPase activity doubled. 3. Sensitivity to oligomycin and Dio-9 as measured by values for I50(mug of inhibitor/mg of protein giving 50% inhibition) at pH 6.8 increased sixfold and ninefold respectively during the initial decrease in ATPase activity, and this degree of sensitivity was maintained for the remainder of the growth cycle. 4. Increased sensitivity to NN'-dicyclohexylcarbodi-imide, triethyltin and venturicidin was also observed during the early stage of glucose de-repression. 5. Smaller increases in sensitivity to efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diaz-le, quercetin and spegazzinine also occurred. 6. The ATPase of glycerol-grown cells was less sensitive to inhibitors than that of glucose-repressed cells; change in values for I50 were not so marked during the growth cycle of cells growing with glycerol. 7. When submitochondrial particles from glycerol-grown cells were tested by passage through Sephadex G-50, a fourfold increase in activity was accompanied by increased inhibitor resistance. 8. Gel filtration of submitochondrial particles from glucose-de-repressed cells gave similar results, whereas loss of ATPase occurred in submitochondrial particles from glucose-repressed cells. 9. It is proposed that alterations in sensitivity to inhibitors at different stages of glucose derepression may be partly controlled by a naturally occuring inhibitor of ATPase. 10. The inhibitors tested may be classififed into two groups on the basis of alterations of sensitivity of the ATPase during physiological modification: (a) oligomycin, Dio-9, NN'-dicyclohexylcarbodi-imide, venturicidin and triethyltin, and (b) efrapeptin, aurovertin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin and spegazzinine.

Adenosine Triphosphatases↗
PubMed1977

Ethacrynic acid inhibitable Ca2+ and Mg2+-activated membrane adenosine triphosphatase in rat mast cells.

A crude plasma membrane fraction from the homogenate of purified rat mast cells demonstrates a high degree of Ca2+-dependent and Mg2+-dependent adenosine triphosphatase (ATPase) activity. The microsomal and mitochondrial fractions show negligible amounts of the Ca2+ and Mg2+-activated ATPases. The broad ATPase inhibitor, ethacrynic acid, effectively blocks the mast cell ATPase activity while ouabain demonstrates little inhibitory effect. Correspondingly, ethacrynic acid inhibits histamine release from antigen-challenged mast cells while ouabain does not. Both ATPase inhibition and histamine release inhibition by ethacrynic acid require the presence of the olefinic bond in the ethacrynic acid molecule.

Adenosine Triphosphatases↗
PubMed1978

Adenosine triphosphatase activities in Trypanosoma cruzi.

1. Subcellular fractions obtained from epimastigotes of Trypanosoma cruzi, disrupted by three different procedures, contained in addition to the already known Mg2+-activated adenosine triphosphatase (ATPase; E.C.3.6.1.4), a Ca2+-ATPase activity. 2. The Ca2+-ATPase (a) was activated by low concentrations of CaCl2 (apparent Ka, 80 microM); (b) had a Km for ATP of 0.6 mM (at 1 mM CaCl2, pH 8.0); (c) presented a broad pH curve (optimum 7.1-8.6); and (d) was insensitive to oligomycin concentrations which inhibited the Mg2+-ATPase present in the same preparations. 3. All attempts to find a (Na+-K+)-activated, ouabain-inhibited, ATPase have been unsuccessful, in spite of the fact that living epimastigoes of T. cruzi are able to concentrate K+ and exclude Na+ from the medium.

Adenosine Triphosphatases↗
PubMed1994

[The cytochemical determination of alpha-glycerophosphate dehydrogenase and adenosine triphosphatase in the peripheral blood lymphocytes of patients with hepatobiliary system pathology].

In patients with pancreatic head cancer and virus hepatitis the lowest values of alpha glycerophosphate dehydrogenase and adenosine triphosphatase in the peripheric blood lymphocytes were determined. The dynamic study of these values in patients with pathology of liver and biliary ducts permits to estimate the disease severity course and equally with other clinico-laboratory data may have prognostic significance.

Adenosine Triphosphatases↗
PubMed1989

The effect of spermine, spermidine and kallikrein on the triple adenosine triphosphatase enzyme activity of spermatozoa in males with oligoasthenozoospermia.

Unknown factors in the seminal plasma of normal semen that affect the motility of spermatozoa have a positive effect on adenosine triphosphatase (ATPase) enzyme activity. In an attempt to produce such an effect, spermine, spermidine and kallikrein were added to the incubation media in which spermatozoal ATPase enzyme activity was determined. These seminal substances increased the triple ATPase enzyme activity of spermatozoa from oligoasthenozoospermic men. We propose that the ATPase enzyme activity of spermatozoa may indicate sperm motility as a biochemical test.

Adenosine Triphosphatases↗
PubMed1974

Membrane adenosine triphosphatase of Micrococcus lysodeikticus: effect of millimolar Mg2+ in modulating the properties of the membrane-bound enzyme.

The latency of Micrococcus lysodeikticus membrane-bound Mg(2+)-adenosine triphosphatase (ATPase) is expressed by the ratio of its activity assayed in the presence of trypsin ("total") versus the activity assayed in absence of the protease ("basal"). By isolating membranes in the presence of variable concentrations of Mg(2+) (50 mM, 10 mM, or none) and by washing them with different Mg(2+)- and ethylenediaminetetraacetic acid-containing tris(hydroxymethyl)aminomethane-hydrochloride buffers (pH 7.5), we showed that the enzyme latency was dependent on the environmental concentration of this divalent metal ion. Mg(2+) bound to at least two classes of sites. The binding of Mg(2+) to low-affinity sites (saturation at approximately 40 mM external Mg(2+)) induced a high basal ATPase activity, whereas its binding to medium-affinity sites (saturation at about 2 mM Mg(2+)) correlated with low basal activity and a very high stimulation by trypsin. Membranes with tightly bound Mg(2+) (high affinity?) revealed an intermediate behavior for the latency of M. lysodeikticus ATPase. The Mg(2+)/Ca(2+) antagonism as activators of the membrane ATPase was not directly related to Mg(2+) binding by the membranes. The efficiency of the ATPase release from M. lysodeikticus membrane by 3 mM tris(hydroxymethyl)aminomethane-hydrochloride buffer (pH 7.5) was inversely proportional to the concentration of external and/or bound Mg(2+). Deoxycholate (DOC) (1%) solubilized the ATPase from all types of membrane. All the soluble ATPases behaved as Ca(2+)-ATPases, but the DOC-soluble fractions showed degrees of latency like those of the original membranes. The DOC-soluble ATPase preparation revealed a vesicular structure and complex protein patterns by sodium dodecyl sulfate gel electrophoresis. We propose that ATPase latency is modulated via a Mg(2+)-ATPase-membrane complex.

Adenosine Triphosphatases↗
PubMed1976

Dependence of renal (Na+ + k+)-adenosine triphosphatase activity on thyroid status.

In thyroidectomized rats, a single injection of L-2,,5,2'-triiodothyronine (T3) (50mug/100 g body weight) elicited at 45% increase in (Na+ + k+)-dependent adenosine triphosphatase (NaK-ATPase) activity of the membrane-rich fraction of renal cortex at the optimal time of response, 48 h after injection. Three successive doses of T3 (50 mug/100 g body weight), given on alternate days, increased NaK-ATPase by 67% in the renal cortex but had no significant effect on the outer medulla or the papilla. Moreover, T3 had no effect on Mg2+-dependent adenosine trisphatase (MgATPase) in cortex, cedulla, or papilla. Three doses of T3 (50 mug/100 g body weight) given on alternate days to thyroidectomized rats elecited a 134, 79, and 46% increase in Vmax for ATP, Na4, and K+, respectively. There were no changes in the Km for ATP or the K1/2 values for Na+ and K+. Two methods were used to estimate the effect of T3 on the number of NaK-ATPase units (assumed to represent the number of Na+ pump sites); rat renal plasma membrane fractions were incubated with [gamma-32P]ATP, Mg2+, and Na+; the 32P-labeled membrane protein yeild was quantitatively dependent on Na+ and was hydrolyzed on addition of K+. There was a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of phosphorylated intermediate formed, in renal cortical membrane fractions from thyroidectomized rats given T3 or the diluent. There was also a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of [3H]ouabain specifically bound (Na+-, Mg2+-, APT-dependent) to the NaK-ATPase preparation. Injection of T3 resulted in a 70% increase in NaK-ATPase activity, a 79% increase in formation of the phosphorylated intermediate, and a 65% increase in the [H]ouabain specifically bound to the NaK-ATPase system. The T3-dependent increases in Vmax for ATP, Na+, and K+ and the proportionate increases in the phosphorylated intermediate and in the amount of [3H]ouabain bound indicate that T3 increases the number of NaK-ATPase units and that this increase accounts for the increase in NaK-ATPase activity.

Adenosine Triphosphatases↗
PubMed1976

Effect of uncoupler on "downhill" substrate efflux of Escherichia coli is dependent on (Mg2+, Ca2+). Adenosine triphosphatase.

Previous studies have shown that mutations in the unc gene of Escherichia coli K12 cause defects in energy transduction as well as a membrane-bound (Mg2+, Ca2+)-adenosine triphosphatase. We studied the effect of this mutation on the "downhill" efflux of methyl-beta-D-galactopyranoside, a suboli K12 did not show significant differences in substrate influx of efflux, a differential effect of an uncoupler, 2,4-dinitrophenol was demonstrated. In contrast to the unc+, dinitrophenol failed to inhibit significantly the rate coefficient of efflux in the unc- strain. Analysis of spontaneous unc+ revertants of the unc- mutant provided additional evidence that a functional unc gene is necessary for dinitrophenol inhibition of efflux. Other uncouplers tested in the unc+ strain showed different effects on efflux. While arsenate, azide and carbonyl cyanide p-trifluoromethoxyphenulhydrazone caused little or no effect, 2,4-dibromophenol and pentachlorophenol increased efflux by a considerable factor.

Adenosine Triphosphatases↗
PubMed1977

On the mechanism of sodium- and potassium-activated adenosine triphosphatase. Time course of intermediary steps examined by computer simulation of transient kinetics.

In order to learn whether the kinetics of transient phosphorylation of sodium plus potassium ion transport adenosine triphosphatase was compatible with the hydrolysis of ATP, computer simulation of experimental data was studied. The enzyme mechanism was described in terms of first order and pseudo-first order reactions. The resulting system of linear first order differential equations was solved by a Runge-Kutta method. Phosphorylation kinetics was studied by means of a rapid mixing apparatus at 21 degrees in the presence of 100 micron ATP, 3 mM MgCl2, 120 mM NaCl, and 10 mM KCl. Computer simulation gave a close fit to experimental data with a model of the reaction mechanism which included a sequence of two dephospho forms and two phospho forms of the enzyme. With this model, rate constants obtained by computer simulation were in agreement with constants which had been determined in separate phosphorylation and dephosphorylation experiments. Within experimental limits, the net flux of reaction in each partial step was compatible with the (Na+,K+)-stimulated hydrolysis of ATP (about 324 and 300 nmol-mg-1-min-1, respectively).

Adenosine Triphosphatases↗
PubMed1978

Reaction mechanism of the magnesium ion-dependent adenosine triphosphatase of frog muscle myosin and subfragment 1.

The Mg2+-dependent ATPase (adenosine 5'-triphosphatase) mechanism of myosin and subfragment 1 prepared from frog leg muscle was investigated by transient kinetic technique. The results show that in general terms the mechanism is similar to that of the rabbit skeletal-muscle myosin ATPase. During subfragment-1 ATPase activity at 0-5 degrees C pH 7.0 and I0.15, the predominant component of the steady-state intermediate is a subfragment-1-products complex (E.ADP.Pi). Binary subfragment-1-ATP (E.ATP) and subfragment-1-ADP (E.ADP) complexes are the other main components of the steady-state intermediate, the relative concentrations of the three components E.ATP, E.ADP.Pi and E.ADP being 5.5:92.5:2.0 respectively. The frog myosin ATPase mechanism is distinguished from that of the rabbit at 0-5 degrees C by the low steady-state concentrations of E.ATP and E.ADP relative to that of E.ADP.Pi and can be described by: E + ATP k' + 1 in equilibrium k' - 1 E.ATP k' + 2 in equilibrium k' - 2 E.ADP.Pi k' + 3 in equilibrium k' - 3 E.ADP + Pi k' + 4 in equilibrium k' - 4 E + ADP. In the above conditions successive forward rate constants have values: k' + 1, 1.1 X 10(5)M-1.S-1; k' + 2 greater than 5s-1; k' + 3, 0.011 s-1; k' + 4, 0.5 s-1; k'-1 is probably less than 0.006s-1. The observed second-order rate constants of the association of actin to subfragment 1 and of ATP-induced dissociation of the actin-subfragment-1 complex are 5.5 X 10(4) M-1.S-1 and 7.4 X 10(5) M-1.S-1 respectively at 2-5 degrees C and pH 7.0. The physiological implications of these results are discussed.

Actins↗
PubMed2003

Expression of copper-transporting P-type adenosine triphosphatase in human esophageal carcinoma.

A major obstacle in the treatment of esophageal carcinoma is the intrinsic/acquired resistance to cisplatin-based chemotherapy. Copper-transporting P-type adenosine triphosphatase (ATP7B) has been reported to be associated with cisplatin resistance in vitro. However, the clinical significance of this transporter has not previously been addressed. Our goal was to investigate if ATP7B is expressed in esophageal carcinoma and whether its expression correlates with reduced responsiveness to cisplatin treatment. We retrospectively examined the expression of ATP7B in primary esophageal carcinoma and its association with chemotherapeutic effect. Tissues were surgically removed from 17 esophageal carcinoma patients. Twelve of them received cisplatin-based chemotherapy before surgery. We performed immunohistochemical analysis of ATP7B using a monoclonal antibody against ATP7B in 17 esophageal carcinomas. A variable degree of cytoplasmic staining of tumor cells was observed in 76.5% (13/17 cases) of the analyzed carcinomas. ATP7B expression was not observed in adjacent non-neoplastic tissues. ATP7B positivity was not significant in gender, age, histopathological grading or TNM categories. Patients with ATP7B-positive tumors tended to have an inferior response to chemotherapy compared with the patients with ATP7B-negative tumors. These findings suggest that overexpression of ATP7B in esophageal carcinoma could be associated with unfavorable clinical outcome in patients treated with cisplatin-based chemotherapy. Therefore, ATP7B gene expression might be considered as a chemoresistance marker for cisplatin in the patients of esophageal carcinoma and provider of important information on the strategy against esophageal carcinoma.

Adenosine Triphosphatases↗
PubMed1976

Sodium- and potassium-activated adenosine triphosphatase of the nasal salt gland of the duck (Anas platyrhynchos). Purification, characterization, and NH2-terminal amino acid sequence of the phosphorylating polypeptide.

Sodium- and potassium-activated adenosine triphosphatase (NaK-ATPase) was purified from nasal salt glands of the duck (Anas platyrhynchos). Enzyme of specific activity 2,000 to 2,300 mumol of Pi/mg/hour was routinely obtained by sodium dodecyl sulfate treatment of a microsomal fraction of gland homogenate in the presence of 3 mM ATP followed by pelleting of the enzyme through a sucrose density gradient. Purified NaK-ATPase was stable for over 3 months at -20 degree. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography purified NaK-ATPase was shown to contain two polypeptide chains of molecular weight 94,000 and 60,000, the smaller of which was a glycoprotein. Purified enzyme of activity 2,300 mumol of Pi/mg/hour bound 3,600 pmol of ouabain/mg of enzyme protein. Reaction with [gamma-32P]ATP in the presence of Mg2+ and Na+ gave 7,025 pmol of acyl phosphate/mg of enzyme protein. The turnover number calculated from phosphorylation data was 5,460 min-1. Amino acid analysis of the polypeptide components of duck salt gland enzyme after separation by gel filtration chromatography in sodium dodecyl sulfate demonstrated strong compositional homology with highly purified NaK-ATPase preparations from other organs and species. The NH2-terminal amino acid of the 94,000-dalton component was glycine and of the 60,000-dalton component, alanine. With a combination of manual sequencing and automated Edman degradation, the NH2-terminal amino acid sequence of the 94,00-dalton catalytic subunit was found to be Gly-Arg-Asn-Lys-Tyr-Glu-Thr-Thr-Ala-()-Ser-Glu.

Adenosine Triphosphatases↗
PubMed1985

Inhibitory action of morphine on adenosine triphosphatase content in the whole and individual nuclei of mouse brain during the tolerance-dependence development and its reversal by naloxone.

Fluctuations in the content and distribution of adenosine triphosphatase in the brain of mice during the period of morphine tolerance-dependence development as well as normal and and naloxone induced withdrawal have been studied. The histochemical investigation revealed the enzyme activity in the neurons, neuroglia and blood vessels. In the control animals the nucleus caudatus putamen, globus pallidus, hippocampus, nuclei of amygdala, nuclei hypothalami, substantia grisea centralis, griseum pontis, nucleus trapezoideus, nucleus prepositus hypoglossi, nucleus parabrachialis, nucleus vestibularis, nucleus nervi hypoglossi, nucleus dorsalis nervi vagi, nucleus olivaris and nucleus centralis superior are found to be very rich in ATPase. However, morphine treatment inhibited the enzyme in all the above nuclei and it was linear with the increase in dose and the duration of the treatment. Cytophotometric studies reveal that the differences in the enzymatic activity varies from nuclei to nuclei. Surprisingly enough, normal withdrawal as well as naloxone induced withdrawal significantly elevated the enzyme levels. All above findings have been confirmed biochemically. The study gives a firm support of the earlier finding that morphine inhibits ATPase. In addition to this, the present work also reveals a direct antagonistic effect of naloxone on the content of the enzyme in the morphine treated animals. This suggests that the observed inhibition of the enzyme is narcotic specific. The role of ATPase in the Na+, K+ transport is discussed with respect to morphine action. In the light of the present investigation, the effect of morphine on the neurotransmitter release, and the cause and effect there upon has been analyzed. It has been suggested that ATPase might be the enzyme responsible for the observed pharmacological responses of the neurons to the application of the drug by affecting the Na+, K+ flux and neurotransmitter release.

Adenosine Triphosphatases↗