Inhibition of dog kidney Na+, K+-ATPase activity by procaine, tetracaine and dibucaine

P-type ATPases as drug targets: tools for medicine and science

P-type ATPases catalyze the selective active transport of ions like H+, Na+, K+, Ca2+, Zn2+, and Cu2+ across diverse biological membrane systems. Many members of the P-type ATPase protein family, such as the Na+,K+-, H+,K+-, Ca2+-, and H+-ATPases, are involved in the development of pathophysiological conditions or provide critical function to pathogens. Therefore, they seem to be promising targets for future drugs and novel antifungal agents and herbicides. Here, we review the current knowledge about P-type ATPase inhibitors and their present use as tools in science, medicine, and biotechnology. Recent structural information on a variety of P-type ATPase family members signifies that all P-type ATPases can be expected to share a similar basic structure and a similar basic machinery of ion transport. The ion transport pathway crossing the membrane lipid bilayer is constructed of two access channels leading from either side of the membrane to the ion binding sites at a central cavity. The selective opening and closure of the access channels allows vectorial access/release of ions from the binding sites. Recent structural information along with new homology modeling of diverse P-type ATPases in complex with known ligands demonstrate that the most proficient way for the development of efficient and selective drugs is to target their ion transport pathway.

Nitric Oxide Production by the Vacuolar-Type (H+)-ATPase Inhibitors Bafilomycin A1 and Concanamycin A and Its Possible Role in Apoptosis in RAW 264.7 Cells

In the mouse leukemic monocyte cell line RAW 264.7, the vacuolar-type (H(+))-ATPase (V-ATPase) inhibitors bafilomycin A1 and concanamycin A induced nitric oxide (NO) production through the expression of inducible nitric-oxide synthase mRNA and its protein and decreased cell growth and survival as determined by 3-(4,5-dimethyl(thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Bafilomycin A1 and concanamycin A activated nuclear factor (NF)-kappaB and activator protein-1 and decreased the level of IkappaB-alpha and increased that of phosphorylated c-Jun N-terminal kinase (JNK). NO production induced by these V-ATPase inhibitors was suppressed by the NF-kappaB inhibitor Bay 11-7082 [(E)3-[(4-methylphenyl)sulfonyl])-2-propenenitrile] and the JNK inhibitor SP600125 [anthra[1,9-cd]pyrazol-6(2H)-one] in parallel with the partial alleviation of the V-ATPase inhibitor-induced decrease in MTT response. The Na(+),K(+)-ATPase inhibitor dibucaine and the F-ATPase inhibitor oligomycin did not induce NO production at which concentrations the MTT response was decreased. The NO donor S-nitroso-N-acetyl-dl-penicillamine further lowered the V-ATPase inhibitor-induced decrease in the MTT response, and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, sodium salt (carboxy-PTIO) alleviated it partially. Mitochondrial depolarization, an index of apoptosis, was induced by bafilomycin A1 and concanamycin A. On treatment with the nitric-oxide synthase inhibitor N(G)-monomethyl-l-arginine acetate, the disruption of mitochondrial membrane potential induced by bafilomycin A1 and concanamycin A was alleviated partially in parallel with the decrease in NO production. Carboxy-PTIO also alleviated it partially. Our findings suggest that the V-ATPase inhibitors bafilomycin A1 and concanamycin A similarly induce NO production and the newly produced NO participates partially in the V-ATPase inhibitor-induced apoptosis in RAW 264.7 cells.

A study of the perturbation effects of the local anesthetic procaine on human erythrocyte and model membranes and of modifications of the sodium transport in toad skin

The interaction of the local anesthetic procaine with human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), isolated toad skins, and molecular models is described. The latter consisted of phospholipid multilayers built-up of dimyristoylphosphatidylcholine (DMPC) and of dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Optical and scanning electron microscopy of human erythrocytes revealed that procaine induced the formation of stomatocytes. Experiments performed on IUM at 37 degrees C by fluorescence spectroscopy showed that procaine interacted with the phospholipid bilayer polar groups but not with the hydrophobic acyl chains. X-ray diffraction indicated that procaine perturbed DMPC structure to a higher extent when compared with DMPE, its polar head region being more affected. Electrophysiological measurements disclosed a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of procaine to isolated toad skin, reflecting inhibition of active ion transport.

The tertiary amine local anesthetic dibucaine binds to the membrane skeletal protein spectrin

The quinoline-based tertiary amine dibucaine has been shown to bind the membrane skeletal protein spectrin with a dissociation constant of 3.5x10(-5) M at 25 degrees C. Such binding is detected by monitoring the quenching of the tryptophan fluorescence intensity with increasing concentrations of dibucaine only and not with the benzene-based local anesthetics procaine, tetracaine and lidocaine. Binding of dibucaine also indicated changes in the tertiary structure of spectrin indicated by a circular dichroism spectrum in the near-UV region due to absorption of the aromatic side chains. The thermodynamic parameters associated with the binding indicated the interaction of dibucaine and spectrin to be enthalpy-driven and insensitive to an increase in the ionic strength of the buffer.

Effect of cinnamon, clove and some of their constituents on the Na(+)-K(+)-ATPase activity and alanine absorption in the rat jejunum

The effect of a water extract of some spices on the in vitro activity of the rat jejunal Na(+)-K(+)-ATPase was investigated. Extracts of nutmeg, cinnamon, clove, cumin, coriander, turmeric and caraway all inhibited the ATPase, while anise seed and white pepper exerted no significant effects. The extracts of clove and cinnamon had the most potent inhibitory effect on the intestinal ATPase as compared to extracts of other spices. They also inhibited the in vitro Na(+)-K(+)-ATPase activity in a crude kidney homogenate and the activity of an isolated dog kidney Na(+)-K(+)-ATPase. The alcoholic extract of cinnamon, compared to the aqueous extract, had a stronger inhibitory action on the jejunal enzyme and a lower IC(50) value, which was not significantly different from the one observed with cinnamaldehyde, the major volatile oil present cinnamon, suggesting that in alcoholic extracts cinnamaldehyde is the major inhibitory component. The IC(50) values of eugenol, aqueous clove extract and ethanolic clove extract all fell within the same range and were not significantly different from each other, suggesting that eugenol is the major inhibitory component in both alcoholic and aqueous extracts. Based on the IC(50) values, the order of sensitivity of the enzyme to the spices extracts is as follows: isolated dog kidney ATPase>rat kidney ATPase>rat intestine ATPase. The aqueous extracts of clove and cinnamon also significantly lowered the absorption of alanine from the rat intestine. It was concluded that the active principle(s) in clove and cinnamon can permeate the membrane of the enterocytes and inhibit the Na(+)-K(+)-ATPase that provides the driving force for many transport processes.

Changes in erythrocyte membrane ATPases and plasma lipid peroxides in upper abdominal surgery under intravenous procaine-balanced anesthesia

AIM: To observe the changes in erythrocyte membrane ATPases and plasma lipid peroxides (LPO) patients with in abdominal surgery under intravenous procaine balanced anesthesia.

METHODS: By determining the ATPase activities of erythrocyte membrane, effects of upper abdominal surgery under intravenous procaine-balanced anesthesia on the function of erythrocytes were observed in 15 patients undergoing cholecystectomy and gastrectomy (5 males and 10 females, aged 45.9 ± 10.20 years and weighed 60.60 kg ± 11.93 kg). All patients were free from severe renal,hepatic, pulmonary, cardiac, metabolic and endocrinological diseases and acute infection for at least 2 weeks before surgery. Patients receiving any drug known to affect carbohydrate metabolism prior to anesthesia were excluded from the study.

RESULTS: Erythrocyte membrane Na⁺, K⁺-ATPase, Mg²⁺-ATPase, Ca²⁺, Mg²⁺-ATPase activities were not significantly changed 60 min-90 min after incision as compared with 30min before anesthesia, but were decreased markedly 10min and 24 h after completion of operation (P ＜ 0.01). Plasma lipid peroxides (LPO) were increased significantly 24 h after surgery (P ＜ 0.01) following an initially marked but transient reduction. Plasma LPO changes were not correlated with erythrocyte membrane ATPase activities, r = -0.0396, -0.0097 and 0.4383, respectively (P ＞ 0.05).

CONCLUSION: Abdominal surgical trauma under intravenous procaine-balanced anesthesia may be associated with the decreased ATPase activities of erythrocyte membrane and increased LPO in plasma.

Spin label study of the perturbation effect of the local anaesthetics tetracaine and dibucaine on synaptosomes at pharmacological concentrations

The method of electron spin resonance spectroscopy of spin probes was used to determine the lowest concentrations of the local anaesthetics dibucaine and tetracaine exerting perturbations on synaptosome membranes. The perturbation depends on the temperature and the membrane depth, as well as on the concentration and the structure of the anaesthetics. Using spin labelled stearic acid at the 5th carbon position a negligible effect of the anaesthetics on the order parameter was found in the membrane both at 1 degree and 22 degrees, within the buffer concentration 0.01-10 mmol/l, but at 37 degrees and concentrations higher than 0.1 mmol/l the disordering effect was significant and of comparable efficiency for dibucaine and tetracaine. Employing stearic acid labelled at the 16th carbon position, disordering of the hydrocarbon core of the membrane caused by tetracaine or dibucaine was detected at 1 degree and 22 degrees, as well as at 37 degrees. The disordering effect occurred at buffer concentrations higher than 0.01 mmol/l for dibucaine, and higher than 0.1 mmol/l for tetracaine. At equal anaesthetic membrane concentrations and at the 16th carbon membrane depth, dibucaine was approximately twice as effective as tetracaine in perturbing synaptosomes. Tetracaine induced nonlamellar phases in the rat brain lipid membrane as detected by 31P NMR spectroscopy. The dynamic and structural perturbation effects of the local anaesthetics was found in that concentration range at which the anaesthetics influence various activities of biological membranes.

NMR investigation of the influence of procaine and its metabolites on the water exchange through human erythrocyte membranes

The effect of procaine hydrochloride and its metabolites on the diffusional water exchange through erythrocyte membranes was investigated at 37 degrees C and at concentrations ranging between 5 X 10(-5) M and 5 X 10(-1) M by using the NMR manganese doping method. Procaine hydrochloride and 2-diethylaminoethanol have a moderate stimulating effect on the water exchange, of up to 20% at concentrations ranging between 10(-3) and 10(-2) M, while an increasing inhibitory effect was found at higher concentrations. The p-aminobenzoic acid has no effect on the water exchange up to 10(-2) M and, at higher concentrations, and apparent decreasing inhibition was noticed which is thought to be an artefact due to the uptake of Mn2+ by the cells. The temperature dependence studies suggest that procaine HCl enhances the uptake of Mn2+ by the cells. An opposite effect was found for rigid erythrocytes. The p-aminobenzoic acid and 2-diethylaminoethanol appeared to be more effective than procaine hydrochloride in increasing the uptake of Mn2+.