Pentagalloylglucose, an antisecretory component of Paeoniae radix, inhibits gastric H+, K(+)-ATPase.

We purified a compound with strong inhibitory effect on H+, K(+)-ATPase from Paeoniae radix, which has been used in Japan for the treatment of gastritis and peptic ulcers. The compound was identified as 1,2,3,4,6,-penta-o-galloyl-beta-D-glucose by proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, and fast atomic bombardment mass spectrometry. The IC50 of the compound for H+, K(+)-ATPase was 166 nmol/l. Kinetic analyses indicated that the inhibition of the enzyme by pentagalloylglucose was noncompetitive with respect to K+. Pentagalloylglucose had relatively weak inhibitory effects for Mg(+)-ATPase (IC50: > 10 mumol/l) and Na+, K(+)-ATPase (IC50: 2.7 mumol/l). Pentagalloylglucose also inhibited the accumulation of [14C]aminopyrine in parietal cells that had been isolated from guinea pig stomach and stimulated by 10 mumol/l histamine (IC50: 7.8 mumol/l) and 1 mmol/l dbc-AMP (IC50: 10 mumol/l). These results suggest that pentagalloylglucose is a potent inhibitor of H+, K(+)-ATPase and may be responsible for inhibition of acid secretion by Paeoniae radix.

Responsiveness of beta-escin-permeabilized rabbit gastric gland model: effects of functional peptide fragments.

We established a beta-escin-permeabilized gland model with the use of rabbit isolated gastric glands. The glands retained an ability to secrete acid, monitored by [14C]aminopyrine accumulation, in response to cAMP, forskolin, and histamine. These responses were all inhibited by cAMP-dependent protein kinase inhibitory peptide. Myosin light-chain kinase inhibitory peptide also suppressed aminopyrine accumulation, whereas the inhibitory peptide of protein kinase C or that of calmodulin kinase II was without effect. Guanosine-5'-O-(3-thiotriphosphate) (GTPgammaS) abolished cAMP-stimulated acid secretion concomitantly, interfering with the redistribution of H+-K+-ATPase from tubulovesicles to the apical membrane. To identify the targets of GTPgammaS, effects of peptide fragments of certain GTP-binding proteins were examined. Although none of the peptides related to Rab proteins showed any effect, the inhibitory peptide of Arf protein inhibited cAMP-stimulated secretion. These results demonstrate that our new model, the beta-escin-permeabilized gland, allows the introduction of relatively large molecules, e.g., peptides, into the cell, and will be quite useful for analyzing signal transduction of parietal cell function.

In vivo metabolism of aminopyrine by the larvae of the helminth Heligmosomoides polygyrus.

The in vivo N-dealkylation of [13C-2]-labeled aminopyrine by the L1-L2 larvae of Heligmosomoides polygyrus was demonstrated by the use of a sensitive gas chromatography-mass spectrometry method. This is the first evidence for the possible existence of a cytochrome P-450-dependent activity in helminths.

[Effects of analgesic-antipyretics on the spinal reflex potentials in cats: an analysis of the excitatory action of aminopyrine].

The effects of some analgesic-antipyretics on the spinal reflex potentials were studied in spinal cats. Aminopyrine at 25-100 mg/kg, i.v. produced a marked increase in mono- and poly-synaptic reflex potentials (MSR and PSR), and a decrease in dorsal root reflex potentials (DRR) in a dose-dependent manner. The amplitude of DRR decreased by aminopyrine was reversed by diazepam at 0.2 mg/kg, i.v.; however, the increased amplitudes of MSR and PSR were not affected by diazepam. Pretreatment of semicarbazide at 200 mg/kg, i.v. did not influence the increasing effect of aminopyrine on MSR and PSR. DL-5-Hydroxytryptophan produced facilitation of the MSR and PSR. In DL-5-hydroxytryptophan-treated cats, the amplitude of MSR was further increased by aminopyrine. Methysergide at 1 mg/kg, i.v. antagonized this increasing effect of aminopyrine on MSR and PSR. These observations suggest that the excitatory action of aminopyrine may be partly related to 5-hydroxytryptamine and not connected to the GABAergic mechanism. Other pyrazolone derivatives were also studied. Isopropylantipyrine at 50 mg/kg, i.v. produced increases in MSR and PSR. Intravenous sulpyrine at 500 mg/kg, antipyrine at 50 mg/kg or 4-aminoantipyrine at 50 mg/kg did not affect the reflex potentials. The non-pyrazolones, acetaminophen and indomethacin, did not increase the MSR and PSR. These results suggest that the N-dimethyl or isopropyl residue at the 4 position of the pyrazolone structure plays an important role in the excitatory action of analgesic-antipyretics in cat spinal cord.

Pharmacological characterization of histamine H3 receptors in isolated rabbit gastric glands.

The effects of the specific H3 agonist (R)-alpha-methylhistamine (alpha-MeHA) and the specific H3 antagonist thioperamide were examined on histamine release and acid secretion [( 14C]-aminopyrine (AP) accumulation) by isolated rabbit gastric glands. Thioperamide significantly enhanced basal histamine release from the glands (+50% at 30 min for 10(-7) M thioperamide; P less than 0.01), and this increase was prevented by alpha-MeHA. Histamine-elicited AP accumulation was increased by 18% (P less than 0.05) by 10(-7) M thioperamide and decreased by 70% (P less than 0.01) by 10(-6) M of the H2 antagonist ranitidine. Thioperamide alone significantly enhanced AP accumulation in a dose-dependent manner, whereas alpha-MeHA had no effect of its own on this accumulation. Thioperamide stimulation of basal AP accumulation was not modified by ranitidine but was 50% decreased by alpha-MeHA. Furthermore, carbachol-induced AP accumulation was decreased by alpha-MeHA and increased by thioperamide; the latter effect was not blocked by ranitidine. These findings support that H3 receptors pharmacologically distinct from H2 receptors are involved in the regulation of histamine-stimulated acid secretion. They further suggest that these gastric H3 receptors occur in the gastric glands as 1) H3 autoreceptors located on the histamine-secreting cells and acting to downregulate histamine release from these cells and 2) H3 (or H3-like) receptors located on the parietal cell and regulating in a negative manner the acid secretory process.

[The action of inhibitors of the amine nitrosation reaction in human gastric juice and in the body of animals]. / Deistvie ingibitorov reaktsii nirtrozirovaniia aminov v zheludochnom soke cheloveka i v organizme zhivotnykh.

The effect of ascorbic, ferulic and caffeic acids on dimethylamine and amidopyrine nitrosation in a medium containing 3 samples of total gastric juice taken from 10 humans (pH = 6.1; 3.2 and 1.7) was studied versus the amount of inhibitor added to the medium. The resultant relationship proved bizarre, the inhibitor at low concentrations stimulating nitrosation in some situations. When gastric juice concentration in the medium was further lowered by dilution with a buffer at relevant value of pH, the paradoxical effect of inhibition gradually disappeared.

Protective action of ascorbic acid against mutagenicity of aminopyrine plus nitrite.

Mutagenicity of aminopyrine and of aminopyrine plus nitrite was tested by the micronucleus test in bone marrow of mice and by host mediated mutagenicity assay with mice as host animals and S. typhimurium strain G 46. In parallel the possibility of the protective action of ascorbic acid was studied. Aminopyrine at the dose of 90 mg/kg po when administered to mice together with potassium nitrite induced a significant increase in the frequency of micronuclei in polychromatic erythrocytes and proved to be mutagenic for a Salmonella strain. In both systems mutagenicity of the combination of aminopyrine at this dose plus nitrite was abolished completely by ascorbic acid (373 or 622 mg/kg po). Ascorbic acid neither induced a significant increase in the frequency of micronuclei nor was mutagenic for the strain G 46. A formulation of aminopyrine with ascorbic acid is proposed.

Lack of inhibition of clomethiazole metabolism by cimetidine: model experiments in the dog.

The disposition of clomethiazole was studied in six dogs subjected to pretreatment with cimetidine or saline according to a cross-over design. Pretreated dogs received approximately 20 mg/kg of cimetidine p.o. for 4 days and 30 mg/kg i.v. immediately before an intraduodenal infusion of clomethiazole (117 mumol/kg clomethiazole base within 90 min). Compared to controls, cimetidine had no effect on peak plasma concentrations and on areas under the plasma concentration time curves of clomethiazole or of its metabolite 5-acetyl-4-methylthiazole (P greater than 0.05). Identical pretreatment of the same dogs resulted in a 50% inhibition of aminopyrine demethylation (P less than 0.001) as revealed by the aminopyrine breath test. Clomethiazole may be metabolized in the dog through metabolic routes which cannot be inhibited by cimetidine.

Extracellular calcium and cholinergic stimulation of isolated canine parietal cells.

The role of calcium gating in cholinergic stimulation of the function of parietal cells was studied using cells isolated from canine fundic mucosa by treatment with collagenase and EDTA and enriched by velocity separation in an elutriator rotor. Monitoring the accumulation of [14C[ aminopyrine as an index of parietal cell response, stimulation by carbachol, but not by histamine, was highly dependent upon the concentration of extracellular calcium. Incubation of parietal cells in 0-.1 mM calcium, rather than the usual 1.8 mM concentration, reduced the response to 100 microM carbachol by 92 +/- 2%, whereas histamine stimulation was impaired by 28 +/- 5%. A similar reduction in extracellular calcium suppressed the response to gastrin (100 nM) by 67 +/- 7%. The impairment of cholinergic stimulation found at low extracellular calcium concentrations was rapidly reversed with the readdition of calcium. Lanthanum, which blocks calcium movement across membranes, caused a similar pattern of effects on secretagogue stimulation of aminopyrine accumulation, with 100 microM lanthanum suppressing carbachol stimulation by 83 +/- 2%. This concentration of lanthanum suppressed gastrin stimulation by 40 +/- 7% and histamine stimulation by only 12 +/- 9%. Carbachol, but not histamine nor gastrin, stimulated 45Ca++ uptake. The magnitude of carbachol-stimulated calcium uptake correlated with the parietal cell content of the fractions examined (r = 0.88), and was dose responsive over carbachol concentrations from 1 microM to 1 mM. Atropine (100 nM) caused surmountable inhibition, and these effects of carbachol and atropine on calcium uptake correlated with their effects on oxygen consumption (r = 0.93) and [14C]-aminopyrine accumulation (r = 0.90). Cells preloaded with 45Ca++ lost cellular calcium in a time-dependent fashion; however, this rate of egress was not accelerated by treatment with histamine, gastrin, or carbachol, thus failing to implicate mobilization of intracellular calcium as primary mechanism for activation of parietal cell function. These data indicate a close link between stimulation of parietal cell function and enhancement of calcium influx by cholinergic agents.

The effect of ascorbic acid on the amine-nitrite and nitrosamine mutagenicity in bacteria injected into mice.

Ascorbic acid was tested for its ability to increase or decrease the induction of bacterial mutations by dimethylnitrosamine (DMN) or aminopyrine plus nitrite within intact mice. No evidence was found of the mutagenicity of ascorbic acid itself when tested alone or in the presence of copper ions. Similarly, no increase or decrease in the DMN-induced mutation frequency was observed. However, ascorbic acid was found to decrease the aminopyrine/nitrite-induced mutation frequency to an extent which was dependent on the experimental conditions used.

Blockade by l-lysine of non-narcotic analgesics.

The antinociceptive effects of the non-narcotic analgesics clonixin, flunixin, acetylsalicylic acid, aminopyrine and phenylbutazone in the yeast paw test were blocked by l-lysine. Blockade occurred at doses of l-lysine which did not affect pain threshold. The site(s) or mechanism of action of blockade could not be determined with certainty. It appears unlikely that l-lysine prevented the analgesics from getting to active sites since plasma or brain levels of flunixin were not altered for up to 2 hr after drug administration and binding of flunixin to plasma protein was not affected. Blockade by l-lysine appears to occur at least in part at a peripheral site since it was not blockade by l-arginine or l-ornithine which compete for a common transport system with l-lysine and, hence, would have reduced the effect of l-lysine if its actions were central. However, blockade within the central nervous system cannot be ruled out. Antagonism by l-lysine does not seem to involve endogenous serotonin since it was not reversed by the serotonin precursor, 5-hydroxytryptophan, or by fluoxetine, a specific blocker of serotonin uptake. In contrast to the block of non-narcotic analgesics, l-lysine potentiated the antinociceptive effects of morphine.

[Effect of thyrocalcitonin on the pain sensitivity in animals]. / Effect tirokal'tsitonina na bolevuiu chuvstvitel'nost' zhivotnykh.

With a single parenteral introduction of thyrocalcitonin (TCT) the algesthesia of soft tissues (tall skin, paw) is moderately increasing, while the algesic action of morphine and promedol against the background of TCT-gets weaker. And contrarywise algesthesia of hard tissues of the tooth becomes significantly lower under the effect of TCT and this continues for a long time.