Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: DrugBank:EXPT02427 (Atropine)
 3,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many plants are recommended in traditional medicine as active against various effects of snakebite. Few attempts have been made to investigate the veracity of these assertions in controlled experiments. Several workers, mainly Oriental, have investigated the reputation of such plants by performing in vitro and in vivo experiments in order to demonstrate whether there was any protective effect, using drugs or mixtures of drugs prepared using traditional formulae. In some studies, these extracts were administered to mice before or after treatment with different elapid or crotalid venoms. Other papers deal with selected compounds isolated from Schumanniophyton magnificum, Eclipta prostrata or Aristolochia shimadai, and their capacity to inhibit phospholipase A2 or other enzymes (e.g. ATPase) or for physiological and biochemical properties (such as effects on uterine tone or the protection of mitochondrial membranes). Japanese workers have described the antihaemorrhagic effect of persimmon tannin from Diospyros kaki. Atropine has been attributed a life-prolonging effect after black mamba venom treatment. Prolonged survival was also observed after pretreatment with extracts of Diodia scandens and Andrographis paniculata. Some authors have found little or no beneficial effects. The papers collected so far show that there are no systematic investigations in this field.
 ...
PMID:Plants with a reputation against snakebite. 144 Jun 20

In guinea-pig ileal longitudinal smooth muscle, both palytoxin (PTX) and carbachol (CCh) increased K+ efflux with an EC50 of 1.8 X 10(-10) M and 4.1 X 10(-7) M, respectively. Atropine (10(-6) M) did not inhibit the K+ efflux due to PTX (3 X 10(-9) M), but completely inhibited the efflux due to CCh (10(-5) M). External Ca2+ removal and verapamil (10(-5) M) did not change the PTX-induced K+ efflux, although the CCh-induced K+ efflux was inhibited about 77% and 71%, respectively. PTX-induced K+ efflux was reduced to 31% by a depletion of intracellular Ca2+. Tetraethylammonium (15 mM) inhibited the K+ efflux due to PTX or CCh to 61% or 75%, respectively. The PTX-induced K+ efflux was also inhibited by cymarin (3 X 10(-8) M), ouabain (10(-5) M) and digitoxin (10(-5) M). These results suggest that the PTX-induced K+ efflux is less dependent on Ca2+ influx than that due to CCh. Furthermore, the binding sites for PTX in the ileal muscle of guinea-pig may be Na+, K+-ATPase, as has been suggested in other types of cells.
 ...
PMID:Palytoxin-induced K+ efflux from ileal longitudinal smooth muscle of the guinea-pig. 289 32

Preparations of lysed synaptosomes exhibit a high affinity Ca2+/Mg2+ ATPase and ATP-dependent Ca2+ accumulation activity, with a Km for Ca2+ congruent to 0.5 microM, close to the cytosolic concentration of Ca2+. When these membrane suspensions were incubated with cholinergic agonists muscarine or oxotremorine (1-20 microM), both Ca2+/Mg2+ ATPase and ATP-dependent CA2+ uptake were inhibited in a concentration-dependent fashion. Atropine alone (0.5-1.0 microM) had no effect on either enzyme or uptake activity, but significantly inhibited the actions of both muscarine and oxotremorine. No significant effects by cholinergic agonists or antagonists were seen on fast or slow phase voltage-dependent Ca2+ channels or Na+-Ca2+ exchange. These results suggest that activation of presynaptic muscarinic receptors produce inhibition of two processes required for the buffering of optimal free Ca2+ by the nerve terminal. Activation of presynaptic muscarinic receptors have been reported to reduce the release of ACh from nerve terminals. Alterations in intracellular free Ca2+ may contribute to a reduction in transmitter (ACh) release seen following activation of cholinergic receptors.
 ...
PMID:Activation of central muscarinic receptors inhibit Ca2+/Mg2+ ATPase and ATP-dependent Ca2+ transport in synaptic membranes. 315 60

The membrane-bound ATP-dependent energy systems (ATP-membrane ATPase-ADP and ATP-adenylate cyclase-cAMP) play an essential role in the physiological regulation of the gastrointestinal mucosa and its damage in rat and man. A good, physiologically, hormonally and pharmacologically well controlled and regulated feedback system exists between the two energy systems. The significant increase of ATP transformation into ADP or cAMP represents a causative metabolic background of the development of gastric, duodenal and jejunal ulcer (damage) in man and rat. The ulcer preventive effects of vitamin A, beta-carotene, atropine, cimetidine, prostacyclin I2, and surgical vagotomy were studied in connection with their effects on the membrane-bound ATP-dependent energy systems of the gastric, duodenal and jejunal mucosa in man and rat. Atropine and cimetidine were applied in cytoprotective and antisecretory doses, and the tissue levels of ATP, ADP, AMP, cAMP and lactate were measured. The results indicated that the disturbed equilibrium between the two energy supply systems can be modified (normalized) by drugs and surgical vagotomy; the drug effect depends on the actual biochemism of the gastroduodenal mucosa; the values of affinities (pD2) and intrinsic activities (alpha) of the different drugs differ in relation to membrane-bound ATP-splitting enzymes; the changes in the membrane-bound ATP-dependent energy systems of the damaged rat gastric mucosa, produced by vitamin A and beta-carotene, depend on their cytoprotective doses which are connected with their cytoprotective effects; the biochemical changes induced by drugs (given in cytoprotective and anti-secretory doses) differ only quantitatively but not qualitatively; the drug effects on the membrane-located ATP-splitting enzymes (membrane ATPase and adenylate cyclase) in human gastric, duodenal and jejunal mucosa are similar to those in rats, but their affinities (pD2) and also their intrinsic activities (alpha) differ to the enzyme systems.
 ...
PMID:Molecular biochemistry and pharmacology of peptic ulcer treatment. A review. 331 63

Gastric ulcerations induced in rats by a combination of indomethacin and cold-stress (5 +/- 1 degrees C) for 6 hr were more severe than those induced by indomethacin or cold-stress alone. The acidity of gastric juice was increased in rats treated with indomethacin plus cold-stressed. Histamine H2 receptor antagonists, (H+-K+) ATPase inhibitors and prostaglandins inhibited gastric ulcer formation in indomethacin plus cold-stress treated rats, whereas anticholinergics aggravated the ulceration. The indomethacin plus cold-stress induced acid secretion was inhibited by cimetidine and omeprazole in pylorus-ligated rats. Atropine had less effect on the increase in acidity than cimetidine and omeprazole. These findings indicate that the ulcer formation in indomethacin plus cold-stress treated rats is related the increased in acidity of gastric juice. This gastric ulcer model may be useful for evaluating antiulcer agents.
 ...
PMID:Effects of indomethacin and cold-stress on gastric acid secretion and ulceration. The effects of anti-acid secretory agents in rats. 367 83

Acetylcholine (ACH) produced specific inhibition of Na, K-ATP-ase activity in sarcolemmic preparations of the frog heart (K0.5 = 1 microM), dog atria (K0,5 = 5 microM) and ventricles (K0.5 = 1 microM), and dog small intestinal smooth muscles (K0,5 = 0.5 microM). K0.5 is the concentration causing a half-maximal effect. Atropine (10(-7) = 10(-6) M) blocked the inhibitory effect of ACH. The preparations contained a considerable number of 3H-quinuclidinyl benzilate (3H-QNB) binding sites. Treatment of atrial sarcolemma with a mixture of digitonin and sodium cholate resulted in a substantial decrease in the number of 3H-QNB binding sites in the membrane, while Na,K-ATPase lost responsiveness to ACH. In the presence of 10 microM GTP there was a noticeable decrease in sensitivity of the enzyme to ACH. It is assumed that inhibition of Na, K-ATPase activity by acetylcholine is mediated by muscarinic receptor activation with the involvement in this process of GTP-binding proteins.
 ...
PMID:[M-cholinoreceptor-mediated inhibition of Na, K-ATPase activity in the myocardial sarcolemma and intestinal smooth muscles by acetylcholine]. 609 7

Dose-dependent inhibition of Na+, K+-ATPase by acetylcholine was found in dog heart sarcolemma obtained after treatment with NaI. The enzyme was completely inhibited at 1 X 10(-2) M concentration of acetylcholine (Ki = 14 +/- 2 mM). Low concentrations of acetylcholine (1 X 10(-6)--1 X 10(-5) M) increased the Na+, K+-ATPase activity, the intermediate (5 X 10(-5)--5 X 10(-4) M) and high (1 X 10(-3)--1 X 10(-2) M) concentrations decreased the activity in the preparations enriched with sarcoplasmic vesicles. Sodium dodecylsulfate enhanced the activating effect but did not affect the inhibition. Atropine (1 X 10(-6)--1 X 10(-4) M) decreased the Na+, K+-ATPase activity and protected the enzyme against the inhibitory effect of acetylcholine. The data obtained suggest that interaction of acetylcholine with integral membrane proteins (Na+, K+-ATPase and/or muscarinic acetylcholine receptors) is apparently responsible for the neurotransmitter inhibitory effect.
 ...
PMID:[Effect of acetylcholine on the Na+,K+-ATPase activity of different preparations of myocardial sarcolemma]. 630 Nov 55

1. The effect of Na+,K(+)-ATPase inhibition by ouabain on gastric acid secretion was studied in the mouse isolated whole stomach preparation. 2. Ouabain caused a transient enhancement of histamine-induced gastric acid secretion followed by an inhibitory phase. On the other hand, ouabain caused a rapid reduction of bethanechol-stimulated acid secretion without an enhancement phase. 3. In dibutyryl cyclic AMP-induced acid secretion, ouabain led to a transient increase in acid secretion followed by a fall, as was seen with the histamine stimulation. Ouabain caused a rapid reduction of A23187-induced acid secretion. 4. Ouabain by itself increased basal acid secretion, and thereafter slowly suppressed the acid secretion. 5. Atropine inhibited both the ouabain-induced enhancement of the stimulated gastric acid secretion and the ouabain-induced stimulation of basal acid secretion. 6. The present study showed that Na+,K(+)-ATPase inhibition by ouabain caused a phasic enhancement of the stimulated gastric acid secretion through release of endogenous acetylcholine when the secretagogues act via an intracellular cyclic AMP pathway. It also inhibited the stimulated acid secretion irrespective of secretagogues, probably through its inhibitory effect on Na+,K(+)-ATPase in the gastric parietal cell.
 ...
PMID:Differential effects of Na+, K(+)-ATPase inhibition by ouabain on acid secretory responses to histamine and bethanechol in the mouse isolated stomach. 803 67

In spite of its effectiveness against microfilariae, very little is known about diethylcarbamazine's (DEC) therapeutic mechanism of action or the toxic sequelae which can result from overdose. In preliminary studies, a precipitous decrease in heart rate was noted in rats receiving 1000 mg DEC/kg ip. This effect was less pronounced at 750 mg/kg and was non-existent at 500 mg/kg. In the present study, attempts to attenuate DEC's cardiopulmonary insult by pretreating animals with cyproheptadine failed. Atropine pretreatment failed to block the negative chronotropic effects of DEC, but did restore respiratory function and reduce the lethality associated with the drug. Biochemical studies showed that ATP:ADP ratios in the hearts from rats given high dosages of DEC were elevated over those in controls (11:1 versus 5:1). Inosine levels decreased in cardiac tissues taken from DEC-treated rats. Subsequent enzyme studies revealed that DEC has a potent inhibitory effect on calcium-dependent ATPases from a variety of tissues. Taken together, our data indicate that the mode of acute DEC-lethality involves cardiopulmonary suppression. Furthermore, the cardiac depressant effect of DEC appears related to inhibition of calcium ATPases in cardiac myocytes. To our knowledge, this is the first report of ATPase sensitivity to DEC, a finding that has interesting toxicologic and pharmacologic ramifications.
 ...
PMID:Studies on the acute lethality of diethylcarbamazine in the rat. 843 41

1. Cytosolic calcium concentration ([Ca2+]i) by indo 1 microspectrofluorimetry in freshly isolated cells and isometric contraction of isolated rings were measured in response to muscarinic cholinoceptor stimulation in rat tracheal smooth muscle. 2. In isolated myocytes, acetylcholine (ACh, 0.03-1 microM) caused a rapid and graded increase in [Ca2+]i up to a net amplitude of 492 +/- 26 nM (n = 19) which gradually declined. The EC50 for ACh was 0.13 microM. This first [Ca2+]i peak was followed, when the ACh concentration increased, in approximately 50-60% of the cells, by successive peaks of decreased amplitude ([Ca2+]i oscillations) superimposed on the plateau phase. Whereas the percentage of cells exhibiting [Ca2+]i oscillations remained consistent, the frequency of these oscillations increased to up to 10 min-1 with an ACh concentration of 100 microM. 3. Removal of extracellular calcium (in the presence of EGTA, 0.4 mM) or addition of the voltage-dependent Ca(2+)-channel blocker verapamil (10 microM) did not alter the first [Ca2+]i peak, the plateau or the oscillations induced by ACh or carbachol. In contrast, the specific inhibitor of the sarcoplasmic Ca(2+)-ATPase, thapsigargin (1 microM), completely abolished the [Ca2+]i response. Thapsigargin (1 microM) also blocked the caffeine (5 mM)-induced transient rise in [Ca2+]i. 4. Atropine (a non-selective muscarinic cholinoceptor antagonist) and 4-diphenyl acetoxy N-methyl piperidine (4-DAMP, a selective M3 antagonist) inhibited the [Ca2+]i response to muscarinic cholinoceptor activation with an IC50 of 13 and 20 nM, respectively. Pirenzepine (a selective M1 antagonist) also totally inhibited the [Ca2+]i response to ACh but with a higher IC50 of 2 microM. Methoctramine (a selective M2 antagonist) up to a concentration of 10 microM caused only a 40% inhibition. The effect of muscarinic antagonists on cumulative concentration-response curves (CCRC) for carbachol was assessed at the following concentrations: atropine and 4-DAMP at 3, 10 and 30 nM; pirenzepine 0.3, 1 and 3 microM, and methoctramine at 1, 3 and 10 microM. For these concentrations, all of the antagonists produced a rightward shift of the CCRC for carbachol and pA2 values were 9.2, 8.8, 6.7 and 6.3, respectively. 5. In conclusion, the present study indicates that muscarinic stimulation of rat isolated tracheal smooth muscle cells induces [Ca2+]i oscillations. The occurrence of these oscillations depends on the graded amplitude of the first [Ca2+]i rise and their frequency may play a role in the amplitude of the mechanical activity in response to muscarinic cholinoceptor activation. Both the [Ca2+]i and the contractile responses are primarily dependent on activation of the M3 receptor subtype.
 ...
PMID:[Ca2+]i oscillations induced by muscarinic stimulation in airway smooth muscle cells: receptor subtypes and correlation with the mechanical activity. 910 5


1 2 Next >>