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At least 19 recordsLinked to original sources

Effect of bombesin, a natural tetradecapeptide, on myoelectrical and mechanical activity of isolated, ex vivo perfused, canine stomach.

Electrical and mechanical activity were recorded from the canine stomach, isolated and ex vivo perfused with homologous blood. The action of Bombesin, a natural tetradecapeptide, was compared with the action of pentagastrin, methacholine and electrical stimulation on the electrical and mechanical activity of this isolated preparation. All drugs used and vagal stimulation resulted in premature control potentials, uncoupling of the normal phase locked pattern of electrical control activity, appearance of response activity and appearance of mechanical reaction. These responses were blocked or decreased by atropine, tetrodotoxin and hexamethonium. It appears that the neural release of acetylcholine is implicated in the mechanism of action of Bombesin gastrointestinal motility.

Action Potentials

Effect of metoclopramide on myoelectrical and mechanical activity of the isolated canine stomach perfused extracorporeally.

Totally isolated whole canine stomachs perfused, ex vivo, with homologous blood of living supporting dogs were used for recording of myoelectrical mechanical activities. Drugs were administered directly into the arterial system of the isolated stomachs either as flash injections or as constant infusions. Flash injection of metoclopramide (Maxeran) led to the response activity (spiking) and associated mechanical response. Electrical control activity was also affected by Maxeran: the changes consisted of premature control activity and uncoupling. Similar reactions were observed after flash injections of methacholine, pentagastrin or electrical stimulation of the Latarjet nerve. These reactions were dose-dependent. Tetrodotoxin, atropine, hexamethonium and glucagon, when given as a constant infusion, did inhibit the action of Maxeran on myoelectrical and mechanical activities of the isolated stomach. Inhibition of the responses to Maxeran by atropine and tetrodotoxin implicates acetylcholine in the mediation of these responses. The ability of hexamethonium to diminish the response to Maxeran suggests that a locus of action may be at both pre- and post-ganglionic sites of the intramural plexus. Exact receptors of this action are not demonstrated by this study.

Animals

Mechanism of action of pentagastrin on the lower esophageal sphincter.

The effects of pentagastrin on lower esophageal sphincter (LES) pressure has been studied in trained, unanesthetized dogs. LES pressure was monitored by an infusion manometric technique. Increasing doses of pentagastrin up to 3 mug/kg given as an i.v. bolus resulted in increasing rises in LES pressure; larger doses resulted in a lesser effect of shorter duration. Increasing i.v. boluses of methacholine produced greater increases in LES pressure up to a maximum of 5 mug/kg; higher doses had similar effects. Atropine (50-100 mug/kg) slightly diminished the response of the LES to 2 or 6 mug/kg of pentagastrin. In large doses (500-2,000 mug/kg), atropine did not diminish the response to pentagastrin and prolonged the response of 6 mug/kg pentagastrin. Hexamethonium (2 mg/kg i.v.) depressed the peak response to 3 mug/kg pentagastrin slightly but the response to 6 mug/kg was increased and prolonged. Propranolol (2 mg/kg i.v.) significantly prolonged the effect of 6 mug/kg pentagastrin on the LES. We conclude that the stimulatory effect of pentagastrin is mainly due to a direct action on the LES. A lesser stimulatory effect is due to an action on preganglionic cholinergic neurons. Large doses of pentagastrin have both stimulatory and inhibitory effects. The inhibitory effect is mediated at least in part via preganglionic neurons acting through adrenergic receptors. Ganglionic transmission of the effect may be through muscarinic as well as nicotinic receptors.

Acetylcholine

Pharmacological assessment of 3-tert-butylsydnone.

The pharmacological effects of the mesoionic derivative, 3-tert-butylsydnone, were investigated. Administration to rats caused clonic convulsions. The CD50 of 3-tert-butylsydnone was 0.471 +/- 0.033 mmole/kg. Trimethadione, but not phenytoin sodium or proadifen hydrochloride, protected the rat from the effects of 3-tert-butylsydnone. After administration of this compound, pentobarbital sodium sleeping time was reduced in the rat, but blood pressure and ECG were unchanged in the dog. Pretreatment of the mouse with 3-tert-butylsydnone did not influence the LD50 of epinephrine hydrochloride. The action of methacholine chloride in the rat was not blocked, and the pupil of the rabbit eye was unaffected. Tests for analgesic and oxytocic activity were negative. Chronic administration of a small dose to the rat for 70 days had no effect on blood glucose, blood urea nitrogen, hemoglobin, or microhematocrit values.

Anesthesia

Pharmacological properties of n1-piperonyl-n4-3,7,11-trimethyl-2,6,10-dodecatrienyl-piperazine, a new non-anticholinergic gastric antisecretory agent.

The special and general pharmacology of N1-piperonyl-N4-3,7,11-trimethyl-2,6,10-dodecatrienylpiperazine (U-27) is reported. According to the results of the animal experiments the compound turned out to be a well tolerated gastric antisecretory drug devoid of anticholinergic activity. The compound was able to prevent hypersecretion induced by pylorus ligature in rat and guinea pig. Its duration of action was remarkable and no tolerance occurred after a repeated treatment. The compound displayed also an interesting activity on several experimental ulcers.

Animals

Preliminary data on antiserotonin effects of oxatomide, a novel anti-allergic compound.

Oxatomide or R 35443, 1-(3-[4-(diphenylmethyl)-1-piperazinyl]propyl)-1,3-dihydro--2H-benzimidazol-2-one, a compound with potent antihistaminic and anti-anaphylactic activities, shows specific antiserotonin effects on isolated caudal arteries of the rat. In vivo it is a powerful antagonist of bronchospasm induced by serotonin and by histamine; it has no anticholinergic effects and does not affect blood pressure in spontaneously hypertensive rats. These antiserotonin properties of oxatomide may contribute significantly to its anti-allergic activity.

Animals

Two cases of acute pandysautonomia.

Two men had acute nonprogressive pandysautonomia. Both of them showed orthostatic hypotension, fainting in upright position, pupillary disturbances, diminished sweating, anacidity, and impotence. Case 1 showed considerable but inadequate improvement within 31 months. Case 2 recovered completely after 11 months. Clinical and pharmacodynamic investigations suggested that the main lesion was located in postganglionic fibers in case 1 and in preganglionic fibers in case 2. The cause of this disorder is unknown, although both patients had undergone substantial weight loss.

Acetylcholine

Myotonic pupils in Charcot-Marie-Tooth disease. Successful relief of symptoms with 0.025% pilocarpine.

Twenty-seven members of a family with dominantly inherited Charcot-Marie-Tooth disease (CMTD) were examined. Fifteen members had CMTD and 13 of these had varying amounts of myotonic pupillary abnormalities similar in some ways to Adie tonic pupil syndrome. Those with graver neurologic disease showed greater pupillary abnormalities. Ten of the 15 patients had pupillary constriction with methacholine chloride (Mecholyl) and some of these had extensive iris atrophy. Several affected patients received symptomatic relief from 0.025% pilocarpine. Seven other patients with CMTD who were not related to our initial family were checked for myotonic pupils; two had findings similar to our initial family. Pupillary abnormalities in certain patients with CMTD appear secondary to a parasympathetic denervation of the iris sphincter and ciliary muscle, as shown by a positive methacholine test, and probably represent part of the autonomic nervous system dysfunction associated with the polyneuropathy in CMTD.

Adult

Fisher's syndrome: a pharmacological study of the pupils.

A pharmacological study was performed in the involved pupils to demonstrate the site of lesion in a patient with Fisher's syndrome who showed marked ptosis, complete external ophthalmoplegia, pupillary involvement with anisocoria, facial paresis, ataxia, areflexia, and albuminocytological dissociation in the cerebrospinal fluid. The instillation of 2.5% methacholine produced mild constriction of one pupil. This response was not detectable in the recovery stage. The instillation of 1.25% l-epinephrine produced marked bilateral dilation of the pupils, in both the early and recovery stages. Instillation of 5% tyramine produced pupillary dilation as in the normal pupil. The response to 5% cocaine, tested only in the recovery stage, was weak in one pupil. These results imply that the pupillary involvement was due to peripheral involvement of the sympathetic and parasympathetic nervous systems. The lesion in the sympathetic nervous system was preganglionic, but in the parasympathetic nervous system the precise localization could not be determined.

Aged

Pharmacological studies of the pupils in familial amyloid polyneuropathy.

Pharmacological studies of the pupils of 7 patients with familial amyloid polyneuropathy (FAP) were performed in order to demonstrate the site of the lesion. Supersensitivity to 1.25% epinephrine was observed frequently, but not to 2.5% methacholine. The lesions of the sympathetic nervous system, judging from the epinephrine and tyramine tests, were regarded as preganglionic in 2 patients and postganglionic in 4. Among 3 patients reexamined six months later, 1 had developed signs of sympathetic postganglionic disturbance and another showed a peripheral parasympathetic disturbance associated with progress of a sympathetic preganglionic disturbance. From these results it was suggested that in FAP, sympathetic abnormalities involve the pupils more often than parasympathetic disturbances, and pharmacological studies can detect the autonomic dysfunction before it becomes clinically apparent.

Adult