Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Methacholine Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1981

Possible involvement of the cholinergic system in hormonal secretion by the perfused pancreas from ventromedial-hypothalamic lesioned rats.

Total arginine-induced secretion of insulin, glucagon and somatostatin was studied during a 20 min period in isolated perfused pancreases from control and non-hyperphagic ventromedial hypothalamic (VMH) lesioned rats. Compared to controls pancreases from VMH-lesioned rats secreted more insulin (82 +/- 13 ng vs 36 +/- 9 ng) and more glucagon (130 +/- 23 ng vs 73 +/- 14 ng) but less somatostatin (0.58 +/- 0.18 ng vs 1.12 +/- 0.14 ng). These abnormalities were restored to normal by perfusion with atropine (25 mumol/l). Pancreases of both groups were perfused with the cholinergic agonist methacholine (100 mumol/l). Again pancreases from VMH-lesioned rats secreted more insulin (157 +/- 19 ng vs 33 +/- 6 ng) and more glucagon (95 +/- 13 ng vs 57 +/- 9 ng) but less somatostatin (0.80 +/- 0.15 ng vs 1.30 +/- 0.18 ng). These results support the concept that, in pancreases isolated from VMH-lesioned rats increased "cholinergic activity" may prevail via increased release of endogenous acetylcholine from islet-postsynaptic ganglion cells together with increased numbers of muscarinic receptors on postsynaptic ganglion cells as well as on endocrine cells.

Animals↗
PubMed1978

Pupillary abnormalities in schizophrenic patients during long-term administration of psychotropic drugs: dissociation between light and near vision reactions.

Pupillographic studies were made of the reactions to light and near vision in 12 schizophrenic patients under long-term administration of psychotropic drugs. The results showed a significant reduction in the light reaction, while the near vision reaction was preserved. The pupillographic study revealed not only reduction in amplitude of the light reaction but also changes in dynamic aspects of the reaction, i.e., prolonged latency time, shortened constriction time, and half redilatation time after the light stimulus. The mechanisms underlying the dissociation between light reaction and near vision reaction induced by long-term administration of psychotropic drugs are obscure, but both the peripheral and central actions of these drugs may be involved.

Adult↗
PubMed1984

Scanning electron microscopy of nasal arterioles effected by vasoactive agents.

Morphological changes in nasal blood vessels induced by alpha- and beta-adrenergic and cholinergic agonists were studied under a scanning electron microscope after removal of extracellular connective tissue and the basal lamina. Arterioles were constricted and dilatated following topical application of alpha-adrenergic and cholinergic agonists. Distinctive morphological changes were observed on their smooth muscle cells. Smooth muscle cells of constricted arterioles had a rugged surface with numerous fine invaginations. However, in dilatated arterioles the cells had a smooth surface and intercellular spaces were clearly revealed. No remarkable changes were produced in smooth muscle cells by the beta-adrenergic agonist. It is concluded that nasal arterioles are sensitive to alpha-adrenergic and cholinergic stimulation but not to beta-adrenergic stimulation.

Animals↗
PubMed1984

Nasal responsiveness to methacholine stimulation in allergic rhinitis patients.

We examined the nasal responsiveness to topical methacholine application in allergic rhinitis and non-allergic chronic rhinitis patients, and in control subjects. Methacholine responsiveness was significantly higher in allergic rhinitis patients than in non-allergic patients and control subjects. In perennial rhinitis, methacholine responsiveness correlated with the severity of daily nasal symptoms and those provoked by specific allergen challenge tests. Among nasal symptoms, hyper-rhinorrhoea was found to be closely related to methacholine responsiveness. As a result of these findings, the possibility of cholinergic hyper-reactivity in allergic rhinitis patients is discussed.

Administration, Topical↗
PubMed1985

Substance P antagonists and mucociliary activity in rabbit.

Substance P (SP) is known to accelerate mucociliary (m.c.) activity in the rabbit maxillary sinus in vivo. The physiological significance of this finding was investigated by testing three putative SP antagonists. [Arg5, D-Trp7,9, Nle11]SP5-11 could not be used as an antagonist because it stimulated m.c. activity. [D-Arg1, D-Trp7,9, Leu11]SP had no effect on the m.c. activity changes induced by SP. [D-Pro2, D-Trp7,9]SP was found to be an effective antagonist, 1 mg/kg of this drug reversibly inhibiting both the effects of 0.1 micrograms/kg SP and the stimulating effect of 1.0 micrograms/kg bradykinin and 30.0 micrograms/kg capsaicin; the stimulating effect of 0.5 micrograms/kg methacholine was not inhibited. It is suggested that bradykinin and capsaicin stimulate m.c. activity at least partly by releasing SP. The results of this investigation also support the view that the accelerating effect of SP on m.c. activity reflects physiological SP-mediated protective mechanisms in the airways. It is concluded that [D-Pro2,D-Trp7,9]SP is a useful pharmacological tool for studying the role of SP in the control of m.c. activity in rabbits.

Animals↗
PubMed1984

Clonidine inhibits salivary secretion by activation of postsynaptic alpha 2-receptors.

The effects of clonidine on the submaxillary gland of the rat were studied. Doses ranging between 100 to 3.000 micrograms/kg produced a sustained secretory response which was blocked by 0.1 mg/kg of prazosin but not by 1 mg/kg of yohimbine. Clonidine 10 micrograms/kg markedly inhibited the salivation induced by noradrenaline, methacholine and substance P but not that induced by isoproterenol. The inhibition caused by the alpha 2-agonist was greater for noradrenaline than for either methacholine or substance P. Blockade of alpha 2 adrenoceptors with yohimbine (0.3 - 1 mg/kg) prevented the inhibition by clonidine of noradrenaline, methacholine and substance P induced salivation. On the other hand, prazosin 0.1 mg/kg did not modify the inhibition by clonidine of methacholine induced secretion. The results obtained indicate that clonidine exerts a dual effect on salivary secretion: at high doses it elicits salivation through activation of alpha 1-adrenoceptors; at the dose of 10 micrograms/kg clonidine activates alpha 2-adrenoceptors which inhibit the secretory response evoked through either muscarine, substance P and alpha 1-adrenoceptor agonists.

Animals↗
PubMed1981

The effects of several muscarinic antagonists on pre- and postsynaptic receptors in the isolated rabbit heart.

In order to reveal possible differences between pre- and postsynaptic muscarine receptors, seven antagonists were tested for their affinities on these receptor sites in the rabbit isolated perfused heart. Methacholine was used as an agonist to inhibit the noradrenaline overflow evoked by electrical stimulation (3 Hz, 3 min) of the sympathetic nerves (presynaptic parameter) and to decrease the systolic tension development of the right atrium (postsynaptic parameter). The affinity of an antagonist was expressed as pA2. A decreasing order of potency was obtained with ipratropium, scopolamine, atropine, trihexyphenidyl, amitriptyline, and gallamine, both for pre- and postsynaptic responses. The antagonists acted competitively and their effects were reversible. Furthermore, for none of the drugs did the pA2 (pre) differ from the pA2 (post). With QNB (3-quinuclidinyl benzilate) a pA2 (post) of 11.65 was obtained. However, the affinity to presynaptic receptors could not be determined as a pA2 value due to the very prolonged exposure time required for the equilibrium with QNB and for that with methacholine in the presence of QNB. It is concluded that the antagonists employed do not reveal differences between pre- and postsynaptic muscarine receptors of the rabbit heart, in spite of their greatly varying chemical structure and their individual affinities ranging over 5 orders of magnitude. The findings confirm the view of a homogeneous muscarine receptor population characterized by functional parameters.

Animals↗
PubMed1976

Effects of methacholine, histamine and atropine on pulmonary guanosine-3', 5'-monophosphate levels in hypersensitive mice.

Pulmonary levels of cGMP and cAMP in mice sensitized to methacholine and histamine with B. pertussis were examined to determine whether sensitization could be the result of an alteration in the metabolism of these cyclic nucleotides. The results presented show that in sensitized mice, methacholine raised cGMP to levels that were about double those produced without sensitization. In analogous experiments, histamine raised cGMP by approximately 100% in sensitized mice without producing significant increases in nonsensitized groups. Atropine completely blocked the cGMP rises produced by methacholine but did not eliminate those produced by histamine, thus indicating that cholinergic, but not the histaminergic elevation of cGMP involves activation of muscarinic receptors. The influence of pertussis on cAMP appeared to be opposite in direction from cGMP, i.e., a small but significant drop in cAMP levels was found following methacholine administration to sensitized, but not to nonsensitized mice. It was concluded that pertussis sensitization increases the responsiveness of the pulmonary guanylate cyclase-cGMP system to methacholine and histamine, and that the altered patterns of cGMP accumulation may contribute to the biochemical mechanism of sensitization.

Animals↗
PubMed1975

Muscarinic inhibition of potassium-induced noradrenaline release and its dependence on the calcium concentration.

1. Noradrenaline release from the isolated rabbit heart was evoked by perfusion with a medium containing 135 mM potassium and 17 mM sodium ions (high K+-low Na+). 2. The noradrenaline output in response to high K+-low Na+ was dose-dependently decreased by methacholine (0.625-320 muM) and this effect was reserved by atropine 1.44 mM. 3. Lowering the calcium concentration of high K+-low Na+ from 1.8-0.1125 mM decreased the noradrenaline output by 85%. The effect of methacholine, expressed as % inhibition of noradrenaline release, was potentiated by lowering of the calcium concentration. 4. Both at normal and lowered calcium concentrations the inhibitory action of methacholine was larger from 0-5 than from 5-10 min after perfusion with high K+-low Na+. 5. Perfusion of hearts with media containing high K+-low Na+ or normal K+-low Na+ caused noradrenaline outputs somewhat smaller than those after high K+-low Na+. The release from 0-5 min was both calcium-dependent and inhibited by methacholine. 6. High K+ and/or low Na+ solutions caused an increase in coronary perfusion pressure which was little affected by the noradrenaline released simultaneously. 7. It is concluded that activation of muscarine receptors at the terminal adrenergic fibre decreases the availability of calcium for transmitter release.

Animals↗
PubMed1984

Inhibitory effect of dopamine on canine gastric fundus.

The mechanism of the inhibitory effect of dopamine on canine stomach fundus was studied in longitudinal and circular muscle fundus strips, contracted by transmural electrical stimulation or by methacholine. Results obtained for longitudinal and circular strips were similar. Dopamine (1 X 10(-6)-1 X 10(-4) M) concentration-dependently inhibited frequency-response curves to electrical stimulation; these concentrations did not change the resting tone of the strips. Dopamine (1 X 10(-4) M), tested on contractions of similar amplitude induced in the same strips by electrical stimulation at 0.5 Hz and by methacholine, inhibited the electrically induced contractions but had little influence on the contractions induced by methacholine. The inhibition of the electrically induced contractions by dopamine 1 X 10(-4) M was not influenced by the presence of cocaine 3 X 10(-5) M or hydrocortisone 3 X 10(-5) M. The alpha 1- and alpha 2-adrenoceptor antagonist phentolamine and the alpha 2-adrenoceptor antagonist rauwolscine markedly antagonized the inhibitory effect of dopamine on the response to electrical stimulation at 0.5 Hz. The alpha 1-adrenoceptor antagonist prazosin and the dopamine receptor antagonists haloperidol and domperidone had no effect. The dopamine receptor antagonist metoclopramide decreased the inhibitory effect of dopamine but had a similar effect on the inhibition caused by noradrenaline. These results indicate that the inhibitory effect of dopamine in the dog gastric fundus is mainly mediated by an interaction with alpha 2-adrenoceptors on the intramural cholinergic neurons; this effect is largely direct since it was not influenced by cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1985

Protective effect by UCB JO28 against histamine and methacholine induced bronchial hyperreactivity.

UCB JO28 [( 2-[2-[4-(diphenylmethylene)-1-piperidinyl] ethoxy] ethoxy] acetic acid, hydrochloride) is derived from diphenylmethylene piperidine. Animal experiments have shown that it has spasmolytic properties for smooth muscle, particularly in the bronchi, as well as anti-Hl, anticholinergic and anti-serotonin activities. The degree of protection by JO28 against histamine and methacholine-induced bronchospasm has been investigated in 20 asthmatic patients with serious airways hyper-reactivity. Protection against histamine-induced bronchospasm was almost complete in 11 out of 12 patients, whereas protection against methacholine-induced bronchospasm, although clearly present in seven of eight patients, was less marked.

Adolescent↗
PubMed1988

Protective effect of tulobuterol on methacholine-induced bronchospasm in asthmatic children.

In a single-blind, placebo-controlled trial 19 asthmatic children aged 10-14 years were studied during a stable phase of the disease. All patients were tested with a methacholine inhalation test on two consecutive days, on the first day after oral administration of a placebo, and on the second day following an oral dose of tulobuterol HCl. The cumulative methacholine dose required to produce at least a 20% decrease in FEV1 was significantly higher after tulobuterol than after the placebo. It is concluded that tulobuterol HCl reduces methacholine-induced bronchospasm in children.

Adolescent↗
PubMed1989

Okadaic acid, a phosphatase inhibitor, produces a Ca2+ and calmodulin-independent contraction of smooth muscle.

The effects of okadaic acid, a phosphoprotein phosphatase inhibitor, on the contractile response and on myosin light chain phosphorylation were studied in intact lamb tracheal smooth muscle. The effects of okadaic acid were compared to the response of the same fibers stimulated with 1 microM methacholine, a concentration that induces 90% of maximal force. Okadaic acid (50 microM) produced a slow but maximal contraction that was accompanied by an increase in phosphorylation of the 20 kDa light chain of myosin. The myosin light chain phosphorylation pattern induced by okadaic acid, however, differed from that induced by methacholine. Ca2+ depletion, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a calmodulin antagonist and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), a protein kinase C inhibitor, blocked or attenuated methacholine-induced contractions but had no significant effect on force development or myosin light chain phosphorylation induced by okadaic acid. These results suggest that phosphorylation of the 20 kDa light chain of myosin is essential for smooth muscle contraction; they also suggest that okadaic acid either uncovers or activates an apparently Ca2+ and calmodulin-independent protein kinase activity that phosphorylates the 20 kDa light chain of myosin at multiple sites.

Animals↗