Chick Oesophagus Research Articles

Excitatory P1-purinoceptors on pre- and post-ganglionic cholinergic nerve terminals in the chick oesophagus.

The mechanism of action of ATP and the purinoceptors involved have been investigated on the chick oesophagus. The susceptibility of the excitatory responses to ATP/adenosine to tetrodotoxin indicates that their action is neurally mediated. Blockade of ATP/adenosine responses by atropine suggests the involvement of endogenous acetylcholine. ATP action depends on breakdown to AMP/adenosine, since theophylline blocks ATP/adenosine responses. The inhibition of ATP responses by pentolinium implies the involvement of preganglionic fibres.

The effects of diethylcarbamazine citrate on smooth muscle.

The effect of the anthelmintic drug diethylcarbamazine citrate (DECC) was examined on the guinea-pig isolated ileum, rabbit duodenum, chick oesophagus, rat portal vein and pig coronary artery. DECC contracted all the gastrointestinal smooth muscle preparations. The contractions were antagonized by hexamethonium and atropine but they were not affected by mepyramine or methysergide in concentrations that abolished, or markedly reduced, responses to histamine and 5-hydroxytryptamine. DECC inhibited the responses of the guinea-pig ileum to other spasmogens, namely, acetylcholine, histamine and nicotine. Physostigmine markedly potentiated the responses of the chick oesophagus and the rabbit duodenum to DECC. DECC relaxed the potassium chloride-induced contractions of the pig coronary artery strips; these relaxations were not modified by propranolol or calcium chloride. There was no evidence that DECC released histamine from skin or muscle.

AN ISOLATED PARASYMPATHETICALLY-INNERVATED OESOPHAGUS PREPARATION FROM THE CHICK.

Abstract An isolated parasympathetically-innervated preparation from the chick oesophagus is described. This preparation is essentially similar to mammalian parasympathetically-innervated smooth muscles in its responses to drugs, and because of its simplicity, robustness and cheapness it is recommended for use in student practical classes.

Possible involvement of a cholinergic mechanism in calcium-induced contractions of chick oesophagus.

Possible involvement of a cholinergic mechanism in calcium-induced contractions of chick oesophagus.

L‐arginine‐nitric oxide pathway involvement in the nerve‐evoked relaxant responses of the 5‐HT precontracted chick isolated upper oesophagus

1. The effects of tetrodotoxin (TTx) and the selective nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) on relaxant responses of the 5-HT precontracted chick isolated upper oesophagus to electrical field stimulation (EFS: 25-30V, 5 Hz for 10 s, 1 ms pulse width every 100 s) were investigated; the oesophagus was mounted under 1 g tension in Krebs solution containing 1 microM atropine. Appropriate tissue sections (30 microM thickness) of the chick oesophagus were also processed for NADPH-diaphorase histochemistry. 2. TTx (2 microM) and L-NAME (100-200 microM) inhibited the relaxant responses of the 5-HT precontracted chick oesophagus to EFS in a concentration-dependent manner; L-arginine (0.5-1 mM), but not D-arginine (0.5-1 mM), reversed the inhibition by L-NAME. In the absence of atropine and muscle tone, EFS produced contractile responses of the chick oesophagus that were completely abolished by 1 microM atropine, which also blocked the contractile response to acetylcholine (50 microM). 3. Under light microscopy, NADPH-diaphorase histochemistry confirmed the presence of nitric oxide synthase (NOS)-containing neurones and nerve fibres in the chick oesophagus. 4. The relaxant responses of the 5-HT precontracted chick isolated upper oesophagus to EFS are, therefore, mediated via the stimulation of non-adrenergic non-cholinergic nerves. These are likely to correspond to the histochemically identified NOS-containing neurones involved, presumably, in the synthesis and release of nitric oxide as the relaxant (inhibitory) neurotransmitter in this avian smooth muscle.

Developmental changes in morphine and clonidine sensitivity of isolated chick oesophagus

1. 1. Electrically evoked contractions of isolated newly-hatched and over 6 week-old chicks cervical oesophagus (pre-crop) were inhibited by morphine and clonidine in a dose-dependent manner. 2. 2. The inhibitory effects of morphine and clonidine were antagonized by naloxone (3 × 10 −6 M) and yohimbine (10 −7 M), respectively. 3. 3. IC 50 for morphine was 1.01 × 10 −7 M for newly-hatched and 5.19 × 10 −6 M for adult chicks. 4. 4. IC 50 for clonidine was 2.34 × 10 −9 M for newly-hatched and 1.19 × 10 −8 M for adult chicks. 5. 5. These findings indicate a significant decrease in inhibitory effect of morphine and clonidine during developmental stages.

Changes in morphine and clonidine sensitivity of isolated chick oesophagus during development

Changes in morphine and clonidine sensitivity of isolated chick oesophagus during development

Developmental disappearance of excitatory α1 adrenoceptor function in the oesophagus of chick embryo

1. Developmental change in the response to noradrenaline (NA) and 5-hydroxytryptamine (5-HT) was investigated in the chick oesophagus between 9 and 21 days of incubation and 4 days after hatching. 2. NA (5 microM) produced a significant contraction in the oesophagus at 9 days of incubation. The NA-induced contraction progressively decreased with development and changed to an inhibition of spontaneous contraction or a small relaxation by 17 days of incubation. 3. The NA-induced contractile response was inhibited by phentolamine (2.7 microM) and prazosin (0.55 microM). Phenylephrine (5 microM) but not clonidine (5-50 microM), also induced a contraction at early stages. The relaxation response to NA was sensitive to the beta-receptor blocker, carteolol (3.4 microM). 4. Pretreatment with carteolol unmasked the contractile responses to NA in preparations at 17-19 days of incubation. However, even in the presence of carteolol, the contraction produced by NA decreased and disappeared by the time of hatching. This change in response to NA is accompanied by a decline in the pD2 value. The response to phenylephrine (5 microM) followed the same pattern as that to NA. 5. The maximum binding sites of [3H]-dihydroergocryptine to the crude membrane preparation from oesophagus changed little at 13, 17 and 21 days of incubation. 6. Isoprenaline (Iso, 0.01-20 microM) caused a carteolol-sensitive relaxation in the carbachol-contracted oesophagus after 13 days of incubation. The sensitivity (pD2 value) to Iso decreased slightly up to 17 days of incubation. 7. 5-HT (10 microM) caused a contraction in the oesophagus after 13 days of incubation and the amplitudem of the response increased up to 17 days of incubation. The response to 5-HT was abolished by methysergide (1 microM) but not by tetrodotoxin (0.78 microM) or atropine (1 microM) at every stage tested. 8. These results suggest that the response to NA changed from an alpha-adrenoceptor-mediated contraction to a beta-receptor-mediated relaxation during the embryonic period, resulting partly from the decline and disappearance of excitatory alpha-receptor function in the chick oesophagus.

Development of cholinergic nerve transmission in the chick oesophagus

1. The onset and development of cholinergic mechanisms in the smooth muscle of the chick oesophagus were studied by estimating the changes in mechanical response and biochemical parameters between 9 days of incubation and 7 days after hatching. 2. Transmural and vagal nerve stimulation first evoked contraction in the oesophagus at 10 days and 11 days of incubation, respectively. These contractions were inhibited by atropine (1-2 microM) and potentiated by physostigmine (0.2 microM). On the other hand, hexamethonium (200 microM) had an inhibitory effect on vagal nerve stimulation but not on transmural nerve stimulation. 3. The relative amplitude of contraction induced by both vagal nerve and transmural stimulations compared to high K+ (80 mM)-induced contractions, progressively increased with age in embryos up to 19 days of incubation. 4. The activity of choline acetyltransferase (ChAT), an enzyme synthesizing acetylcholine (ACh), also gradually increased in the oesophagus during the period from 9 days to 19 days of incubation, which was similar to the change in the nerve-mediated contraction. On the other hand, the cholinesterase activity reached a maximum at 13 days of incubation and decreased until 7 days after hatching. 5. The contractile response to ACh and binding sites of [3H]-quinuclidinyl benzilate ([3H]-QNB) were observed in the oesophagus at 9 days of incubation. The maximum response produced by ACh (300 microM) tended to be greater in early stages (9-13 days of incubation) than in later stages. The sensitivity estimated from pD2 values increased up to 15 days of incubation. The maximum response produced by ACh (300 microM) tended to be greater in early stages (9-13 days of incubation) than in later stages. The sensitivity estimated from pD2 values increased up to 15 days of incubation. During the embryonic period, the number of muscarinic receptors estimated from the binding of [3H]-QNB changed very little. 6. These results suggest that in the chick oesophagus, extrinsic and intrinsic cholinergic innervation start to function at 10 days and 11 days of incubation, respectively and continue to develop progressively up to the time of hatching. It seems likely that the functional and biochemical maturation of receptive mechanisms on the smooth muscle precede those of cholinergic innervation.

Histamine-induced potentiation of cholinergic transmission in chick oesophagus ( Gallus gallus)

1. The effects of histamine on cholinergic nerve transmission were investigated in the oesophagus of the chick (0–29 days old). 2. Histamine potentiated the contractile responses produced by vagal or transmural nerve stimulation and by the ganglionic stimulant (DMPP) with the increase of tonus of oesophagus. On the other hand, a selective H 2 agonist, 4-methylhistamine, did not have any effect. 3. The sensitivity of oesophagus to ACh did not change in the presence of histamine (0.22–2 μM). 4. Mepyramine but not metiamide antagonized the contractile and potentiating effects of histamine. 5. From these findings, it is concluded that histamine preferentially acts on h 1-receptors located in cholinergic neurones to facilitate cholinergic transmission in the chick oesophagus, potentiating the nerve-mediated contraction.

Compound 48/80 elicits cholinergic contraction through histamine release in the chick oesophagus

1. 1. The effects of compound 48/80 on cholinergic nerve transmission and on the liberation of histamine in the isolated chick oesophagus were investigated. 2. 2. Compound 48/80 (0.2–1 μg ml −1) potentiated the cholinergic nerve-induced contraction and caused the contraction of the oesophagus itself. The latter response was prevented by atropine, tetraodotoxin and mepyramine but not by metiamide. 3. 3. Compound 48/80 released dose-dependently endogenous histamine from the isolated chick oesophagus. 4. 4. These results suggest that the action of compound 48/80 is mediated by the release of histamine from an endogenous pool and that histamine released endogenously facilitates the release of ACh from the intrinsic cholinergic nerve in the chick oesophagus.

Histamine response in developing chick oesophagus

Developmental changes in response to histamine were investigated in the oesophagus isolated from the chick between 15 days of incubation and 15 days after hatching. The contraction could be already caused by histamine (20 microM) in the chick oesophagus from 15 days of incubation. The pD2 values for histamine and acetylcholine did not change during the period between 17 days of incubation and 5 days after hatching. The response to histamine (20 microM) was extremely resistant to tetrodotoxin (0.78 microM), procaine (0.2 mM) and atropine (1 microM) during the period between 17 days of incubation and 20 days of incubation. The tetrodotoxin-resistant response was replaced by a tetrodotoxin-sensitive response after hatching. On the other hand, the neuronal response induced by transmural electrical stimulation (20 Hz) or dimethylphenylpiperazinium (20 microM) was uniformly sensitive to tetrodotoxin throughout the periods. Mepyramine (2 microM), but not metiamide (20 microM), inhibited the histamine-induced responses in every age tested. These results suggest that the myogenic receptivity of histamine transiently increases during the terminal period of embryonic development and declines after hatching.

The effects of protease inhibitor homologues from mamba snake venoms on autonomic neurotransmission

A. J. Anderson. The effects of protease inhibitor homologues from mamba snake venoms on autonomic neurotransmission. Toxicon 23, 947–954. 1985. — Five protease inhibitor homologues isolated from mamba venoms were tested for facilitatory actions on autonomic neurotransmission using isolated smooth muscle preparations. Dendrotoxin from the eastern green mamba ( Dendroaspis angusticeps) was the most consistent in augmenting the responses to sympathetic stimulation in vas deferens preparations and to parasympathetic stimulation in chick oesophagus preparations. Toxin 1 from the black mamba ( D. polylepis) venom augmented the neurally evoked responses in vas deferens preparations, and toxin K from the same venom augmented neurally evoked responses in chick oesophagus preparations. Proteins B and E from D. polylepis venom, as well as bovine pancreas trypsin inhibitor, had no significant facilitatory action on either smooth muscle preparation. The mechanism of the augmentation of neurally evoked responses produced by toxin 1 on vas deferens preparations, and dendrotoxin on chick oesophagus preparations, was investigated using a variety of drugs which interfere with cholinergic and adrenergic transmission. It is concluded that dendrotoxin and toxin 1 increase evoked transmitter release in the autonomie nervous system by a direct action on nerves.

P-210) - Developmental changes in activities of cholinergic enzymes and muscarinic receptors in the chick oesophagus

P-210) - Developmental changes in activities of cholinergic enzymes and muscarinic receptors in the chick oesophagus

Effects of Scopoletin on Autonomic Transmissions

AbstractThe effects of scopoletin, a coumarin isolated from the fruit of Tetrapleura tetraptera Taub (Mimosaceae), have been investigated on the electrically-induced contractions, relaxations and twitches of some cholinergically- and adrenergically-innervated muscle preparations in vitro and in vivo. Scopoletin depressed or abolished electrically-evoked contractions of the chick oesophagus, rabbit duodenum and guinea-pig vas deferens in vitro. The coumarin also reduced or abolished the indirect electrically-evoked twitches of the rat isolated hemidiaphragm muscle preparation, or the contractions of the cat nictitating membrane induced by pre-ganglionic cervical sympathetic nerve electrical stimulation in vivo. Furthermore, scopoletin prevented or reversed the high frequency electrical stimulation-evoked relaxations of the rabbit isolated duodenum. These results were taken to imply blockade of neurotransmitters by scopoletin at the cholinergic and adrenergic neuro-effector junctions, neuromuscular junction...

Developmental change in catecholamine receptors in the smooth muscle of chick oesophagus

Previously, we have reported that during embryonic development, noradrenaline (Nor)-induced response in the chick oesophagus changes from α -contraction to β-relaxation. In the present study, we further investigated the change of Nor response in relation to specific binding of [3H]-dihydroergocryptine (DHE) to crude membrane fraction of oesophagus. Contractile response to Nor (5μM) was already observed at day 8 of incubation and then changed to relaxation by day 17. However, in the presence of β-blocker (OPC-1085, 3μM), Nor could cause contraction at day 17. Phenylephrine (5μM) also induced contraction at this stage. Even in the presence of βblocker, the maximum contraction to Nor (relative contraction to 80mM K) progressively decreased from day 13 (104%) to day 21 (5%) with decline of pD2 values. On the other hand, the maximum binding sites of [3H]-DHE (fmol/ mg protein) were 136+12, 152±17 and 99 at day 13, 17 and 21, respectively. Remarkable decrease of maximum binding sites was not obtained between day 13 and day 21. The Kd values at day 13, 17 and 21 were 9.6±2.5, 9.0±2.0 and 14.4, respectively. These results suggest that developmental decrease of α-receptor -mediated contraction occurs during embryonic stages, but the decrease of contraction cannot be fully explained by the quantitative change in [3H]-DHE binding sites.

A study of histamine tachyphylaxis on isolated chick oesophagus

Summary Repeated administration of histamine to isolated chick oesophagus led to development of tachyphylaxis. The tissue did not develop tachyphylaxis to repeated administration of acetylcholine (ACh) or 5-hydroxytryptamine (5-HT). Histamine tachyphylaxis did not develop in the chick ileum. Physostigmine reversed histamine tachyphylaxis and potentiated histamine effect of the oesophagus. Although physostigmine alone induced oesophageal contractions the effect of physostigmine was independent of the physostigmine-histamine interaction. Atropine, hemicholinium-3 and morphine reduced the contractile responses of the oesophagus to histamine and they also retarded the rate of development of histamine tachyphylaxis. Mepyramine but not metiamide blocked histamine effects. It was concluded that histamine exerted both direct and indirect effects on the oesophagus. The interaction between physostigmine and histamine on the oesophagus probably involved an enhancement of cholinergic mechanisms as well as a nonspecific sensitization of the oesophagus by physostigmine.

Blockade of adrenergic and cholinergic transmissions by tetramethylpyrazine.

The pharmacological actions of an amide alkaloid, tetramethylpyrazine (TMPZ), isolated from the stem of Jatropha podagrica HOOK (Euphorbiaceae) have been investigated on the electrically-evoked contractions, relaxations and twitches of some cholinergically- and adrenergically-innervated muscle preparations in vitro and in vivo. The amide alkaloid depressed or abolished the electrically-evoked contractions of the chick oesophagus, rabbit duodenum and guinea-pig vas deferens in vitro. Tetramethylpyrazine also inhibited or abolished the indirect electrically-induced twitches of the rat isolated hemidiaphragm, or the contractions of the cat nictitating membrane evoked by pre-ganglionic cervial sympathetic nerve electrical stimulation in vivo. Moreover, TMPZ prevented or reversed the high frequency electrical stimulation-induced relaxations of the rabbit isolated duodenum. These results were taken to imply blocking actions of the amide alkaloid at the cholinergic and adrenergic neuro-effector junctions, the neuro-muscular junction, and at the ganglia (presumably indicating blockade of peripheral cholinergic and adrenergic transmissions).

Myogenic peristalsis in isolated preparations of chicken oesophagus.

1. Nicotine, 20 mug/ml, briefly and partially blocked the longitudinal contractions of a chick vagus nerve-oesophagus preparation to nerve stimulation, but potentiated them in the presence of hyoscine, 10 mug/ml.2. Strychnine, 20 mug/ml, antagonized the longitudinal contractions of the chick oesophagus to nerve stimulation, though not to acetylcholine or 5-hydroxytryptamine. Hyoscine, 10 mug/ml, enhanced the nerve-blocking action of strychnine.3. These observations suggest that in the vagus nerve of the chicken, hyoscine either blocks certain types of fibre selectively or interacts with pharmacological receptors for strychnine and nicotine.4. Tetrodotoxin, 1 mug/ml, propranolol, 40 mug/ml, cocaine, 200 mug/ml, or strychnine, 100 mug/ml, which render autonomic nerves inexcitable, potentiated the spontaneous movements of isolated preparations of chicken oesophagus at normal intra-luminal pressure; they also potentiated peristaltic response to increased intra-luminal pressure.5. These observations suggest that the preparations contain intramural nerves that inhibit the musculature.6. Peristalsis in the chicken oesophagus was unaffected by nicotine, 20 mug/ml, tubocurarine, 20 mug/ml, hyoscine, 10 mug/ml, phentolamine, 1 mug/ml, propranolol, 0.5 mug/ml, mepyramine, 1 mug/ml, methysergide, 0.1 mug/ml, and morphine, 20 mug/ml. It was produced in preparations of chicken oesophagus after removal of the mucous membrane. Papaverine, 20 mug/ml, inhibited the peristalsis and had a spasmolytic action in the musculature.7. These observations suggest that the peristalsis in isolated preparations of chicken oesophagus is dependent solely upon myogenic contractility.

A hyoscine-resistant contraction of isolated chicken oesophagus in response to stimulation of parasymphathetic nerves.

1. Contractions of the chicken isolated oesophagus or separated external muscle produced by stimulation of the vagus and descending oesophageal nerves were abolished by hyoscine (1-100 mug/ml.) if the duration of stimulation was less than 5 sec, but prolonged stimulation produced delayed contractions not antagonized by hyoscine.2. The contractions to nerve stimulation were abolished by nerve section but not by bretylium, hexamethonium or tubocurarine.3. In decerebrate chickens, intravenous hyoscine abolished the contractions of the oesophagus produced by nerve stimulation, but previous intravenous injection of hyoscine into chicks did not prevent subsequently isolated oesophageal preparations from contracting to nerve stimulation.4. Prolonged nerve stimulation of an isolated oesophageal preparation did not produce a contraction from a piece of isolated guinea-pig ileum or post-crop chick oesophagus suspended in the same organ-bath.5. It seems possible that small amounts of a slow contracting substance were released from the stimulated nerves together with acetylcholine.