The Anticholinesterase Activity of Some Antiadrenaline Agents

Boyd, Helen; Chang, Vicky; Rand, M. J.

doi:10.1111/j.1476-5381.1960.tb00275.x

Cited by 78 publications

(81 citation statements)

References 11 publications

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“…A similar phenomenon has also been seen in the vas deferens (Boyd, Chang & Rand, 1960;Bulbring, 1968;Ambache & Zar, 1971;Drew, 1977a). Bulbring (1968) demonstrated that phenoxybenzamine potentiates responses to both direct and indirect (neuronal) stimulation of the vas deferens and Drew (1977a) suggested that its postsynaptic potentiating action is unrelated to an action on a-adrenoceptors.…”

Section: Potentiation Ofthe Twitch By Adrenoceptor Antagonistsmentioning

confidence: 63%

Distribution and Types of Adrenoceptors in the Guinea‐pig Ileum: The Action of Α‐ and Β‐adrenoceptor Blocking Agents

Bauer¹

1982

British J Pharmacology

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Czechoslovakia1 Transmurally stimulated segmeQts of the guinea-pig ileum have been used to analyse the different adrenoceptors in the terminal (0 to 3 cm) and the proximal (> 50 cm from the ileocaecal valve) ileum.2 The prejunctional adrenoceptors (located on the final, cholinergic, motor nerve terminals) and postjunctional adrenoceptors (located on the smooth muscle membrane) have been characterized according to their sensitivity to a-and 0-agonists and antagonists. 3 Phentolamine, phenoxybenzamine and yohimbine, in concentrations of 0.1 AM, transiently enhanced (up to 10%) the twitch response. At higher concentrations all the a-and P-antagonists studied depressed the neurogenic twitches and relaxed the smooth muscle.4 The twitch-inhibitory effects of adrenoceptor agonists (noradrenaline, adrenaline and ephedrine) were not antagonized by phenoxybenzamine (0.1, 0.5 and 1 tM), carbidine (0.5, 1 and 5 piM) and propranolol (0.5, 1 and 5 pM); however, they were depressed by phentolamine (0.1, 0.5, 1.25 and 5 pM) and yohimbine (0.25, 0.5 and 5pM). 5 The smooth muscle contractions induced by noradrenaline and adrenaline in the terminal ileum and by phenylephrine in both the terminal and proximal ileum were antagonized by phenoxybenzamine, carbidine and phentolamine but were not influenced by yohimbine and propranolol. 6 The smooth muscle relaxations of the proximal ileum induced by noradrenaline, adrenaline and ephedrine were inhibited by yohimbine, phentolamine, carbidine and phenoxybenzamine, and the isoprenaline-induced relaxation was antagonized by propranolol. 7 All the agonists studied, except phenylephrine, elicited relaxations of the acetylcholine-induced sustained contraction of both proximal and terminal ileum. The relaxation induced by isoprenaline was antagonized by propranolol, and the effects of noradrenaline and ephedrine by yohimbine.8 It is concluded that in the guinea-pig ileum there are postsynaptic P-adrenoceptors and at least two types of a-adrenoceptors: al-excitatory postjunctional adrenoceptors activated by phenylephrine, noradrenaline and adrenaline and antagonized by phenoxybenzamine, carbidine and phentolamine; a2-inhibitory prejunctional adrenoceptors activated by ephedrine, noradrenaline and adrenaline and inhibited by yohimbine and phentolamine. The inhibitory postjunctional aadrenoceptors are more close to the a2-adrenoceptors, since they were stimulated predominantly by ephedrine and noradrenaline and inhibited by yohimbine. 9 It has been shown that all a-adrenoceptor subtypes are to be found at every distance (0 to 70 cm) from the ileocaecal valve and that they can be activated in the resting or in the acetylcholinecontracted states.

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Section: Potentiation Ofthe Twitch By Adrenoceptor Antagonistsmentioning

confidence: 63%

Distribution and Types of Adrenoceptors in the Guinea‐pig Ileum: The Action of Α‐ and Β‐adrenoceptor Blocking Agents

Bauer¹

1982

British J Pharmacology

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“…The fact that these two drugs, though weaker than LSD, possess the ability to inhibit the motor transmission in the vas deferens (Boyd, Chang & Rand, 1960;Birmingham & Wilson, 1963) has been generally attributed to their well known x-adrenoceptor blocking property. This misconception has been removed in the present experiments by the use of LSD, which exerts an inhibitory action similar to that of ergotamine and dihydroergotamine on the motor transmission in the vas, but does so without producing any block of ox-adrenoceptors in the muscle.…”

Section: Discussionmentioning

confidence: 99%

An inhibition of post‐ganglionic motor transmission in the mammalian vas deferens by D‐lysergic acid diethylamide

Ambache¹,

Dunk²,

Verney³

et al. 1973

The Journal of Physiology

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SUMMARY1. Under certain conditions D-lysergic acid diethylamide (LSD), 10-9-10 g/ml., exerted an immediate, prolonged and slowly reversible inhibitory effect upon the post-ganglionic motor transmission in desheathed guinea-pig vas deferens preparations.2. The most critical factor influencing this action of LSD appeared to be the train length. With short trains of less than 4 or 5 pulses the twitch inhibition produced by LSD was often total. With longer trains (5-20 pulses), the degree of inhibition declined with increase in train length.These results suggest the existence of two components in the motor response to post-ganglionic stimulation, distinguished by their susceptibility to LSD.3. The inhibition of the LSD-susceptible component was related to the dose of LSD in the range 10-9-10 g/ml., reaching a maximum at 0*5-1 x 10 g/ml. The response remnants elicited by trains of more than 5 pulses under these conditions could not be reduced further by a ten-to twenty-fold increase in LSD concentration to 10-5 g/ml. and were in fact slightly potentiated.4. The inhibition of post-ganglionic motor transmission by LSD was not explicable on the basis of an a-adrenoceptor blockade because it was not associated with any reduction in motor responses to noradrenaline.5. The use of propranolol excluded mediation of the LSD-inhibition by ,8-adrenoceptors.6. The LSD effect was not due to a non-specific smooth muscle depression because it was not associated with any reduction in motor responses to acetylcholine, ATP or bradykinin.7. The inhibitory effect of LSD on post-ganglionic transmission resembled that of noradrenaline in that it-was antagonized by phentolamine; N. AMBACHE AND OTHERS another a-adrenoceptor blocking agent, phenoxybenzamine, was less effective than phentolamine in this respect.8. The LSD-inhibition was obtained in preparations taken from reserpinized guinea-pigs.9. The inhibition of motor transmission in the vas deferens by LSD was confirmed in rats, Meriones shawii and rabbits.10. The inhibition of post-ganglionic transmission by LSD was unrelated to its ability to antagonize 5-hydroxytryptamine (5-HT), to which the longitudinal muscle of the guinea-pig vas deferens is insensitive. The more potent 5-HT antagonists, methysergide and BOL 148 were either virtually inactive or considerably weaker than LSD.

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“…In the vas deferens it is well established that the height of the contractile response to nerve stimulation is resistant to reduction by a-adrenoceptor antagonists (Boyd, Chang & Rand, 1960;Ambache & Zar, 1971) at concentrations which increase the nerveinduced output of NA (Stjarne, 1973;Vizi, Somogyi, Hadhazy & Knoll, 1973). In order to explain this it has been suggested that the effector response is adrenergic but resistant to post-junctional blockade (Swedin, 1971;Furness, 1974) or alternatively due to a separate set of 'non-adrenergic' nerves (Ambache © Macmillan Journals Ltd 1979& Zar, 1971.…”

Section: Introductionmentioning

confidence: 99%

The EFFECTS OF Α‐ADRENOCEPTOR AGONISTS AND ANTAGONISTS ON RESPONSES OF TRANSMURALLY STIMULATED PROSTATIC AND EPIDIDYMAL PORTIONS OF THE ISOLATED VAS DEFERENS OF THE RAT

Brown

McGrath

Summers

1979

British J Pharmacology

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1 The effects of a-adrenoceptor agonists and antagonists on contractile responses of transmurally stimulated prostatic and epididymal portions of the rat isolated vas deferens were examined. 2 Responses to single stimuli consisted of two phases, the first predominant in the prostatic and the second in the epididymal portion. The first phase was resistant to a-adrenoceptor antagonists but the second was reduced in a dose-related manner in the order of potency prazosin > azapetine > phentolamine > labetalol > yohimbine. 3 Both phases of the response to a single stimulus were reduced by clonidine but only the first could be reliably restored by yohimbine. 4 Trains of transmural stimuli produced biphasic. responses, an early rapid component predominant in the prostatic and a slower secondary component predominant in the epididymal portion. The effects of a-adrenoceptor antagonists on these responses were complex. Prazosin produced the most straightforward inhibition of responses with relative resistance of the early rapid component. Only yohimbine and phentolamine produced increases in responses which could be pre-junctional in origin. 5 The a-adrenoceptor agonists, oxymetazoline and clonidine, reduced while phenylephrine increased responses to trains of stimuli. 6 These results are discussed in relation to the nature of the innervation of rat vas deferens and the usefulness of the preparation in pharmacological tests for activity at a-adrenoceptors.

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The Anticholinesterase Activity of Some Antiadrenaline Agents

Cited by 78 publications

References 11 publications

Distribution and Types of Adrenoceptors in the Guinea‐pig Ileum: The Action of Α‐ and Β‐adrenoceptor Blocking Agents

Distribution and Types of Adrenoceptors in the Guinea‐pig Ileum: The Action of Α‐ and Β‐adrenoceptor Blocking Agents

An inhibition of post‐ganglionic motor transmission in the mammalian vas deferens by D‐lysergic acid diethylamide

The EFFECTS OF Α‐ADRENOCEPTOR AGONISTS AND ANTAGONISTS ON RESPONSES OF TRANSMURALLY STIMULATED PROSTATIC AND EPIDIDYMAL PORTIONS OF THE ISOLATED VAS DEFERENS OF THE RAT

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