Wirkungsmechanismen von Acetylcholin und Succinylcholin auf die Muskelspindeln des Frosches

Henatsch, H. D.; Schulte, F. J.

doi:10.1007/bf00369772

Cited by 35 publications

(11 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…does not desensitize the chemosensory fibres to the effect induced by intrastream injections of 100 #gACh (Eyzaguirre & Koyano, 1965b (see Thesleff, 1955 a, b). It has marked excitatory properties on other receptors such as the motor-innervated muscle spindles (Granit, Skoglund & Thesleff, 1953;Henatsch & Schulte, 1958). However, this finding has not been confirmed in isolated frog's spindles where all elements, except for the sensory innervation, have been destroyed (Ottoson, 1961).…”

Section: Effects Of Cholinergic Blocking Agentsmentioning

confidence: 96%

Pharmacology of pH effects on carotid body chemoreceptors in vitro

Eyzaguirre¹,

Zapata²

1968

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. The carotid body and the carotid nerve were removed from anaesthetized cats and placed in a small Perspex channel through which Locke solution (at various pH values and usually equilibrated with 50 % 02 in N2) was allowed to flow. The glomus was immersed in the flowing solution while the nerve was lifted into oil covering the saline. Sensory discharges were recorded from the nerve and their frequency was used as an index of receptor activity. At times, a small segment of carotid artery, containing pressoreceptor endings, was removed together with the glomus. In this case, pressoreceptor discharges were recorded from the nerve.2. The amplitude of either chemo-or pressoreceptor discharges was not changed by strong acid solutions. Acid decreased the frequency of the baroreceptor discharges only when pH fell to less than 4-0. Solutions at low pH increased the chemosensory discharge, but acid depressed the increased chemoreceptor discharge elicited by KCI. These experiments indicated that H+ ions probably acted as membrane 'stabilizers' without depolarizing either the nerve fibres or endings.3. Acid solutions increased the action of acetylcholine chloride (AChCl)

show abstract

Section: Effects Of Cholinergic Blocking Agentsmentioning

confidence: 96%

Pharmacology of pH effects on carotid body chemoreceptors in vitro

Eyzaguirre¹,

Zapata²

1968

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…This might lead to a partial inactivation of the spike-generating mechanism. Henatsch & Schulte (1958) obtained some evidence that in large doses suxamethonium had such a dual mechanism of action on spindles.…”

Section: Discussionmentioning

confidence: 99%

A comparison of the spindles in two different muscles of the frog

Brown¹

1971

The Journal of Physiology

View full text Add to dashboard Cite

SUMMARY1. The responses of spindles in the iliofibularis muscle of frogs to stretch during either small motor nerve fibre stimulation or the application of suxamethonium were compared.2. All spindles which were excited by small motor nerve fibre stimulation were also excited by suxamethonium, and their responses to these two methods of excitation were very similar. The drug dose was usually 5-10 ,g/ml. but smaller and larger doses were effective. Large doses ( > 100 ,tg/ml.) could sometimes lead to a reversible partial block of the spindle response to stretch.3. Suxamethonium also caused a prolonged contraction in extrafusal slow muscle fibres. This contraction was not responsible for the effect on the spindle, because the time course of its action on the muscle tension and on the spindle afferent was different.4. It was concluded that suxamethonium stimulated prolonged contraction in the small intrafusal muscle fibres, which are known to be innervated by the small motor nerve fibres.5. Only about half ofthe spindles in the iliofibularis muscle were excited by suxamethonium.6. In the sartorius muscle which has no slow extrafusal muscle fibres, no spindles were found to be excited by suxamethonium in the way characteristic of that due to small intrafusal muscle fibre contraction.7. It is concluded that, in frog muscles which have no slow extrafusal fibres, the muscle spindles do not have small intrafusal muscle fibres of the kind found in the iliofibularis muscle.

show abstract

“…This block can be overcome by increasing the dose of the agonist, as would be expected on the assumption that tubocurarine and the choline esters are competitive antagonists [see the recent study of Jenkinson (101) using twitch muscle fibers]. The observation that the spindle excitatory action of SCh can be obtained after doses of tubocurarine which block extra fusal and intrafusal n-m transmission has been cited as evidence that SCh acts directly on the sensory ending (81). However, this is not decisive since competition between SCh and tubocurarine could take place at either the afferent ending or the post-synaptic muscle membrane and would not neces sarily involve a detectable change in n-m transmission.…”

mentioning

confidence: 86%

“…Spindles in isolated frog muscles are also activated by ACh and SCh (Table I); however, investigation of the site and mechanism of action in such preparations is severely compromised by the occurrence of marked tachy phylaxis (81,138). There is a concomitant tachyphylaxis to the n-m blocking action of ACh (138).…”

mentioning

confidence: 99%

Neuromuscular Pharmacology: Drugs and Muscle Spindles

Smith¹

1963

Annu. Rev. Pharmacol.

View full text Add to dashboard Cite

This review is limited to a consideration of the direct and indirect actions of drugs on muscle spindle function. A detailed description of the various sensory endings, their characteristic responses to stimuli, and the function of these receptors in reflexes is outside the scope of this review. These topics have been discussed in a recent symposium (8) and other reviews (34,47,64,76,95).The mammalian muscle spindles are of particular interest since they contain the afferent ending for one of the basic reflexes, the stretch reflex. In addition to a complicated afferent system of one or more stretch sensitive endings, they possess specialized intrafusal muscle fibers which function as regulators of the sensitivity of the afferent receptor endings. The assess ment of drug effects upon these intrafusal fibers has, by necessity, been limited to indirect methods. Stimulation of the small, high threshold myeli nated fusimotor4 nerves innervating the intrafusal muscle fibers results in an increase in the frequency of discharge of spindle afferent nerves as well as an increase in the sensitivity to stretch of the sensory ending with, however, no alteration in gross muscle tension.It has not been proven that intrafusal neuromuscular (n-m) transmission is cholinergic but all data obtained to date are consistent with this assump tion. The endplates contain cholinesterase (30,31,32,75,89), transmission is blocked by extrafusal anticholinergic blocking agents (table I), and anti cholinesterases facilitate transmission (90) and antagonize tubocurarine block (54,55,80).Agents acting directly on spindles.-Tubocurarine, its dimethyl ether, and gallamine have been reported to block intrafusal n-m transmission ( Table 1). The intrafusal fibers appear to be less sensitive than the extrafusal; however, the difference in sensitivity is not great and it is difficult to block all extrafusal fibers and leave intrafusal n-m transmission unaffected (54, 55). Succinylcholine (SCh) rather selectively blocks extrafusal n-m trans-1 The survey of the literature pertaining to this review was concluded May 1962. S Abbreviations used in this chapter include: ACh (acetylcholine); nom (nerve muscle, neuro-muscular); SCh (succinylcholine).

show abstract

Wirkungsmechanismen von Acetylcholin und Succinylcholin auf die Muskelspindeln des Frosches

Cited by 35 publications

References 16 publications

Pharmacology of pH effects on carotid body chemoreceptors in vitro

Pharmacology of pH effects on carotid body chemoreceptors in vitro

A comparison of the spindles in two different muscles of the frog

Neuromuscular Pharmacology: Drugs and Muscle Spindles

Contact Info

Product

Resources

About