5-Hydroxytryptamine in the phrenic nerve diaphragm: Evidence for its existence and release

Das, Mitali; Mohanakumar, Kochupurackal P.; Chauhan, S.P.S.; Ganguly, Dilip

doi:10.1016/0304-3940(89)90622-8

Cited by 4 publications

(4 citation statements)

References 24 publications

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“…This study will form the basis of further investigations aimed at identifying the presence of 5HT receptors at the neuromuscular junction of the rat phrenic nerve diaphragm preparation. This preparation was chosen because 5HT had been shown to be released from the phrenic nerve [9] implicating the transmitter in physiological function. We believe that this will enhance our understanding of neuromuscular physiology and establish a rationale for identifying 5HT receptors at the site by the use of 5HT agonists and antagonists.…”

Section: Introductionmentioning

confidence: 99%

“…The frequency selected for tetanic stimulation was standardized at 50 Hz because preliminary experiments suggested that this was the optimal mode of stimulation for demonstrating the effects of 5HT [9] in this preparation. 5HT was added to one hemidiaphragm in order to achieve the following final tissue bath concentrations (0.5, 1, 2, 4, 8, and 16 μmol L−1) while an equivalent volume of control solution (Krebs) was added to the contralateral hemidiaphragm which acted as a time‐matched concurrent control.…”

Section: Introductionmentioning

confidence: 99%

“…While 5HT and 5HT drugs have numerous effects on physiological systems, the neuromuscular junction has not been previously considered to be a site associated with significant 5HT activity. However, the release of 5HT into the junctional cleft of the neuromuscular junction [9] has led to speculation that it may have some hitherto undiscovered physiological role. In addition, the presence of 5HT at this site could mean that there are 5HT receptors located within the vicinity of the neuromuscular junction and these receptors may be the potential target sites for 5HT and 5HT drugs with clinically significant effects.…”

Section: Introductionmentioning

confidence: 99%

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5-Hydroxytryptamine potentiates post-tetanic twitch responses in the rat phrenic nerve diaphragm preparation

Hindle

Hopkins

1998

Eur J Anaesthesiol

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5-Hydroxytryptamine has wide-ranging effects on a number of physiological systems. In addition the exogenous application of 5-hydroxytryptamine or 5-hydroxytryptamine type drugs to tissue bath preparations has revealed the presence of a large and ever growing population of 5-hydroxytryptamine receptors. The discovery that 5-hydroxytryptamine is released at the neuromuscular junction raises the question as to whether it has a physiological function and whether or not applying low concentrations of 5-hydroxytryptamine transmitter would have any significant effect on twitch response at different rates of stimulation. Previous studies have demonstrated both facilitatory and depressant effects upon twitch responses in a variety of animal models. Single twitch responses of the rat phrenic nerve diaphragm preparation at non-fatiguing (0.3 Hz) and tetanic rates of stimulation (50 Hz) were recorded under conditions of indirect (nerve) stimulation at 4 g resting tension. The preparation was incubated with 0.5, 1, 2, 4, 16 mumol litre-1 concentrations of 5-hydroxytryptamine. The results of our investigations demonstrate that while low concentrations of 5-hydroxytryptamine have no effect upon the single twitch response at resting rates of stimulation (0.3 Hz), the initial single twitch and the subsequent eighteen responses immediately following a tetanus are facilitated (P < 0.05). This work demonstrates that 5-hydroxytryptamine does have significant effects upon the neuromuscular junction under conditions of physiological compromise (following tetanus). These observations are the first step, therefore, in a series of studies aimed at identifying the resident 5-hydroxytryptamine receptors within the neuromuscular junction which will subsequently enable us to predict therapeutic effect or toxicity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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5-Hydroxytryptamine potentiates post-tetanic twitch responses in the rat phrenic nerve diaphragm preparation

Hindle

Hopkins

1998

Eur J Anaesthesiol

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“…5-Hydroxytryptamine (5-HT) is released from the nerves innervating skeletal muscle preparations 1 where it may modulate the action of acetylcholine. High concentrations of 5-HT (millimolar) exhibit depressant effects on single twitch responses of skeletal muscle preparations.…”

mentioning

confidence: 99%

5-Hydroxytryptamine causes depression of twitch height in the partially curarized rat phrenic nerve hemidiaphragm preparation

Hindle

Hopkins

1998

British Journal of Anaesthesia

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5-Hydroxytryptamine (5-HT) has significant effects on the skeletal neuromuscular junction. We have evaluated the potential neuromodulatory effects of 5-HT on the rat hemidiaphragm using a non-fatiguing pattern of stimulation (0.3 Hz) in a partially curarized preparation using tubocurarine (EC50 = 560 (range 400-650) nmol litre-1). 5-HT was added to the partially curarized preparation in the following concentrations: 0, 12.5, 25, 50, 100, 200 and 400 nmol litre-1 and the twitch response was recorded at each concentration. These measurements were expressed as a ratio of control values, plotted against time and the area under the curve (AUC) calculated. The AUC values for test and control hemidiaphragms were compared by paired t test analysis accepting a 5% significance level. The mean AUC for test (3327 mm2) and control (4102 mm2) preparations were significantly different (P = 0.003). We have shown that the addition of low concentrations of 5-HT to the indirectly stimulated partially curarized rat diaphragm preparation caused depression of twitch height.

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Safety factor at the neuromuscular junction

Wood

Slater

2001

Progress in Neurobiology

375

289

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5-Hydroxytryptamine in the phrenic nerve diaphragm: Evidence for its existence and release

Cited by 4 publications

References 24 publications

5-Hydroxytryptamine potentiates post-tetanic twitch responses in the rat phrenic nerve diaphragm preparation

5-Hydroxytryptamine potentiates post-tetanic twitch responses in the rat phrenic nerve diaphragm preparation

5-Hydroxytryptamine causes depression of twitch height in the partially curarized rat phrenic nerve hemidiaphragm preparation

Safety factor at the neuromuscular junction

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