A method of stimulating different segments of the autonomic outflow from the spinal column to various organs in the pithed cat and rat

I The effects of pancuronium bromide on the cardiovascular system of the pithed rat were examined. Pancuronium had two effects, a short-lasting cardiovascular stimulation following injection and a longer-lasting potentiation of responses to sympathetic nerve stimulation. 2 The initial effect of pancuronium was compared with that of tyramine. The cardioaccelerator but not the pressor responses to both pancuronium and tyramine were significantly reduced following sympathectomy with 6-hydroxydopamine (6-OHDA). 3 The action of pancuronium in potentiating sympathetic nerve responses was compared with that of known blockers of the neuronal uptake of noradrenaline (NA). Pancuronium (1 mg/kg) and cocaine (0.5 mg/kg) potentiated cardioaccelerator and pressor responses to sympathetic stimulation. These effects of pancuronium could be obtained following adrenalectomy and during neuromuscular blockade with gallamine. Pancuronium and uptake blockers potentiated the cardioaccelerator response to NA, reduced the response to tyramine, but did not affect the response to isoprenaline. Pancuronium and uptake blockers potentiated the pressor response to NA, but did not affect the response to tyramine or clonidine. 4 Following sympathectomy with 6-OHDA, pancuronium failed to potentiate cardioaccelerator and pressor responses to NA. 5 These results are discussed in relation to two main cardiovascular effects of pancuronium; an indirect sympathomimetic action and blockade of the neuronal uptake of NA.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Sympathomimetic Effects of Pancuronium Bromide on the Cardiovascular System of the Pithed Rat: A Comparison With the Effects of Drugs Blocking the Neuronal Uptake of Noradrenaline

Docherty

McGrath

1978

“…Male Wistar rats (225-275g) were pithed by the method of Gillespie, MacLaren & Pollock (1970) and respired with 100% 02, 1 ml/100 g per beat, at a rate of 60/min. Heart rate was extracted from carotid arterial pressure, and the right jugular vein was used for drug injections.…”

Section: Methodsmentioning

confidence: 99%

An investigation of presynaptic α‐adrenoceptor subtypes in the pithed rat heart

Docherty

1983

“…The pithing rod was used to stimulate either the entire sympathetic outflow (Gillespie & Muir, 1967) or discrete segments of the spinal cord (Gillespie, Maclaren & Pollock, 1970). The tissues to which the sympathetic outflow was stimulated and the stimulus parameters used are shown in Table 1.…”

Section: Pithed Ratsmentioning

confidence: 99%

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Doxey

Everitt

1977

I The spinal sympathetic outflow to the eyelid, heart, splanchnic blood vessels, vas deferens and anococcygeus muscle was stimulated in pithed rats. 2 Clonidine inhibited sympathetic outflow to all of the tissues studied. The inhibitory effects of clonidine on cardiac nerves and hypogastric nerves were antagonized by phentolamine. 3 Clonidine produced a postsynaptic a-adrenoceptor agonist action on the eyelid, splanchnic blood vessels and the anococcygeus muscle. These effects were also antagonized by phentolamine. 4 The effects of clonidine, naphazoline and oxymetazoline on pre-and postsynaptic a-adrenoceptors were determined. 5 The presynaptic a-adrenoceptors employed were situated in either the sympathetic cardiac or hypogastric nerve terminals. Increases in diastolic blood pressure were used to assess concurrent postsynaptic a-adrenoceptor agonist activity. 6 The presynaptic a-adrenoceptor agonist potencies of clonidine, naphazoline and oxymetazoline were very similar on cardiac nerve terminals whereas on the hypogastric nerve terminals oxymetazoline was about 6 times more potent than either naphazoline or clonidine. 7 The results support the view that presynaptic a-adrenoceptors regulate transmitter release in sympathetic nerves. There appear to be subtle differences between the presynaptic a-adrenoceptors of different sympathetic nerve endings.