Effects of End‐tidal Concentrations of Cyclopropane, Halothane and Diethyl Ether on Peripheral Autonomic Neuroeffector Systems in the Rat

Abstract

1 The effects of the inhalation anaesthetics, cyclopropane, halothane and diethyl ether were examined on peripheral neuroeffector systems in the pithed and in the conscious rat. 2 In the absence of a suitable means of accurately quantifying doses of inhalation anaesthetics given to small animals, an apparatus was constructed whereby end-tidal gas samples were collected semi-automatically from the mechanically ventilated rat.3 Cyclopropane (15.3 and 29.3% end-tidal), halothane (0.20, 0.52 and 0.83% end-tidal) and diethyl ether (2% and 4% end-tidal) lowered the arterial pressure of the pithed rat. Heart rate was increased by diethyl ether 4%, decreased by halothane and unchanged by cyclopropane.4 While each anaesthetic depressed the pressor responses to sympathetic nerve stimulation, cyclopropane increased and halothane and diethyl ether depressed the pressor responses to exogenous noradrenaline. 5 Each anaesthetic reduced the motor responses of the smooth muscle of the colon to parasympathetic stimulation. 6 The significance of the effects on peripheral neuroeffector systems is discussed in relation to the overall circulatory changes produced by these anaesthetics in the whole animal.

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

“…This blockade of noradrenaline uptake by pancuronium is of obvious significance where pancuronium is employed as relaxant in experimental work where alterations in sympathetic transmission may be relevant. For example pancuronium has been employed to prevent muscle twitching in pithed rats (Gillespie et al, 1970;Gillespie & McGrath, 1973;; Clanachan & Muir, 1978). Of these examples, the only ones in which blockade of NA uptake by pancuronium might have affected the result were investigations of the effects of anaesthetics on autonomic responses in the pithed rat Clanachan & Muir, 1978).…”

“…For example pancuronium has been employed to prevent muscle twitching in pithed rats (Gillespie et al, 1970;Gillespie & McGrath, 1973;Clanachan & Muir, 1978). Of these examples, the only ones in which blockade of NA uptake by pancuronium might have affected the result were investigations of the effects of anaesthetics on autonomic responses in the pithed rat Clanachan & Muir, 1978).…”

“…For example pancuronium has been employed to prevent muscle twitching in pithed rats (Gillespie et al, 1970;Gillespie & McGrath, 1973;Clanachan & Muir, 1978). Of these examples, the only ones in which blockade of NA uptake by pancuronium might have affected the result were investigations of the effects of anaesthetics on autonomic responses in the pithed rat Clanachan & Muir, 1978). Fortunately, the effects of the anaesthetic agent ketamine, which is the only one suggested to affect NA uptake (Nedergaard, 1973), were also investigated on pithed rabbits and cats in which gallamine was the relaxant and the results were similar to those in the rat (Clanachan, McGrath & Mackenzie, 1976).…”

The Spinal Origin of the Sympathetic Nerve Fibres to the Vascular and Secretory Components of the Rat Submaxillary Salivary Gland

“…Electrical stimulation of the sympathetic spinal outflow in the pithed rat has been used to investigate the sympathetic innervation of a variety of tissues [see e.g. Gillespie and McGrath, 1973;Clanachan and Muir, 1978] but has not previously been used in salivary gland studies.…”