A Muscarinic Inhibition of the Noradrenaline Release Evoked by Postganglionic Sympathetic Nerve Stimulation

Effect of Muscarine on Release of Catecholamines From the Perfused Adrenal Gland of the Cat

“…Effect ofmuscarine on responses induced by highK +, nicotine and veratridine Acetylcholine inhibits release of NA from adrenergic nerve terminals, and this inhibition has been attributed to an activation of inhibitory muscarinic recep- tors on the sympathetic nerve terminals (Loffelholz & Muscholl, 1969). It was of interest, then, to examine the effect of muscarine in the cat adrenal gland on secretory responses to various agonists.…”

“…Thus, Muscholl and his colleagues have shown that activation of muscarinic receptors reduces the release of noradrenaline from sympathetic nerves by either electrical stimulation or high potassium (Loffelholz & Muscholl, 1969, Dubey, Muscholl & Pfeiffer, 1975.…”

Sixth Gaddum Memorial Lecture National Institute for Medical Research, Mill Hill, January 1977

“…As shown schematically in Figure 7, the following presynaptic receptors have been postulated: (a) muscarinic inhibitory cholinoceptors (Loffelholz and Muscholl, 1969;Steinsland, Furchgott & Kirpekar, 1973;Langer, Enero, Adler-Graschinsky, Dubocovich & Giorgi, 1976); (b) dopamine inhibitory receptors (Langer, 1973;Enero & Langer, 1975;Long, Heintz, Cannon & Kim, 1975); (c) opiate inhibitory receptors, which are activated by morphine and also by the naturally occurring pentapeptides met and leu-enkephalin (Hughes, Kosterlitz & Leslie, 1975 (Hedqvist, 1970;Stjmrne, 1973;Dubocovich & Langer, 1975;Hedqvist, 1976); (e) adenosine inhibitory receptors (Hedqvist & Fredholm, 1976); (f) angiotensin II facilitatory receptors (Starke, 1970(Starke, , 1971Hughes & Roth, 1971) and (g) nicotinic facilitatory receptors (Lindmar, Loffelholz & Muscholl, 1968;Loffelholz, 1970).…”

Effects of McN‐A‐343 and DMPP on the uptake and release of 3H‐noradrenaline by guinea‐pig atria

“…Our findings suggest that the actions and efflux of the released noradrenaline may be enhanced by the additional effect of DMPP in inhibiting re-uptake of the released noradrenaline. The release of noradrenaline from rabbit heart by nicotinic drugs, including DMPP, is terminated by a blockade of release which has been termed 'autoinhibition' (Loffelholz & Muscholl, 1969, Loffelholz, 1970a. In guinea-pig atria, cocaine abolishes responses to DMPP and nicotine (Bhagat, 1966) and in the rabbit pulmonary artery the noradrenaline-releasing action of nicotine is reduced by phenoxybenzamine, desipramine and cocaine (Su & Bevan, 1970).…”