Noradrenaline Uptake Properties of the Anococcygeus Muscle of the Rat

The effects of neostigmine on noradrenergic transmission have been studied in the field stimulated, isolated anococcygeus muscle of the rat. In those muscles where the excitatory response to field stimulation was not completely inhibited by guanethidine (5 × 10−6 to 10−5m) or phentolamine (10−6m), atropine (5 × 10−8m) gave no further inhibition of the response. The shape of the response to field stimulation was altered in a dose‐dependent manner by neostigmine (5 × 10−7 to 5 × 10−6m), such that a ‘shoulder’ appeared during the relaxation phase. The ‘shoulder’, present at all stimulation frequencies tested between 3 and 40 Hz, was abolished by atropine (5 × 10−8 M) and unaffected by tubocurarine (10−6 m). Neostigmine (2.5 × 10−6 m), whether alone or in the presence of atropine (5 × 10−8 m), had no effect on the uptake or stimulation‐induced release of [3H]‐noradrenaline. Using electron microscopy, small Schwann/axon bundles close to smooth muscle cells rarely showed Cholinesterase staining, whereas larger bundles at the outer serosal aspects of the muscle exhibited dense staining. It is concluded that the observed effects of neostigmine are not due to a presynaptic effect on noradrenergic transmission.

Section: Choline Acetyltransferasecontrasting

confidence: 42%

Neostigmine augments responses of the rat anococcygeus muscle to field stimulation

Smith

Spriggs

1983

“…With these low concentrations uptake is likely to be mainly into adrenergic nerves, with no accumulation within smooth muscle (Nash et al, 1974). The results obtained in these experiments are illustrated in Figure 1 where maximum tissue:medium ratios of 5.4 ± 0.8 (s.e.…”

Section: Time Course Ofnoradrenaline Accumulationmentioning

confidence: 66%

Effects of Antidepressant Drugs on Noradrenaline Accumulation and Contractile Responses in the Rat Anococcygeus Muscle

Doggrell

Woodruff

1977

I The effect of a series of antidepressant drugs on noradrenaline accumulation was studied in the isolated anococcygeus muscle of the rat. 2 The most potent inhibitors of noradrenaline accumulation were nortriptyline, desipramine and protriptyline. Opipramol, trimipramine and iprindole were active only in high concentrations. 3 Contractions of the anococcygeus muscle produced by noradrenaline were strongly potentiated by nortriptyline, desipramine and protriptyline. Other uptake inhibitors were less active in potentiating the noradrenaline response. 4 Nortriptyline, in concentrations that potentiated the action of noradrenaline, reduced or abolished the response to tyramine.

“…The accumulation of noradrenaline from low concentrations of the amine by the rat anococcygeus muscle is predominantly neuronal (Nash, Gillespie & Robertson, 1974). Furthermore, following incubation with low concentrations of tritiated noradrenaline, all the radioactivity in the rat anococcygeus muscle behaves as authentic noradrenaline (Doggrell & Woodruff, 1977).…”

Section: Discussionmentioning

confidence: 91%

Effects of Drugs on the Accumulation and Spontaneous Release of Noradrenaline in the Rat Anococcygeus Muscle

Doggrell

Woodruff

1978

1The ability of drugs to inhibit noradrenaline accumulation and to release noradrenaline was studied in the isolated anococcygeus muscle of the rat. 2 Noradrenaline, tyramine, 2-amino,6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (ADTN), 2-amino,6,7-dimethoxy-1,2,3,4-tetrahydronaphthalene (dimethyl ADTN), and 5-hydroxytryptamine were all potent inhibitors of noradrenaline accumulation and potent releasers of noradrenaline. ADTN was accumulated by the rat isolated anococcygeus muscle. 3 Amphetamine and desipramine were potent inhibitors of noradrenaline accumulation but poor releasers of noradrenaline. 4 Methoxamine, oxymetazoline, acetylcholine, and angiotensin were poor inhibitors of noradrenaline accumulation and did not release noradrenaline. 5 The mechanism of action of these drugs is discussed.