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Biomedical subjects

I Marshall

Publications and source records attributed to I Marshall.

At least 127 records · Page 7Linked to original sources
PubMed1977

An inhibitory role for noradrenaline in the mouse vas deferens.

1 Noradrenaline (0.1-3.0 muM) inhibited the twitch responses to single pulse field stimulation of the isolated vas deferens of the mouse. The higher concentrations of noradrenaline (ca. 0.3-3.0 muM) were required to make the tissue contract.2 Phentolamine (10 muM) abolished the contractor response to higher concentrations of noradrenaline and antagonized the inhibitory effect of lower concentrations on the twitch response.3 Propranolol (10 muM) potentiated both the contractor and the inhibitory effect of noradrenaline on the twitch response.4 Isoprenaline (0.1-3.0 muM) and salbutamol (1.0-3.0 muM) both inhibited the twitch response. Their effects were antagonized by propranolol (10 muM), but not by practolol (10 muM).5 The effects of uptake(1) and uptake(2) blocking agents were determined. Cocaine (10 muM) reduced the size of the twitch response in 2 out of 4 experiments. Imipramine (0.18 muM) also reduced the size of the twitch, as did oestradiol (3.7 muM) and a combination of cocaine and oestradiol.6 Contractor responses to exogenous noradrenaline showed tachyphylaxis, but when this was not very marked, the response could be shown to be potentiated by uptake blocking agents.7 The inhibitory effect of noradrenaline on the twitch response was greatly potentiated by cocaine (10 muM) and much less so by oestradiol (3.7 muM).8 It is concluded that the transmitter responsible for the twitch response is either an unknown substance released from the sympathetic neurone, or noradrenaline acting upon a receptor with none of the characteristics of known alpha- or beta-adrenoceptors. In either case, noradrenaline can inhibit the output, probably by stimulation of presynaptic alpha-adrenoceptors.

Albuterol↗
PubMed1974

Acute and chronic morphine treatment and the hydroxylation of (1-14C)-L-tyrosine in the mouse brain.

Tyrosine hydroxylase activity in slices of caudate nucleus was increased by morphine (100 mg/kg i.p.) administered to naive mice. During chronic treatment with morphine tolerance developed to this effect and 36 h after the final chronic morphine injection there was a decrease in enzyme activity in this area. There was no change in tyrosine hydroxylase activity in slices of diencephalon, brainstem or parietal cortex from either naive or morphine tolerant mice. There- fore, changes in tyrosine hydroxylase activity, measured in vitro, could account for the changes in dopamine synthesis, but not noradrenaline synthesis, produced by morphine in vivo.

Animals↗