Biomedical subjects

D J Fishlock

Publications and source records attributed to D J Fishlock.

8 recordsLinked to original sources

PubMed1970

The action of angiotensin on the human colon in vitro.

1. The action of angiotensin on the circular and longitudinal muscle of the human colon has been studied in vitro. The ED50 value (g/ml) of circular muscle was 8.7 x 10(-8) and of longitudinal muscle 3.1 x 10(-8), while the corresponding figures for acetylcholine were 1.6 x 10(-6) and 1.1 x 10(-6), respectively. Angiotensin caused a sustained contraction associated with prolonged tachyphylaxis.2. As the action of angiotensin was not antagonized by atropine, hexa-methonium or procaine, angiotensin appeared to act directly on the smooth muscle of the human colon.3. Lidoflazine is not a specific antagonist of angiotensin.

Acetylcholine↗

PubMed1970

Pharmacologically active peptides and their effects upon the human colon in vitro.

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Acetylcholine↗

PubMed1969

Preiminary investigation of the pharmacology of the human internal anal sphincter.

The smooth muscle from the human internal anal sphincter has been investigated pharmacologically in vitro. The upper and lower parts of the sphincter responded to catecholamines in a similar manner. Noradrenaline caused contraction which could be antagonized by phenoxybenzamine. After phenoxybenzamine, noradrenaline caused relaxation which could be blocked by pronethalol. Isoprenaline caused relaxation which could be specifically prevented by pronethalol. Adrenaline was variable in its effect: low concentrations caused relaxation and high concentrations caused contraction. It is suggested that the anal smooth muscle contains alpha-adrenergic receptors subserving contraction and beta-receptors subserving relaxation. The lower part of the sphincter was generally insensitive to acetylcholine and nicotine whereas the upper part of the sphincter contracted with acetylcholine and regularly relaxed with nicotine. The nicotine response was antagonized by hexamethonium, procaine, and pronethalol. It is suggested that nicotine stimulated some part of the nervous mechanism in the upper part of the sphincter and that a catecholamine was the mediator of the inhibitory response.

Acetylcholine↗

PubMed1969