INFLUENCE OF CHAIN‐LENGTH UPON SOME PHARMACOLOGICAL PROPERTIES OF S‐ALKYL ISOTHIOUREAS

EFFECTS OF SOME S‐ALKYLTHIOURONIUMS AND RELATED COMPOUNDS ON THE OSMOTIC FRAGILITY AND THE MEMBRANE EXPANSION OF HUMAN ERYTHROCYTES

“…The reduction in critical haemolytic volume obtained with antihaemolytic concentrations of S-10 may therefore be due not only to an increased efflux of potassium ions from the cell but also to a de-creased influx of sodium ions. Such an unspecific action on membrane permeability would explain why S-10 has been found in experiments on smooth muscle preparations (Fastier & Reid, 1952;Corbett, Bills & Fastier, 1974) …”

“…Ascent of a series results in the intensification of actions which can be loosely described as 'depressant', e.g., vasodilator and other spasmolytic actions, inhibition of such enzymes as monoamine oxidase. This has been explained (Fastier & Reid, 1952) by supposing that some actions of amidines are not exerted in the same phase as the one in which the drug is administered. With increasing chain-length there should be an increasingly favourable distribution of the drug between an aqueous phase and the 'biophase' up to a cut-off imposed by insufficient solubility in water.…”

Observations on ‘fade’: a complication of the contractile response of smooth muscle to a large dose of an agonist

“…With a large dose of the agonist, however, the contraction may 'fade' at least temporarily from a rapidly attained peak. Fade has been observed in experiments with the ileum and taenia coli of the guinea-pig (Fastier & Reid, 1952;Paton, 1961;Durbin & Jenkinson, 1961;Ariens, Simonis & van Rossum, 1964). It has been obtained with isotonic recording, especially with heavy loading (Fastier & Reid, 1952;Ariens et al, 1964) and auxotonic recording (Paton, 1961).…”

“…Fade has been observed in experiments with the ileum and taenia coli of the guinea-pig (Fastier & Reid, 1952;Paton, 1961;Durbin & Jenkinson, 1961;Ariens, Simonis & van Rossum, 1964). It has been obtained with isotonic recording, especially with heavy loading (Fastier & Reid, 1952;Ariens et al, 1964) and auxotonic recording (Paton, 1961). Similar phenomena have been noted in experiments on the rectal caecum of the fowl (Barsoum & Gaddum, 1935) and on vascular smooth muscle (Fara, 1971;Godfraind & Kaba, 1972).…”

“…Since earlier experiments had indicated that fade was more evident the higher the tension applied to the muscle strips (Fastier & Reid, 1952), a tension equivalent to a 2 g weight load was applied to the strip. Either isometric or isotonic changes were recorded, the former with an isometric strain gauge, the latter with a simple lever.…”