Compound 48/80 : a potent hitamine liberator / by W.D.M. Paton.

  • William Paton
Date:
[1951?]
Catalogue details

Licence: In copyright

Credit: Compound 48/80 : a potent hitamine liberator / by W.D.M. Paton. Source: Wellcome Collection.

    5/14 (page 501)
    Release of histamine in the cat.—The delayed depressor response, the “ self¬ potentiation,” the peripheral vasodilatation and the rise in haematocrit are charac¬ teristic of histamine liberators (Macintosh and Paton, 1949). Experiments were therefore made to test whether histamine could be demonstrated in the plasma of animals receiving the drug. Table I gives the results from two such experiments. The plasma before the injection of Compound 48/80 had a histamine equivalent of 0.05 ng./c.c., or less. After the injection of 0.5 or 0.7 mg./kg. of Compound 48/80 TABLE I Exp. Dose of Assay method Histamine equivalents (/xg./c.c.) of plasma before and after injection of 48/80 48/80 Time after injection of 48/80 (minutes) Before 1 5 10 30 1 0.5 mg./kg. 2 0.7 mg./kg. Guinea-pig’s ileum / Guinea-pig’s ileum \ Cat’s B.P. 0.05 0.5 — 0.32 0.22 <0.05 0.9 ^0.5 — <0.1 \ <0.1 1.0 0.3 — <0.1/ intravenously, it rose within a minute to 0.5 /xg./c.c. and 1.0 /xg/c.c. respectively in the two tests. That the active substance in the plasma was in fact histamine was shown by the facts that assays on cat’s blood-pressure and on guinea-pig’s ileum agreed quantitatively, and that small doses of mepyramine abolished its effect on guinea-pig ileum (Fig. 2b and g) and on the cat’s blood-pressure (Fig. 3b and h) proportionately with the effect of an equipotent dose of histamine. Atropine did not reduce the effect of the plasma on the gut. Fig. 2.—Guinea-pig’s ileum. Effects of plasma from Exp. 2, Table I. (a), (b), (c), (d), 0.1 c.c. plasma withdrawn respec¬ tively before and 1 min., 5 min., and 30 min. after the intra¬ venous injection of Compound 48/80. (e) 0.06 n-g. histamine. Mepyramine 0.3 fig. added to bath thereafter. (/) 0.06 /xg. histamine, (g), (h), (/'), 0.1 c.c. of 1 min., 5 min., and 30 min. plasma respectively. a b c d e f q h i Fig. 3.—Cat, chloralose. Arterial blood-pressure. Intravenous injections. Effects of plasma from Exp. 2, Table I. (a), (b), (c), (<7), 0.25 c.c. plasma withdrawn before and 1 min., 5 min., and 30 min. after intravenous injection of Com¬ pound 48/80. (<?) 0.05 fjug. histamine. (/) 0.3 ng. hista¬ mine. Between (/) and (g), 0.05 mg. mepyramine. (g) 0.3 fig. histamine. (//) 0.25 c.c. of 1 min. plasma.