No abstract

In a previous paper, Bain, Gaunt, and Suffolk (1937) described a biological assay method for following the course of adrenaline inactivation in vitro. Using this method they showed, among other things: (1) that adrenaline was only partially inactivated in cats' defibrinated blood, and that this was largely owing to the slow passage of some of the adrenaline into the red cells, whence most of it could be recovered by laking; (2) that the addition of tissue slices, particularly of liver, to a blood-adrenaline mixture, determined a relatively rapid and complete inactivation of the adrenaline.In some subsequent work, not published in full, Bain and Dickinson (1938) showed that the mean rate of adrenaline inactivation by liver slices, as indicated by the half-inactivation time, varied with the species: it was fastest for the guinea-pig and for man, slowest for the cat, dog, and mouse, and intermediate for the rat. The results from 16 samples of human liver were reported at that time. Three of these inactivated adrenaline so slowly as to seem in a different category from the others. As two of the subjects had suffered from arterial hypertension of non-renal origin it was suggested that delayed inactivation of the transmitter of adrenergic vasomotor nerve activity-then thought to be adrenaline-might be responsible for such forms of raised arterial blood pressure.The importance of noradrenaline was not, of course, recognized when these observations were made. It seemed desirable, therefore, in the light of subsequent events, to compare the behaviour of noradrenaline with that of adrenaline. This has accordingly been done by repeating some of the earlier work, but in parallel experiments in which both drugs were investigated at the same time under the same conditions. Most experiments were with human liver.A preliminary note on some of the results has already appeared (Bain and Batty, 1952). MATERIALS AND METHODSDrug Solutions.-A concentrated stock solution of (-)-adrenaline hydrochloride was made by dissolving a known amount of the synthetic laevo base (British Drug Houses, Ltd.) in the calculated amount of 0.1 N-HCl, and adjusting the final volume with distilled water so that the solution contained 10 mg. base/ml. From this a dilute stock solution, containing 1 mg. base/ml., was prepared as required. A standard adrenaline solution, containing 10 pg. base/ml., was freshly prepared for each assay from the dilute stock solution.Laevonoradrenaline was at first used as the hydrochloride, and later as the bitartrate monohydrateboth kindly supplied by Dr. M. L. Tainter. A stock solution, containing 1 mg. base/ml., was prepared by dissolving the appropriate amount of the salt in distilled water (I mg. base = 1.22 mg. hydrochloride = 1.99 mg. bitartrate). Standard solutions for the assays were prepared by dilution of this stock solution.Stock solutions were kept in the refrigerator. During the course of an assay the standard solutions were kept cool on ice.Blood-Liver-Amine System.-Apart from a few preliminary experiments, whe...