The significance of the supra-renal capsules in the action of certain alkaloids / by H.H. Dale and P.P. Laidlaw.

  • Dale, Henry H. (Henry Hallett), 1875-1968.
Date:
[1912]
Catalogue details

Licence: Public Domain Mark

Credit: The significance of the supra-renal capsules in the action of certain alkaloids / by H.H. Dale and P.P. Laidlaw. Source: Wellcome Collection.

    18/30 (page 16)
    on the operated side the pupil became maximal and remained so for the rest of the experiment, in spite of vigorous artificial respiration, to exclude the possibility of an asphyxial effect, and a further injection of 4 mgms. of pilocarpine. In the normal eye a secondary dilatation followed the constrictor phase, but the pupil became smaller again under the further dose of pilocarpine. The pupil on the operated side being already maximal, after the first dose of pilocarpine, no further dilatation with nicotine was possible. After the immediate effects of the first injection of nicotine had passed off, however, the nictitating membranes came somewhat forward, as normally happens. It was then possible to observe, with a further injection of nicotine (3 mgms.), that the nictitating membrane was retracted more rapidly and fully on the operated than on the normal side. Although, therefore, the experiment was not in all respects satisfactory, clear information was obtained on the main point under investigation: it was proved that the sympathetic effects of pilocarpine and nicotine on the eye, already known to be produced in the absence of the superior cervical ganglion, are still produced after degeneration of the post-ganglionic fibres, and produced apparently with supernormal intensity. In other words, the effect resembles that of adrenine, and one can so far sum up the sympathetic effects of this group of alkaloids on the eye as a combination of action on the cells of the superior cervical ganglion with a peripheral elfect of the type which one of us has elsewhere termed “ sympathomimetic.” Effects on the isolated iris. Again, however, as in the case of the uterus, these effects of the nicotine alkaloids are not seen on the isolated cat’s iris. The preparation is made as follows. A cat is killed, by pithing the brain through the foramen magnum and the eyes are excised as quickly as possible. The cornea and sclerotic are cut through close to the ciliary region. The vitreous humour and lens are removed, leaving only a ring of sclerotic with the ciliary body and iris. The preparation is dropped into a beaker of Ringer’s solution kept at 37°—39° C., through which oxygen is bubbled. The beaker may conveniently be stood in a white enamelled vessel also containing Ringer’s solution, kept at the same temperature by a small flame underneath. The preparation is arranged with the anterior surface of the iris uppermost. The drug to be tested is added to the beaker, due precautions being taken not to alter the temperature of the contents, and, when its effect is complete, the preparation can be washed in the solution in the outer vessel, while that in the beaker is changed.