The physiological action of choline and neurine / by F.W. Mott and W.D. Halliburton.

  • Frederick Walker Mott
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: The physiological action of choline and neurine / by F.W. Mott and W.D. Halliburton. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Tlie injection of nicotine is followed by increased respiratory actions, and rise of blood-pressure, but if the dose is repeated again and again, this effect becomes less and less, and finally nil, and the animal has to be kept alive by artificial respiration.^ But when this stage has been reached, the animal must not be considered to be fully nicotinised, for stimulation of the central end of the divided sciatic still con- tinues to j^roduce a great rise of blood-pressure. At last, however, the animal is fully under the influence of the drug. In the case of one cat we had to inject 115 milligrammes of nicotine, in another 275 milligrammes of nicotine before this stage was reached.! Even after this stage is reached, the blood-pressure still continues to be compara- tively high ; the subsequent injection of choline (fig. 33), or of cerebro-spinal substance (fig. 32) produces the usual fall of arterial pressure. It will be noticed in this, as in some of the previous tracings obtained after the elimination of the central nervous system, that the recovery of the blood-pressure to its usual level is exceedingly slow. 4. The last method employed in this branch of the research has been to apply the dmg locally to the intestinal vessels. This can be done in the frog by watching the mesenteric vessels with the microscope and then bathing them with the drug; or in the mammal the drug can be applied locally to the loop of intestine within the oncometer, and the effect can l>e watched with the eye through the glass lid of the instrument, or the eftect can be registered graphically. These effects confirm the statements already made that choline and cerebro-spinal substance act locally on the neuro-muscular mechanism of the blood vessels. In order to obtain the effect with the oncometer, it was first necessary to warm the drug to the temperature of the animal’s body.| A hole was previously made through the side of the oncometer. This was closed with a cork, through which a stiff wire was passed ; at the end of the wire was a little open porcelain vessel filled with a solution of the drug ; on turning the wire through 180°, the contents of the porcelain spoon were u])set over the intestinal loop. The next figure shows the result. There is a rise of the oncometer lever, indicating dilatation of the vessels ; this continues to increase, until the glass lid of the onco- meter is raised, and the drug washed away with saline solution. The local effect on a loop of intestine, however, is not sufficient to cause any appre- ciable change in general blood-pressure. Fig. 34 shows the effect of 10 cub. centims. of cerebro-spinal fluid ; a 0‘2 per cent, solution of choline hydrochloride acts in exactly the same way. * See Moop.e and Row, ‘Journal of Physiology,’ vol. 22, p. 275, 1897-8. t The resistance of the cat, and still more so, the dog, to nicotine has already l)een pointed out hy Langley, ‘Journal of Physiology,’ vol. 20, p. 240, 1897-8. X In order to minimise the effects of shock when using the intestinal oncometer, we always kept the animal on a hot water tin, and surrounded it with cotton wool.