On the physiological action of pyridine / by T. Lauder Brunton and F.W. Tunnicliffe.

  • Brunton, Thomas Lauder, Sir, 1844-1916.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: On the physiological action of pyridine / by T. Lauder Brunton and F.W. Tunnicliffe. 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.

    8/15 (page 274)
    action on sensory nerve endings and exerts this both when injected into the general circulation and when applied locally. A 5 % solution of pyridine applied for two minutes to the right leg of a decapitated frog weighing 17 grammes produced complete local ansesthesia which lasted for 20 minutes. When pyridine is introduced into the general circulation in doses which are insufficient to cause paralysis of the sensory centres of the cord (see below), the order of the onset of the skin anaesthesia seems to be hind limbs, then fore limbs, and then trunk. Sensory spinal centres. Pyridine paralyses the sensory centres of the cord in frogs, when injected into the circulation in doses of from '09 to -1 gramme per 100 grammes body weight. The skin becomes anaesthetic as described above, but in addition, stimulation of the central end of the sciatic by an induced tetanizing current remains inactive. Motor centres and motor conductivity of the cord. If the spinal cord of decapitated and pyridined frog be exposed and stimulated directly by a weak induced tetanizing current, convulsive contractions will take place ; these contractions will first make their appearance at the level of the stimulation, but these will be immediately followed by contraction of the lower limbs. Both of these sets of convulsive contractions will take place at a stage of the poisoning when neither irritation from the skin nor irritation from the central end of the divided sciatic, will cause any reflex action. Thus if we consider the different parts of the reflex arc, sensory nerve endings, afferent nerve, sensory spinal cells, intermediate fibres, motor cells, efferent nerve, and lastly motor nerve endings, we see that pyridine, when introduced into the general system, paralyses the sensory nerve endings, the sensory spinal centres or possibly the intermediate fibres, leaving the other constituents of the arc intact at least in frogs. In guinea-pigs it would seem, from the fact that occasionally more or less general tremor occurred in response to strong peripheral irrita- tion, that, either the activity of the motor centres is somewhat increased or that some change has taken place in the conducting activity, the relative resistance, of the intermediate fibres. Automatic respiratory centre. Pyridine in relatively small doses •05—T gramme pro kilo body weight has a marked action on the automatic respiratory centre. The respirations become slower and shallower, they then become irregular and inspiration takes jdace in two phases with a slight pause between them. This causes a notch in the otherwise continuous ascent of the lever making the descent of the