Paralysis of autonomic ganglia by methonium salts / by W.D.M. Paton and E.J. Zaimis.

  • William Paton
Date:
[1951?]
Catalogue details

Licence: In copyright

Credit: Paralysis of autonomic ganglia by methonium salts / by W.D.M. Paton and E.J. Zaimis. Source: Wellcome Collection.

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    had been washed out, it was filled with saline, one cannula was occluded, and the other cannula was connected to a sensitive bellows recorder. Experiments on the peristaltic reflex of the rabbit’s ileum were made by the method of Trendelenburg (1917). Intravenous injections were made through a glass cannula tied into the jugular or femoral vein. Vasodilatation in the rabbit’s ear was recorded by means of Hatfield’s (1950) heat-flow meter; this consists of a tellurium disk 1 cm. diameter, with copper gauze welded to either side. When placed on a surface losing or absorbing heat, a potential difference, easily recorded by a galvanometer, is set up between the two thermo-junctions so formed, such that for a heat loss of 100 kg. cal./sq. m./hour an electromotive force of approximately 70 microvolts is obtained. The disk is stuck to the surface of the ear by a layer of cellulose tape. Methonium salts, tetraethylammonium, and tetramethylammonium were all given as iodides, and nicotine as tartrate. Doses are all given in terms of the salts. Results Action on cat's superior cervical ganglion If the cut peripheral end of the cervical sympathetic in the cat is stimulated electrically at a frequency of 10/sec., a well-sustained contraction of the nictitating membrane can be recorded. This is depressed or abolished by the injection intra¬ venously of substances which block transmission in the superior cervical ganglion. Such a relaxation can be produced by the members of the methonium series from C3 to CIO, but with various degrees of activity; pentamethonium and hexamethonium are particularly effective, and doses of 0.02 mg./kg. injected intravenously sometimes produce a detectable effect. Fig. 1 illustrates this action for hexamethonium in a dose of 0.23 mg./kg. Fig. 1.—Cat, chloralose. Contraction of nicti¬ tating membrane to preganglionic excita¬ tion at 10 shocks/sec. (above) and blood- pressure (below), (a) At arrow, 0.23 mg. hexamethonium iodide per kg. intravenously; (b) at arrow, 1.5 mg. tetra ethyl ammonium iodide per kg. intra¬ venously. The sensitivity of the ganglion depends on the nature and duration of the preganglionic excitation. For instance, if stimulation at a rate of 10/sec. is maintained for 15-20 min., the proportionate reduction of the height of contraction of the nictitating membrane by a given dose of pentamethonium or hexamethonium may be 20-30 per cent greater at the end than at the beginning of excitation. Similarly, a ganglion which receives continous stimulation is more sensitive to these drugs than
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