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

  • Paton, William D. M.
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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    this response is reduced and may even be absent. On the other hand, these reflex mechanisms also serve to limit such changes in blood-pressure in the normal animal as those caused by the injection of acetylcholine or adrenaline; hence the injection of hexamethonium actually increases and prolongs the action of adrenaline and acetylcholine. Action on effects of vagal stimulation Pentamethonium and hexamethonium will also inhibit the effects of stimulation of the peripheral stump of the vagus, cut in the neck, on the heart rate and blood- pressure. In the experiment of Fig. 10, the right vagus was faradized for 10 sec., Fig. 10.—Cat,chloralose; blood-pressure. In¬ travenous injections: (a) and (r) right vagus stimulated 'at 10/sec. for 10 sec. ; (b) and (d) injection of 10 tig. acetylcholine. Between (b) and (c) 10 mg. hexametho¬ nium iodide. C6 lOmg fa) (it) I (c) (d) Slim Ach lOpg Slim Ach.lO^g causing a fall in blood-pressure and considerable slowing of the heart; 10 /xg. acetyl¬ choline caused a similar response. Then 10 mg. pentamethonium was injected intravenously. Two minutes later, faradization of the vagus was ineffective, although acetylcholine had the same action as previously. Exactly the same results were obtained when hexamethonium or tetramethonium was used. These . . 240 experiments again provide evidence that the action of these drugs is restric¬ ted to ganglia, and does not extend to the effector organ. Effect on the heat output of the rabbit's ear The heat-flow meter, recently de¬ vised by Hatfield (1950), offered a simple means of recording an increase in blood flow through a rabbit’s ear as an increase in the rate of loss of heat from the ear to the environment. Fig. 11 shows the result of injection of 10 mg. pentamethonium iodide per kg. into one ear vein of an animal to whose other ear the recording disk was fastened. After a brief latency, the heat output of the ear rose abruptly, Hedt.-out.put (kg cdl/ m2/ hr.)'40 I 20 IOO 80 60 ( 40 20 — • — • it . i j i-1 i 1-i i ‘ j l 2 3 4 S 6 7 6 9 lO It 12 13 Time (minutes ) Fig. 11.—Rabbit. Heat output from the ear, recorded by Hatfield heat-flow meter. At arrow, 10 mg. pentamethonium iodide per kg. intravenously.