17. On Myotonia 



What makes myotonia fascinating for the experimental re- 

 searcher is the fact that this hereditary degenerative disease of man 

 occurs in an experimental animal, the goat. Owing to the gener- 

 osity of Mr. R. Lombardi, of Philadelphia, Pennsylvania, the au- 

 thor is the happy owner of a small herd of such animals in which 

 myotonia is transmitted from generation to generation. G. L. 

 Brown and Harvey showed that this myotonic behavior is due to 

 the repetitive response of the nervous end plates of muscle. If the 

 nerve is excited by one electric shock, then, instead of producing 

 one wave of depolarization, the end plate fires a whole train of 

 them. Qjrresponding to this, if a resting myotonic animal wants 

 to make a sudden movement it stiffens up for a while and will 

 then start moving slowly with a spastic gait. In graver cases, the 

 animal may lose its balance and fall and will be unable to get up 

 for a while. As in human myotonia, exercise relieves the symptoms 

 and so once the animal starts moving it quickly shakes off its symp- 

 toms and behaves normally. No myotonic behavior can be elicited 

 in animals which find themselves in vigorous motion. 



Brown devised a simple method by which the gravity of the 

 disease can be measured and characterized by numbers, without 

 the use of sophisticated equipment or electronic hardware. The 

 method consists of hanging up the animal on belts just off the 

 ground. The animal is kept in this position for 15 to 30 minutes, 

 then is suddenly dropped to the ground. Previously, the animal 

 was trained to run to a certain place, say a corner where it could 

 find food and shelter. In the experiment the time is measured 

 which the animal needs to reach this place. Myotonic animals, 

 under the influence of the shock of the sudden fall, stiffen up and 



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