OKLAHOMA ACADEMY OF SCIENCE 17 



FURTHER OBSERVATIONS ON TONUS RHY- 

 THMS IN DIAPHRAGM MUSCLE 

 L. B. Nice and A. J. Neill, 1921. 



Abstract. 



Oscillations in diaphragm muscle have been observed by a num- 

 ber of workers in dogs and rabbits during normal sleep and under 

 anaesthesia. (1) The cause for these oscillations is considered to 

 be of central origin (2). 



We have noted these oscillations in urethanized dogs, rabbits, 

 cats and decerebrate cats. They may appear from one to seven 

 hours after the urethane, 2 grams per kilo of body weight, is ad- 

 ministeres by stomach. In an attempt to find whether they may 

 not be due in part to changes in the irritability of the muscle it- 

 self the following experiments were performed. Cats and dogs 

 aneshetised with urethane, 2 grams per kilo, were fastened back 

 down on the animal board and simultaneous records of the res- 

 piration and blood pressure made. The former was recorded by 

 attaching an S-shaped hook into the diaphragm about midway be- 

 tween the lateral chest wall and the central tendon of the diaphragm 

 and a thread passed from it over a pully to a writing lever as em- 

 ployed by Nice in former work. (3) The blood pressure was re- 

 corded from a femeral arter}' by means of a mercury manometer. 

 The brain of the animal was quickly pithed the phrenic nerves cut 

 and the peripheral end of one stimulated with make induction 

 shocks at the rate of 120 per minute. Then artificial respiration 

 was administered for about five minutes, after which a second 

 series of stimuli were applied to the Phrenic nerve and so on. 

 Under our experimental procedure the diaphragm gave tonus 

 rhythms similar in form to the oscillations that appear when the 

 narves are intact. This indicates that these oscillations may in part 

 be due to peripheral origin. 



BIBLIOGRAPHY 



(1) Mosse; Arciv. ital. de biol. 1886, VII, 48; ibid 1903, XL, 

 43. also McLeod : 



Physiology and Moderemistry in Modern Medicine. St. Louis 

 1908, 370. 



(2) McLeod loc. cit. 



(3) Nice, This Journal, XXXIII, 204; 1914 XXXIV, 326; 

 XXXV, 194. 



(4) Loc. cit. 



