COKONAKY PERFUSION OF EXCISED HEART 



13 



normal in the coronary artery ; the speed 

 of flow, however, owing to the viscosity co- 

 efficient of the Ringer-Locke being less than 

 that of blood, is not so deficient. 



The simple method here used (text-fig. 6) 

 for warming the perfusion fluid is that 

 devised by Professor J. A. Gunn {Jnl. of 

 Physiol vol. xlvi, p. 506, 1913), and text-fig. 

 6, 2, is copied from his original paper. 



Ohs. 6. Is in effect a modification of the 

 experiment byH. Newell Mirbin, Phil. 

 Trans. B. S., London, vol. 174, p. 663, 

 1883. The excised cat's heart beats quick- 

 est at 41-3° (H. N. Martin), i.e. about 200 per 

 minute. The lethal temperature is 44-5° C. 

 (H. N. Martin, 1890). 

 As exemplifying the kind of result obtained 



in this exercise with the rabbit's heart the 

 following actual class observation may be 

 given. Temperature in thermometer 13° C, 

 heart still beating ; temp. 15° C, 2 beats in 

 11" ; temp. 20° C, 6 beats in 10" ; temp. 

 25° C, 12 beats in 10"; temp. 35° C, 18 

 beats in 10" ; temp. 42° C, 22 beats in 10". 

 Knowlton and Starling, 1912 {Jnl. of 

 Physiol, vol. xliv, p. 217), have shown that 

 between the temperatures 26° and 40° the 

 rate of heart-beat in the mammalian lung- 

 heart preparation is a linear function of the 

 temperature. They remark on the fallacy 

 of assuming that this implies a direct tem- 

 perature 'coefficient' in the strict sense of 

 that term. 



EXERCISE III 



ADRENAL EXTRACT AND CHLOROFORM ON THE ISOLATED MAMMALIAN 

 HEART UNDER CORONARY PERFUSION 



I. See that the perfusion apparatus for the isolated heart is ready 

 (exerc. II). One of the tw^o reservoirs (text-fig. 6, i, k') contains 500 c.c. of 

 Einger-Locke fluid with 100 mg. of chloroform per litre. The other 

 reservoir contains Ringer-Locke fluid without CHCI3. 



II. Dissection. From the recently killed rabbit provided for you in the 

 tray remove the heart as in your previous perfusion experiment (exerc. II). 

 Connect the excised heart with the perfusion apparatus supplied with the pure 

 Einger-Locke fluid as in exerc. II, and obtain a graphic record of the beat of 

 the ventricle at a temperature of 35° C. 



III. Inject into the rubber supply-tube by a needle-syringe 1 c.c. of 

 •002 per cent. ' adrenalin '. The injection should be slow, e. g. occupy about 30". 

 Note and record effect on heart. 



IV. When the adrenal extract effect has subsided, open the supply-tube 

 from the CHCI3 reservoir and close that from^ the pure Einger-Locke solution. 

 The amplitude of the beat soon begins to diminish (text-fig. 11). When the 

 amplitude of the beat has been reduced to about one-quarter of its previous 



Obs. 8. 

 Adrenal 

 extract on 

 excised 

 mammalian 

 heart. 



Obs. 9. 

 Chloroform 

 on excised 

 mammalian 

 heart. 



