EFFECTS OF SECRETION ON THE HEART AND VESSELS. 



11 



EFFECTS OF THE ADRENAL SECRETION ON THE CARDIO- 

 VASCULAR SYSTEM. 



THE ADRENAL SECRETION AND THE INHIBITORY CENTERS. 

 While removal of both adrenals is followed by a great fall of 

 blood-pressure and very feeble and rapid cardiac action, intra- 

 venous injections of suprarenal extract invariably cause marked 

 increase of the blood-pressure and equally marked slowing of 

 the heart-beat. The blood-pressure increase thus appears to be 

 due to the direct effect of the specific suprarenal principle; 

 but to account for the slowing of cardiac action we are led to 

 implicate the inhibitory action of the vagus. If the bulbar 

 center of this nerve be paralyzed by atropine, however, or the 

 vagus itself be cut, this inhibition ceases and quickening of 

 the heart-beat follows, accompanied by a still greater increase 

 of blood-pressure. Oliver and Schafer found 36 that the inhib- 

 itory action was exerted mainly upon the auricles, their beats 

 becoming gradually weaker; while the ventricular contractions, 

 though slower, were, in reality, stronger. 



Mooted points have arisen in this connection that have 

 entailed considerable divergence among physiologists; and, 

 curiously enough, when the various views entertained are 

 analyzed, none of them seem to harmonize with available ex- 

 perimental data. 



Cybulski, 37 after a series of careful experiments, reached 

 the conclusion that suprarenal extract acted upon the vaso- 

 motor centers of the medulla and spinal cord, first stimulating, 

 then paralyzing, them. Oliver and Schafer, 38 after equally 

 careful experiments, concluded that the extract induced reflex 

 stimulation of the inhibitory center by first causing powerful 

 constriction of the arterioles. This they thought accounted 

 for the slowing of the heart observed before the vagi were cut, 

 and physiologists have generally accepted the conclusion that 

 the inhibitory center is stimulated. Indeed, even the more 

 recent and carefully conducted physiological researches have 

 sustained this opinion; Wallace and Mogt, 39 for instance, were 



36 Oliver and Schafer: Journal of Physiology, xviii, 1895. 



87 Cybulski: Gazeta Lekarska, March 23, 1895. 



38 Oliver and Schafer: Journal of Physiology, vol. xviii, p. 230. 



89 Wallace and Mogt: American Physiological Society Proc., Dec. 28, 1898. 



