•618 



ADVENTURES IN RADIOISOTOPE RESEARCH 



In another experiment we administered a physiological dose of adre- 

 naline to the recipient rabbit, infusing all through the experiment 0.5 ml 

 •of saline per min containing 1 y of adrenahne per kgm body weight. 



42- 



28- 



14 



aarenoline dose 

 Pharmacological adrenaline dose 



I 

 fiO 



1 



120 

 Time m minutes 



~i — 

 160 



240 



Fig. 3. Effect of injection of adrenaline on the rate of extrusion of ^^Fe 

 from the plasma of the rabbit. 



In both experiments a marked increase of the disappearance of ^^Fe 

 from the circulation was observed under the action of adrenaline, the 

 effect of a pharmacological dose being the more pronounced one. 



DISCUSSION 



Following injection of labelled ions into the jugular vein there is a 

 large arteriovenous concentration difference which decreases exponenti- 

 ally with time (Pappenheimer, 1950; Schloerb, 1950). It is conceivable 

 that adrenaline accelerates this decrease and thus accelerates the extru- 

 sion of the labelled ions from the vascular bed. The rate of extrusion 

 may be determined by the rate of blood flow which is accelerated by 

 small doses of adrenaline. The fact that adrenaline influences markedly 

 the rate of passage of intravenously injected ^^P as phosphate or ^^Fe 

 circulating as ^-globulin into the extravascular space is not necessarily 

 to be interpreted as due to a change produced in the permeability of the 

 capillary wall. Phosphate which passes from the vascular bed into the 

 interspaces may repeatedly return into the former and escape again. 

 If. however, it took its way from the interspaces into the tissue cells, 



