498 
On the Physiological Activity of Substances Indirectly Related to 
Adrenalin. 
By H. D. Dakin. 
(Communicated by Professor E. H. Starling, F.R.S. Received May 29,— 
Read June 8, 1905.) 
(From the Laboratory of Pathological Chemistry, Lister Institute of Preventive 
Medicine.) 
Since adrenalin itself possesses such remarkably definite physiological 
properties which are shared by the synthetical substance described in the 
preceding paper, it seemed to be of interest to try and trace some connection 
between their chemical structure and physiological action and, in particular, 
to see if the activity was to be ascribed to any particular chemical group or 
combination of groups. 
HO 
If the formula for adrenalin be either HOY CH(OH).CH,NHCH, or 
HO) 
HOK »>. CH(NH.CH,).CH,OH, we may artificially divide the molecule into 
two portions, an aromatic catechol nucleus and an oxyethylmethylamine 
(CH,OH.CH:NHCHsS) side-chain. The latter substance was prepared by heating 
glycolchlorhydrin with methylamine (1) and it was found that injection into 
a rabbit of quantities up to 10 milligrammes was followed by slight if any rise 
in blood-pressure. Injections of catechol, on the other hand, produce a great 
increase in pressure, as may be seen in fig. 1. This fact has also been 
observed by Miithlmann (2). The amount of substance required to produce an 
effect is considerable when compared with adrenalin, but a positive result 
seems significant. It will be seen from the tracing that the effect is prolonged, 
and it was found that subsequent injection of adrenalin produced no higher 
retinal pressure than that caused by catechol. When smaller quantities are 
injected into rabbits it is found that one does not obtain a rapid rise followed 
by a rapid fall, but both phases are prolonged and the stimulation is sub- 
maximal. 
The power of causing increased blood-pressure is shared by many other 
substances containing the catechol nucleus. Thus the two intermediate 
products in the synthesis of the “adrenalin-like” base described in the 
preceding paper are both physiologically active. In the case of chloracetyl- 
