Physiology. — "On the Efiect of Lohelin') on the Rise of Blood 

 pressure by Nicotin'. By W. Storm van Leeuwen and 

 C. DE LiND VAN Wijngaarden. (Communicated by Prof. H. 

 Zwaardemaker). 



(Communicated in the meeting of September 29, 1917). 



When one of us was carrying out an inquiry into the effect of 

 various lobelia preparations, the results of wliich will be published 

 in the "Nederlandsch Tijdschrift voor Geneeskunde", we found that 

 the rise of bloodpressui-e, evoked in a cat by nicotin, was greatly 

 influenced by a previous injection of lobelin. We decided to look 

 more closely at this phenomenon, as we presumed this to be an 

 instance of Bürgi's "potentiation" (Potenzierung) i.e. the effect of a 

 mixture of two poisons is stronger than is expressed by the algebraic 

 sum of the action of the component parts. The facts revealed in 

 this inquiry are chiefly the following: 



When a cat, which — to eliminate central influences — had been 

 previously decapitated after Sherrington, was given intravenously a 

 small dosis of nicotin, e.g. 0.1 mgr., a fall of the bloodpressure 

 generally ensued, which was succeeded by an increase of bloodpressure. 

 The first phenomenon probably results from an inhibiting influence 

 of nicotin upon the heart, the second from a stimulation of 

 sympathetic ganglia, causing a constriction of the bloodvessels. The 

 course of such a nicotin-curve is irregular. When, however, from 1 

 to 2 mgr. of atropin has been previously injected, the fall of the 

 nicotin-curve disappears completely or partly and oidy the rise 

 remains. The current opinion is that the first fall in the nicotin-curve 

 is effected by a stimulation of the vagus by nicotin, which is again 

 inhibited by atropin. Why, in some cases, the atropin does not 

 prevent the primary fall, has not yet been explained. 



') When our supply of lobelin was exhausted and none could be procured in 

 Holland, Prof. Schoorl liad a fresh supply prepared in his laboratory, for which 

 we acknowledge our indebtedness. 



