The Changes in the Venous Bloodflow on Administration of Amyl Nitrite

PLA~E XXIV. The question as to whether the characteristic changes in general blood-pressure resulting from the introduction of amyl nitrite are caused by a direct inhibitory influence upon the plain muscle cells of the peripheral vascular channels or whether they are referable to an action of this drug upon central nervous structures has been investigated repeatedly. By stimulation of the splanchnic nerve, Bernheim ~ succeeded in raising the blood-pressure of animals poisoned with amyl nitrite, and concluded, therefore, that the con-tractile elements of the blood vessels are not affected by the drug. The view that amyl nitrite exerts prefiminently a central influence is also shared by Filehne. ~ Atkinson 4 having established an artificial circulation through the aorta, observed a more ready outflow of fluid whenever amyl nitrite was added to the perfusion liquid. Under similar conditions, MarshalP obtained an increase of flow through the excised kidney. A ready means of studying the influence of amyl nitrite upon the circulation seemed to be furnished by the recording stromuhr. With the help of this instrument, we thought it possible to follow accurately the diverse quantitive changes of the bloodstream which this drug might be capable of producing, and to bring these changes at the same time into relation with the variations in blood-pressure. W e selected the capillary field of the femoral artery for the de-1Received for publication January 25, I9IO.