INFLUENCE OF THE LIVER ON THE SHOCK PRODUCED BY EXTRACTS OF CERTAIN PARASITES

Abstract

Extracts of Ascaris suum and hydatid fluid produce profound hypotension (shock) when injd. intraven. in appropriate doses into dogs. Accompanying the decrease of arterial blood pressure there was a significant increase of the pressure of the portal system and grossly there was marked congestion of the liver and the intestines. The hepatic congestion was vascular since histologic examination of hepatic tissue showed the parenchyma to be free of hemorrhage. After recovery from a given injn., of either Ascaris extract or hydatid fluid, reinjn. of the same dose did not produce any change in the blood pressure (tachy-phylaxis). That the liver was chiefly responsible for the reaction was shown by the fact that huge doses of hydatid fluid or purified Ascaris extract had little or no effect on the blood pressure in hepatectomized dogs. The crude extract of Ascaris, however, produced in liverless dogs a marked fall of blood pressure, from which all the animals recovered. After recovery they were refractory to the same or 4 times the original dose of the extract. Dogs whose hepatic circulation had been altered by an Eck fistula and ligation of the hepatic-artery showed a small but very prolonged decrease of the arterial blood pressure. Dogs with Eck fistulas alone responded to the injns. of the substances from the parasites in the same-manner as did normal dogs. Newborn pups responded to intraven. injn. of the purified extract with a markedly decreased blood pressure but pups heavily infected with Toxocara canis were immune to the extract. The isolated perfused liver of the dog reacted to the injn. of Ascaris extract by a marked decrease of hepatic outflow and very intense congestion. Blood taken from a liverless dog after a large dose of Ascaris extract and injected into a normal sensitive dog produced the typical response of the blood pressure but when blood was taken from a normal dog at the depth of its hypotension from an injection of Ascaris extract and injected into a liverless dog it was without effect on the blood pressure, thus suggesting that the mechanism is primarily mechanical and only secondarily chemical. From the evidence presented in this communication it may be concluded that congestion of the liver is the principal cause of the fall of blood pressure produced by Ascaris extract and hydatid fluid in susceptible dogs but other organs may also react as demonstrated by injection of the crude extract and deproteinized extracts of Ascaris into liverless dogs.