The haemorrhagic exudate and its possible relationship to neurogenic inflammation

The morphological effects of an aqueous solution of Nistatin, of Clostridium septicum and Tityus serrulatus toxins, of Bothrops jararaca and Agkistrodon piscivorus venoms on the vessels of the tendinous portion of the diaphragm were investigated in guinea-pigs. It was demonstrated that all these substances, when injected intrapleurally induced not only an increase in the permeability of venules but also haemorrhages originating at this segment of the microcirculation. Red cells were shown to escape from venules either by diapedesis or from restricted areas of these vessels which showed intense ultrastructural disorganisation of the vessel wall. Previous treatment of the animals with steroidal or non-steroidal anti-inflammatory drugs or with anticoagulants and chemotherapeutic drugs did not abolish the effect of these irritants. Electrical or chemical stimulation of the phrenic nerve had effects on the microcirculation of the diaphragm similar to those of Nistatin, toxins and venoms. Because of these findings and because Nistatin when injected intrapleurally induces an intense perineuritis of the phrenic nerve, a tentative hypothesis is proposed linking haemorrhagic exudation to the antidromic stimulation of sensitive nerves.