The effect of systemic anaphylaxis on mesenteric lymph flow in anesthetized rats

Abstract

The anaphylaxis‐induced fluid extravasation in splanchnic vascular bed was determined by measuring the mesenteric lymph flow (Qlym) during anaphylactic shock in anesthetized rats. Blood pressure (BP), portal venous pressure (PVP), and Qlym were measured. An injection of the ovalbumin antigen into the sensitized rats (n=10) caused a decrease in BP from 125 to 37 mmHg at 10 min, while an increase in PVP by 21 cm H2O at 2 min. Qlym increased 3.3‐fold baseline at 2 min, followed by a return to the baseline within 12 min. The lymph protein concentrations increased after antigen, which indicated increased vascular permeability. In the non‐sensitized rats (n=10), PVP was mechanically increased in a manner similar to that of the antigen‐challenged rats. Unexpectedly, this PVP elevation caused a similar increase in Qlym, but the lymph protein concentration decreased. In separate sensitized rats (n=5), the mesenteric arterial flow was much decreased after antigen, as compared with the PVP elevated rats (n=5), suggesting reduced splanchnic vascular surface area during anaphylaxis. In conclusion, systemic anaphylaxis in rats causes an increase in Qlym by increased vascular hydrostatic pressure due to portal hypertension, and by increased vascular permeability. However, this increased extravasation is relatively small probably due to decreased vascular surface area, and is observed transiently only soon after antigen.