Hepatic microvascular pressure during anaphylactic shock in anesthetized rats.
OBJECTIVE
Hepatic venoconstriction plays a significant role in anaphylactic hypotension in anesthetized rats. The purpose of this study is to determine whether the primary site of anaphylactic venoconstriction in the liver venous circulation occurs prior to or distal to the sinusoidal capillaries. We also determined whether the hepatic blood volume is increased during anaphylactic hypotension.


METHODS
We measured, using a servo-null micropipette pressure-measuring system, the hepatic venular transmural pressure (P micro hv) at the liver surface of anesthetized rats sensitized with the antigen of ovalbumin (1 mg). We also measured the liver lobe thickness, using the ultrasonic crystal dimension measuring system. Anaphylactic hypotension was induced by an intravenous injection of 0.6 mg ovalbumin.


RESULTS
When the antigen was injected, the systemic arterial pressure decreased profoundly from 118+/-9 to 45+/-4 mm Hg, which was accompanied by an increase in Ppv and P micro hv: P micro hv only transiently increased from 3.1+/-0.9 to 8.8+/-1.5 cm H(2)O at 1 min and then rapidly returned to the baseline within 2 min, when Ppv continued to increase and reached the peak of 36+/-7 cm H(2)O at 3.5 min after antigen. This greater increase in Ppv-to-P micro hv gradient than that in P micro hv-to-Pcv gradient after antigen indicated that the constriction of the portal veins and the sinusoids much predominates over that of the hepatic veins. Along with this hepatic pre- and sinusoidal constriction, the liver lobe thickness significantly decreased by 4% after antigen.


CONCLUSIONS
Pre-sinusoidal constriction during anaphylactic shock in anaesthetized rats increased the portal venous pressure while the hepatic venular pressure only increased slightly and transiently. This predominant pre-sinusoidal constriction is accompanied by a decrease in liver volume.
Takano
Hiromichi
H
Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan.
Shibamoto
Toshishige
T
Zhang
Wei
W
Kurata
Yasutaka
Y
Toga
Hirohisa
H
D000707:Anaphylaxis / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology*; D000758:Anesthesia; D000818:Animals; D000941:Antigens / Q000009:adverse effects / Q000276:immunology; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000187:drug effects; D006503:Hepatic Veins / Q000187:drug effects / Q000276:immunology; D007022:Hypotension / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology*; D008099:Liver / Q000098:blood supply* / Q000187:drug effects / Q000276:immunology; D008102:Liver Circulation / Q000187:drug effects / Q000276:immunology; D008297:Male; D009929:Organ Size / Q000187:drug effects / Q000276:immunology; D010047:Ovalbumin / Q000276:immunology / Q000494:pharmacology; D017082:Portal Pressure / Q000187:drug effects; D011169:Portal Vein / Q000187:drug effects / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects / Q000276:immunology; D014680:Veins / Q000187:drug effects / Q000276:immunology; D014690:Venous Pressure / Q000187:drug effects
D000941:Antigens; D010047:Ovalbumin