Thromboxane A2 analogue contracts predominantly the hepatic veins in isolated canine liver.

Abstract

Thromboxane A2 (TxA2) is a potent vasoconstrictor and has been implicated as a mediator of liver diseases such as ischemic-reperfusion injury. We determined the effects of TxA2 and the well-known hepatic venoconstrictor histamine, on the vascular resistance distribution and liver weight in isolated canine livers perfused with blood via the portal vein. The stable TxA2 (STA2; 20 micrograms, n = 5) and histamine (5 micrograms, n = 6) similarly increased the hepatic total vascular resistance, 2.5- and 2.4-fold, respectively. The increase in the hepatic venous resistance was significantly greater than that of the portal resistance (threefold vs. 1.9-fold for STA2; threefold vs. 1.8-fold for histamine). Predominant hepatic venoconstriction induced by both agents was confirmed in livers perfused in a reverse direction from the hepatic vein to the portal vein, as shown by marked precapillary vasoconstriction. STA2 transiently increased liver weight loss (-3.6 g/100 g liver weight), followed by a gradual weight gain (9.0 g/100 g). Histamine caused a progressive weight gain (9.1 g/100 g). In conclusion, similar to histamine, TxA2 constricts predominantly the hepatic vein in isolated canine livers.

• Authors: H Urayama, T Shibamoto, H G Wang, S Koyama
• Journal: Prostaglandins (Prostaglandins) Vol. 52 Issue 6 Pg. 483-95 (Dec 1996) ISSN: 0090-6980 [Print] United States
• PMID: 8979308 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Vasoconstrictor Agents
• Thromboxane A2
• STA 2
• Histamine

Topics

• Animals
• Dogs
• Dose-Response Relationship, Drug
• Hemodynamics (drug effects)
• Hepatic Veins (drug effects)
• Histamine (pharmacology)
• In Vitro Techniques
• Liver (blood supply, drug effects)
• Organ Size (drug effects)
• Perfusion (methods)
• Thromboxane A2 (analogs & derivatives, pharmacology)
• Vascular Resistance (drug effects)
• Vasoconstriction (drug effects)
• Vasoconstrictor Agents (pharmacology)