Effects of splenectomy and splenic artery ligation on the portal pressure in portal hypertensive rats

Abstract

Immediate, short-, and long-term effects of splenectomy and splenic artery ligation on the portal pressure were studied in animal models experimentally created by partial portal vein ligation. The portal pressure of these animals would usually elevate immediately after partial ligation of the portal vein from a normal level of 6.0 ± 0.5 to 14.8 ± 1.3 mm Hg ( P < 0.005), which could be maintained at least for 6 months. The portal pressure measured at 2 weeks, 4 weeks, and 6 months after portal vein ligation was 14.0 ± 2.7, 15.2 ± 2.7, and 12.7 ± 2.0 mm Hg, respectively ( P < 0.005, as compared with the normal). When splenectomy was performed on these animals at 2 weeks after partial portal vein ligation, the pressure dropped immediately but only transiently from 14.0 ± 2.7 to 11.0 ± 3.0 mm Hg, and bounced back to the presplenectomy level in 20 sec. After an additional 2 weeks, the portal pressure in these splenectomized rats was usually at 15.2 ± 4.2 mm Hg, which was indistinguishable from that of rats whose portal vein was ligated but the spleen was not removed. Six months after splenectomy, however, the portal hypertensive rats had a portal pressure of 17.1 ± 6.4 mm Hg, which was significantly higher than that of the controls. Splenic artery ligation, on the other hand, did not result in any immediate decrease in portal pressure (14.0 ± 2.7 mm Hg vs 14.6 ± 1.4 mm Hg; P > 0.1). However, at 2 weeks, animals that had undergone splenic artery ligation had significantly lower portal pressure than the control animals (12.0 ± 1.9 mm Hg vs 15.4 ± 2.7 mm Hg; P < 0.05), and the difference in the pressure between these two groups became even more pronounced at 6 months (10.5 ± 2.6 mm Hg vs 15.4 ± 2.7 mm Hg; P < 0.05). We concluded that in the long-run splenectomy would not lower the portal pressure of portal hypertensive rats, while ligation of the splenic artery would.