Obstruction of ductus venosus stimulates cell proliferation in organs of fetal sheep

In growth restricted fetuses, hepatic blood flow is reduced. This suggests the hypothesis that liver blood flow. controls fetal growth. In 11 near term sheep the ductus venosus was blocked with an embolization coil in one fetus (experimental) and left patent in the twin (control). Arterial catheters were placed in both fetuses. After termination [mean (s.d.) 5 days (2) after surgery] the fetal body and organs were weighed. The cell proliferation rate (pKi-67) was determined in tissue samples of the liver, heart, skeletal muscle, kidneys and placenta (n = 6). Blood flow through the umbilical vein measured by Doppler ultrasound did not differ in control and experimental fetuses [experimental: 600 (101) ml/min; control: 626 (89) ml/min]. In experimental fetuses, blood flow through the ductus venosus was negligible (colour Doppler), and thus hepatic blood flow was increased. Absolute and relative (percentage of body weight) liver weights were increased in experimental fetuses [liver weight: 119 (34)g versus 84 (17) g; relative liver weight: 4.3 (0.8) per cent versus 3.4 (0.8) per cent; P = 0.002, n = 11]. The cell proliferation rate was increased significantly (twofold) in heart muscle, skeletal muscle and kidneys, and sixfold in liver. It is concluded that increases of hepatic blood flow stimulate cell proliferation in major organs of the ovine fetus. (C) 2001 Harcourt Publishers Ltd.