110
BRIAN POOLË
sponse to partial hepatectomy in the livers of tumor-bearing animals
(Paschkis et al, 1955) is probably another manifestation of the same effect.
The livers of the tumor-bearing animals are farther from their equilibrium
size after hepatectomy than are those of the controls.
Wrba et al. (1962) reported that serum from partially hepatectomized
rats, mice, or hamsters stimulates P
32 uptake in embryonic mouse and rat
liver in vitro. Previously, Akamatsu (1923) and Glinos and Gey (1952)
had demonstrated a stimulation of the growth of liver expiants treated
with serum from hepatectomized rats. Katsuta and Takaoka (1963) were
unable to find a similar effect on disaggregated liver cells in tissue culture.
D. The Importance of the Hepatic Blood Supply
The size of the liver is very much dependent on its blood supply. Partial
ligation of the portal vein to the liver remnant after partial hepatectomy
in dogs has been reported to reduce the rate of hypertrophy (Grindlay
and Bollman, 1952). There are conflicting reports on the effect of this
operation on rats (Becker, 1963; Stephenson, 1932). The constriction of
the vena cava in dogs has a smaller effect (Grindlay and Bollman, 1952).
It has been reported that an end-to-side portocaval shunt in rats causes an
elevated mitotic index in the liver, with no gross cellular damage (Rubin
et al., 1964). In dogs the operation is reported to cause the liver to shrink
to half size and loose its powers of restoration after partial hepatectomy
(Mann et al., 1941). End-to-side portocaval shunt at the time of partial
hepatectomy reduces, but does not abolish, the hypertrophic response
(Mann, 1940).
Experiments that differentially affect the blood supply to different parts
of the liver are more instructive. Ligation of a branch of the portal vein to
a single lobe results in atrophy of that lobe and compensatory hypertrophy
of the other lobes, but the atrophied lobe will still show a hypertrophy
after partial hepatectomy (Weinbren, 1955).
If the blood flow through the liver of the domestic fowl is increased by
ligation of the vena cava above the kidneys, which forces systemic blood
through a small branch vein into the portal system, the liver gets larger,
and its rate of hypertrophy following partial hepatectomy is increased
(Higgins et al, 1932).
Alston and Thompson (1963) have measured the change in pressure drop
across the liver before and after partial hepatectomy. They reported that
there is an increase of only 4 cm of saline, which subsides after 24 hr. It
seems clear that increased blood pressure and blood flow can modify equilibrium liver size, but that the change in blood flow after partial hepatectomy
is inadequate in itself to account for the tremendously increased growth
rate observed at that time.
BRIAN POOLË
sponse to partial hepatectomy in the livers of tumor-bearing animals
(Paschkis et al, 1955) is probably another manifestation of the same effect.
The livers of the tumor-bearing animals are farther from their equilibrium
size after hepatectomy than are those of the controls.
Wrba et al. (1962) reported that serum from partially hepatectomized
rats, mice, or hamsters stimulates P
32 uptake in embryonic mouse and rat
liver in vitro. Previously, Akamatsu (1923) and Glinos and Gey (1952)
had demonstrated a stimulation of the growth of liver expiants treated
with serum from hepatectomized rats. Katsuta and Takaoka (1963) were
unable to find a similar effect on disaggregated liver cells in tissue culture.
D. The Importance of the Hepatic Blood Supply
The size of the liver is very much dependent on its blood supply. Partial
ligation of the portal vein to the liver remnant after partial hepatectomy
in dogs has been reported to reduce the rate of hypertrophy (Grindlay
and Bollman, 1952). There are conflicting reports on the effect of this
operation on rats (Becker, 1963; Stephenson, 1932). The constriction of
the vena cava in dogs has a smaller effect (Grindlay and Bollman, 1952).
It has been reported that an end-to-side portocaval shunt in rats causes an
elevated mitotic index in the liver, with no gross cellular damage (Rubin
et al., 1964). In dogs the operation is reported to cause the liver to shrink
to half size and loose its powers of restoration after partial hepatectomy
(Mann et al., 1941). End-to-side portocaval shunt at the time of partial
hepatectomy reduces, but does not abolish, the hypertrophic response
(Mann, 1940).
Experiments that differentially affect the blood supply to different parts
of the liver are more instructive. Ligation of a branch of the portal vein to
a single lobe results in atrophy of that lobe and compensatory hypertrophy
of the other lobes, but the atrophied lobe will still show a hypertrophy
after partial hepatectomy (Weinbren, 1955).
If the blood flow through the liver of the domestic fowl is increased by
ligation of the vena cava above the kidneys, which forces systemic blood
through a small branch vein into the portal system, the liver gets larger,
and its rate of hypertrophy following partial hepatectomy is increased
(Higgins et al, 1932).
Alston and Thompson (1963) have measured the change in pressure drop
across the liver before and after partial hepatectomy. They reported that
there is an increase of only 4 cm of saline, which subsides after 24 hr. It
seems clear that increased blood pressure and blood flow can modify equilibrium liver size, but that the change in blood flow after partial hepatectomy
is inadequate in itself to account for the tremendously increased growth
rate observed at that time.