Summary
Changes in glucose metabolism mediated by natural somatostatin and two derivatives
(octreotide, 008) were studied in hypoxic ischemic cell injury of the isolated perfused
rat liver. The tested somatostatin and its analogues were previously shown to exert
protective actions in liver damage induced by hypoxic ischemia and reperfusion. In
isolated perfused livers of rats starved for 24 hours and unstarved rats flow rate
was reduced and oxygen supply interrupted for 180 min. Then the livers were normoxically
reperfused for 30 min. Glucose and lactate concentration, as well as LDH and GLDH
activity, were determined in the effluent. In starved and unstarved rat livers hypoxic
ischemia resulted in a substantial enzyme release. In livers harvested from unstarved
rats hepatic glucose release was noticed which ceased towards prolonged low flow ischemia.
In livers harvested from starved rats containing low hepatic glycogen concentration
only minimal hepatic glucose release was present. In starved and unstarved rats pretreatment
with somatostatin, octreotide, and 008 significantly reduced LDH and GLDH release
(p<0.001). In unstarved rats natural somatostatin and octreotide pretreatment resulted
in a substantial output of glucose during the hypoxic ischemic perfusion period (p<0.001),
whereas livers with 008 pretreatment did not show any difference in glucose release
compared to controls. In livers harvested from starved rats neither somatostatin nor
octreotide nor 008 pretreatment led to a difference in glucose output observed in
controls. Natural somatostatin and octreotide cause a strong hepatic glucose release
even under hypoxic ischemic conditions in rat livers with filled glycogen stores.
The protective action of natural somatostatin, octreotide, and 008 is not mediated
by changes in glucose metabolism, and is not related to endocrine activity.
Key words
Liver Perfusion - Hypoxic Ischemia - Glucose Metabolism - Cell Death - Cytoprotection
