Abstract
The effect of hepatic blood flow and portal insulin concentration on insulin extraction
during one passage through the isolated perfused rat liver was studied. The percentage
of insulin extracted was constant over the physiological range of blood flows (4 to
28 ml/min). The total amount of insulin extracted increased as the input concentration
was raised from 48 to 4860 µU/ml with the highest level of extraction being approximately
700 µU of insulin per gram of liver per minute. When square wave input pulses of 243
to 4860 µU/ml were presented, about 5% of this insulin was retained and then released
by the liver for periods up to 15 minutes after the cessation of the input. The possible
roles of glucose and glucagon as regulators of insulin extraction were studied. Glucose
(300 mg/dl), as compared with no glucose, led to a significant reduction of insulin
extraction (22% vs. 38%, p < 0.001). Glucagon had no effect on insulin extraction
in the presence of constant levels of glucose. It is concluded, therefore, that glucose
may increase circulating insulin levels not only by its well known stimulation of
insulin secretion by the pancreas, but also by inhibiting insulin extraction by the
liver.
Key words
Insulin Extraction - Insulin Levels - Glucose Glucagon
1 Supported by Grant BMS 75-04049 from the National Science Foundation. Portions of
this paper have been published in abstract form (Honey and Price, 1977).
2 Supported by Research Development Award DE-12433 from the National Institute of Dental
Research, National Institutes of Health.
