AJP - Endocrinology and Metabolism, Vol 254, Issue 2 E214-E221, Copyright © 1988 by American Physiological Society
Hepatic extraction of somatostatin in conscious dogs
Z. Chap, T. Ishida, R. H. Jones, J. R. Pena, A. Vinik and J. B. Field
Diabetes Research Laboratory, Baylor College of Medicine, Houston, Texas 77225-0269.
Fractional hepatic extraction of endogenous somatostatin immunoreactivity
was examined in conscious dogs with Doppler flow probes on the portal vein
and hepatic artery and catheters in the portal and hepatic veins and
carotid artery before and after induction of hypoglycemia by infusion of
insulin. Insulin infusion (1 and 2 mU.kg-1.min-1) decreased arterial plasma
glucose from 76 +/- 4 mg/dl to a nadir of 41 +/- 2 mg/dl. Basal portal vein
somatostatin was 117 +/- 11 pg/ml, which was significantly greater than the
97 +/- 12 pg/ml in the hepatic vein (P less than 0.05) and 79 +/- 8 pg/ml
in the carotid artery (P less than 0.05). Hypoglycemia significantly
augmented portal vein somatostatin to 206 +/- 32 pg/ml with parallel
increases in the hepatic vein and carotid artery. The mean basal fractional
hepatic extraction of total somatostatin immunoreactivity was 9 +/- 6% and
was unchanged during hypoglycemia (14 +/- 4%). Column chromatography of the
portal vein somatostatin immunoreactivity in the basal period yielded three
peaks with most of the material eluting with somatostatin-14 and the void
volume. Very little somatostatin-28 was detected. There was very little
hepatic extraction of the void volume material while approximately 50% of
somatostatin-14 was removed by that organ. After insulin-induced
hypoglycemia, there was the greatest percent increase in somatostatin-28
and a doubling of somatostatin-14 and the void volume material. Most of the
somatostatins-14 and -28 were removed by the liver, while extraction of the
void volume material was negligible.(ABSTRACT TRUNCATED AT 250 WORDS)
