AJP - Endocrinology and Metabolism, Vol 253, Issue 4 E435-E442, Copyright © 1987 by American Physiological Society
Effect of somatostatin on glucose homeostasis in conscious long-fasted dogs
R. W. Stevenson, K. E. Steiner, G. K. Hendrick and A. D. Cherrington
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
The effects of somatostatin plus intraportal insulin and glucagon
replacement (pancreatic clamp) on carbohydrate metabolism were studied in
conscious dogs fasted for 7 days so that gluconeogenesis was a major
contributor to total glucose production. By use of [3-3H]glucose, glucose
production (Ra) and utilization (Rd) and glucose clearance were assessed
before and after implementation of the pancreatic clamp. After an initial
control period, somatostatin (0.8 microgram . kg-1 . min-1) was infused
with intraportal replacement amounts of glucagon (0.42 ng . kg-1 . min-1)
and insulin. The insulin infusion rate was varied to maintain euglycemia
and then kept constant (68 +/- 16 microU . kg-1 . min-1) for 250 min.
Plasma glucagon was similar (84 +/- 14 and 89 +/- 19 pg/ml) before and
during somatostatin infusion, while plasma insulin was lower (9.3 +/- 0.9
and 6.6 +/- 0.5 microU/ml, P less than 0.05). Plasma glucose levels
remained similar (89 +/- 2 and 96 +/- 9 mg/dl), while Ra and Rd and the
ratio of glucose clearance to plasma insulin were significantly (P less
than 0.05) increased (from 2.18 +/- 0.12 to 3.21 +/- 0.35 and 2.30 +/- 0.09
to 3.26 +/- 0.38 mg . kg-1 . min-1, and 0.30 +/- 0.03 to 0.59 +/- 0.11,
respectively). Net hepatic lactate uptake and [14C]alanine plus
[14C]lactate conversion to [14C]glucose increased (P greater than 0.05)
(from 9.32 +/- 0.47 to 16.54 +/- 2.97 mumol . kg-1 . min-1 and 100 to 263
+/- 37%, respectively). In conclusion, somatostatin alters glucose
clearance in 7-day fasted dogs, resulting in changes in several indices of
carbohydrate metabolism.
