The biological activity of catfish pancreatic somatostatin |
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Authors: | Hideki Oyama Jeanne Martin Karl Sussman Gordon C. Weir Alan Permutt |
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Affiliation: | 1. Department of Medicine, Metabolism Division, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO 63110, USA;2. Department of Pharmacology, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO 63110, USA;3. Department of Medicine, University of Colorado Medical School, Medical Service, VA Medical Center, 1055 Clermont Street, Denver, CO 80220, USA;4. Department of Medicine, Medical College of Virginia, Health Sciences Center, Box 876, Richmond, VA 23298, U.S.A. |
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Abstract: | Catfish pancreatic somatostatin, which contains eight additional amino acids on the amino terminus of a tetradecapeptide with considerable homology to tetradecapeptide somatostatin (SRIF), is a naturally occurring homology of the hypothalamic peptide. The purpose of these studies was to determibe the biological activity of this somatostatin homolog. Inhibition of 125I-labelled tyr1-SRIF binding to bovine pituitart plasma membranes by catfish pancreatic somatostatin was approximately 33% that of SRIF. Pancreatic somatostatin has full biological activity measured by inhibition of growth hormone release from isolated rat pituitary cells, but 0.01–0.1% the potency of SRIF. Pancreatic somatostatin at 100 ng/ml produced a 50–60% inhibition of insulin and glucagon secretion from perfused rat pancreas, while SRIF produced comparable inhibition at 10 ng/ml. This report demonstrates that a larger molecular form and natural homolog of SRIF, isolated from fish pancreas, has the same (but reduced) biological activities in rat assay systems as somatostatin originally isolated from sheep hypothalamus. |
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Keywords: | receptor binding growth hormone insulin and glucagon secretion |
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