Endocrinology
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Islet isografts were injected into the portal veins of rats made diabetic with streptozotocin. The isografts normalized not only plasma glucose and insulin levels but also the elevated plasma immunoreactive glucagon level. ⋯ In vitro glucagon secretion to an arginine stimulus could not be demonstrated, although it would have been expected demonstrated, although it would have been expected in normal islets. Thus, it appears that insulin derived from transplanted islets is capable of correcting endogenous hyperglucagonemia and of ameliorating the effects of experimental diabetes while transplanted islet glucagon secretion is relatively suppressed.
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Perfusion of growth hormone inhibitory factor (somatostatin) into rat pancreas inhibited secretion of glucagon and insulin into medium containing 5.5 mM glucose. A 15-min infusion of arginine (20 mM) greatly increased glucagon and insulin secretion. When perfused simultaneously with arginine, somatostatin (55 nM) abolished the increase in glucagon secretion. ⋯ These results demonstrate a direct effect of somatostatin on the pancreas to inhibit secretion of glucagon and insulin. The failure of somatostatin to inhibit insulin secretion in pancreatic islets may be due to alterations in the beta cells produced by the isolation procedure. It is also possible that the effect of somatostatin on insulin secretion may be mediated indirectly.
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Biography Historical Article
Presidential address: response to the presentation of the presidential plaque.