The endocrine pancreas

Within the islets, distinct cell types can be distinguished. The principal types are A cells, B cells. 

---

High amounts of somatostatin are found in the CNS, the peripheral nervous system, the gut and the endocrine pancreas whereas the kidneys, adrenals, thyroid, submandibular glands, prostate and placenta produce rather low amounts. In particular, the hypothalamus, all limbic structures, the deeper layers of the cerebral cortex, the striatum, the periaqueductal central grey and all levels of the major sensoty pathway are brain areas that are especially rich in somatostatin. Eighty percent of the somatostatin immunoreactivity in the hypothalamus is found in cells of the anterior periventricular nucleus (Fig. 1, [1]). The gut 5 cells of the mucosa and neurons, which are intrinsic to the submucous and... 

Figure 3.20 A plot of the percentage of maximal activity of glucokinase and hexokinase against the glucose concentration. Hexokinase is present in most if not all cells. Glucokinase is only present in hepatocytes and p-cells of the Islets of Langerhans in the pancreas (known as the endocrine pancreas). The enzyme is physiologically very important in both tissues e.g. a low activity in the p-cells can be a cause of one type of diabetes mellitus.

Glutamine, along with glucose, can stimulate insulin secretion by the endocrine pancreas. The significance of this is the regulation of the plasma glutamine concentration is not known. 

The endocrine pancreas responds to this by altering its hormone release—there is an increase in insulin secretion and a reduction in glucagon secretion. The increase in the insu-lin/glucagon quotient and the availability of substrates trigger an anabolic phase in the tissues—particularly liver, muscle, and adipose tissues. 

Davis SN. Insulin, oral hypoglycemic agents, and the pharmacology of the endocrine pancreas. In Brunton LL, et Al, eds. The Pharmacohgical Basis of Therapeutics. 11th ed. New York McGraw-Hill 2006. 

Peavey DE. The endocrine pancreas. In Rhoades RA, Tanner GA, eds. Medical Physiology. 2nd ed. Philadelphia Lippincott Williams and Wilkins 2003. 

With this assay, basal insulin values of 5-15 pU/mL (30-90 pmol/L) are found in normal humans, with a peak rise to 60-90 U/mL (360-540 pmol/L) during meals. Similar assays for measuring all of the known hormones of the endocrine pancreas (including C-peptide and proinsulin) have been developed. 

Insulin is secreted by the beta cells of the endocrine pancreas, and is responsible for the regulation of glucose utilization. Insulin deficiency is responsible for some forms of diabetes, where it is used in replacement therapy (Kahn and Shechter, 1990). 

Bonner-Weir, S. (1991). Anatomy of the islet of Langerhans in the endocrine pancreas. In The Endocrine Pancreas (E. Samols, ed.), pp. 15-27. Raven Press, New York. 

The endocrine pancreas is pivotal in metabolic homeostasis and an integral component of metabolic regulation (see also Chapter 30). It is composed of 1-2 million islets of Langerhans scattered throughout the organ and forming... 

The pancreas possesses both endocrine and exocrine fnnctions. The islets of Langerhans, which contain the cells of the endocrine pancreas, secrete insnlin, glncagon, somatostatin, and other polypeptide hormones. The exocrine pancreas is composed of acini that secrete about 1 to 2 L/day of isotonic fluid that contains water, electrolytes, and pancreatic enzymes necessary for digestion. Bicarbonate is secreted primarily by the centroacinar (ductular) cells, and is the principal ion of physiologic importance. Pancreatic juice is delivered to the duodenum via the pancreatic ducts (Fig. 39-1) where the alkaline secretion (pH about 8.3) neutralizes gastric acid and provides an appropriate pH for maintaining the activity of pancreatic enzymes."... 

Mandarino L, Bonadonna R, McGuinness O, Wasserman D. Regulation of muscle glucose uptake in vivo. In Jefferson LS, Cherrington AD, eds. Handbook of Physiology, Section 7, The Endocrine System, Vol. 11, The Endocrine Pancreas and Regulation of Metabolism. Oxford, Oxford University Press, 2001 803-848. 

Lafferty KJ (1988) In van Schilfgarde R, Hardy MA (eds) Transplantation of the endocrine pancreas in diabetes mellitus. Elsevier, Amsterdam, p 279... 

Rajotte RV, Warnock GL, Coulombe MG (1988) In Transplantation of the Endocrine Pancreas in Diabetes Millitus, van Schilfgarde R, Hardy MA, (eds) Elsevier 125-135... 

INSULIN, ORAL HYPOGLYCEMIC AGENTS, AND THE PHARMACOLOGY OF THE ENDOCRINE PANCREAS... 

CHAPTER 60 Insulin, Oral Hypoglycemic Agents, and the Pharmacology of the Endocrine Pancreas 1039... 

---