Summary
In the present study, human islets were isolated by collagenase digestion from the pancreases of three kidney donors. Maintainance of the islets in tissue culture enabled insulin release, glucose oxidation and Ca2+-calmodulin-dependent protein phosphorylation to be determined using the same islets. Increasing glucose over a range 0–20 mmol/l resulted in a sigmoidal stimulation of insulin release (28.8±5.2 to 118.4±25.8 μU-islet−-h−, n=10; threshold <4 mmol/l). There was a marked correlation between the insulin secretory response of the islets to glucose and their rate of glucose oxidation (5.9±0.3 at glucose 2 mmol/l up to 25.8±1.8 pmol-islet−.h− at 20 mmol/l, r = 0.98). N-acetylglucosamine (20 mmol/l) failed to elicit a secretory response from the islets. Stimulation of insulin secretion by glucose was dependent upon the presence of extracellular Ca2+. Extracts of the islets contained a Ca2+-calmodulin-dependent protein kinase which phosphorylated a 48-kdalton endogenous polypeptide. Myosin light-chain kinase activity was demonstrated in the presence of exogenous myosin light chains. This report demonstrates for the first time the sigmoidal nature of glucose-stimulated insulin release from isolated human islets, and its correlation with enhanced glucose oxidation. Furthermore, this is the first report of the presence of Ca2+-dependent protein kinases in human islets.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Gray DWR, McShane P, Grant AM, Morris PJ (1984) A method for isolation of islets of Langerhans from the human pancreas. Diabetes 33: 1055–1061
Krebs HA, Henseleit K (1932) Untersuchungen über die Harnstoffbildung im Tierkörper. Hoppe-Seylers Z Physiol Chem 210: 33–63
Ashcroft SJH, Crossley JR (1975) Effects of glucose, N-acetylglucosamine, glyceraldehyde and other sugars on insulin release in vivo. Diabetologia 11: 274–279
Ashcroft SJH, Hedeskov CJ, Randle PJ (1970) Glucose metabolism in mouse pancreatic islets. Biochem J 118: 143–154
Laemmli, UK (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227: 680–685
Harrison DE, Ashcroft SJH (1982) Effects of Ca2+, calmodulin and cyclic AMP on the phosphorylation of endogenous proteins by homogenates of rat islets of Langerhans. Biochim Biophys Acta 714: 313–319
Sener A, Kawazu S, Hutton JC, Boschero AC, Devis G, Somers G, Herchueltz A, Malaisse WJ (1978) The stimulus-secretion coupling of glucose induced insulin release. Effect of exogenous pyruvate on islet function. Biochem J 176: 217–232
Grant AM, Christie MR, Ashcroft SJH (1980) Insulin release from human pancreatic islets in vitro. Diabetologia 19: 114–117
Ashcroft SJH, Bassett JM, Randle PJ (1971) Isolation of human pancreatic islets capable of releasing insulin and metabolizing glucose in vitro. Lancet 1: 888–889
Andersson A, Borg H, Groth C-G, Gunnarsson R, Hellerström C, Lundgren G, Westman J, Östman J (1976) Survival of isolated human islets of Langerhans maintained in tissue culture. J Clin Invest 57: 1295–1301
Lohmann D, Jahr H, Verlohren H-J, Schmidt S, Heilmann W, Zuhlke H, Hartig W, Mattig H (1980) Insulin secretion in maturity-onset diabetes. Function of isolated islets. Horm Metab Res 12: 349–353
Ashcroft SJH (1980) Glucoreceptor mechanisms and the control of insulin release and biosynthesis. Diabetologia 18: 5–15
Cahill GF, Herrera MG, Morgan AP, Soelder JS, Steinke J, Levy PL, Reichard GA, Kipnis DM (1966) Hormone-fuel interrelationships during fasting. J Clin Invest 45: 1751–1769
Williams IH, Ashcroft SJH (1978) N-acetylglucosamine and the substrate-site hypothesis for the control of insulin biosynthesis and secretion. FEBS Lett 87: 115–120
Wollheim CB, Sharp GWG (1981) Regulation of insulin release by calcium. Physiol Rev 61: 914–973
Sugden MC, Christie MR, Ashcroft SJH (1979) Presence and possible role of calcium-dependent regulator (calmodulin) in rat islets of Langerhans. FEBS Letts 105: 95–100
Gagliardino JJ, Harrison DE, Christie MR, Gagliardino EE, Ashcroft SJH (1980) Evidence for the participation of calmodulin in stimulus-secretion coupling in the pancreatic β-cell. Biochem J 192: 919–927
Schatzman RC, Wise BC, Kuo JF (1981) Phospholipid-sensitive calcium-dependent protein kinase: inhibition by antipsychotic drugs. Biochem Biophys Res Commun 98: 669–676
Lord JM, Ashcroft SJH (1984) Identification and characterization of Ca2+-phospholipid-dependent protein kinase in rat islets and hamster β-cells. Biochem J 219: 547–551
Harrison DE, Ashcroft SJH (1982) Phosphorylation-dephosphorylation mechanisms and insulin secretion: Ca2+-dependent enzymes of protein and phospholipid metabolism in rat islets of Langerhans. Diabetologia 23: 172–173
Penn EJ, Brocklehurst KW, Sopwith AM, Hales CN, Hutton JC (1982) Ca2+-calmodulin dependent myosin light chain phosphorylating activity in insulin-secreting tissues. FEBS Letts 139: 4–8
MacDonald MJ, Kowluru A (1982) Ca2+-calmodulin dependent myosin phosphorylation by pancreatic islets. Diabetes 31: 566–570
Grant AM (1984) Developmental, functional and immunological aspects of human islets of Langerhans. D. Phil. Thesis, University of Oxford
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Harrison, D.E., Christie, M.R. & Gray, D.W.R. Properties of isolated human islets of langerhans: insulin secretion, glucose oxidation and protein phosphorylation. Diabetologia 28, 99–103 (1985). https://doi.org/10.1007/BF00279924
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00279924