title: Effect of training on insulin secretion from single pancreatic beta cells.
abstract: The objective of this study was to determine whether insulin secretion from single pancreatic beta cells is reduced by endurance training. Male Sprague Dawley rats either trained (T, N = 9) for 11 wk on a rodent treadmill, remained sedentary, and were fed ad libitum (S, N = 8) or remained sedentary and were food restricted (pair fed, PF, N = 8) so that final body weights were similar to T. After training, T had significantly higher red gastrocnemius muscle citrate synthase activity compared with S and PF. In vivo insulin secretion was lower in T (4.6 +/- 1.4 ng.ml-1, mean +/- SEM of 70' + 90' concentrations during a hyperglycemic glucose clamp) when compared with S, 8.1 +/- 1.6 and PF, 9.7 +/- 1.7 ng.ml-1. In vitro insulin secretion from single beta cells was measured using the cell blot assay (Kendall and Hymer, Endocrinology, 121:2260-2262, 1987) and T, had lower secretion 2.6 +/- 1.4 pg.cell-1 when compared (P less than 0.05) with S, 6.7 +/- 0.6, but not lower than PF, 4.1 +/- 1.7 pg.cell-1. These data suggest that some of the training-induced reduction in insulin secretory response to glucose may be attributable to changes within the beta cell itself.
authors.affiliation: Laboratory for Human Performance Research, Pennsylvania State University, University Park 16802.
authors.forename: P A
authors.initials: PA
authors.lastname: Farrell
authors.forename: A L
authors.initials: AL
authors.lastname: Caston
authors.forename: D
authors.initials: D
authors.lastname: Rodd
authors.forename: J
authors.initials: J
authors.lastname: Engdahl
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D002469:Cell Separation; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology* / Q000378:metabolism; D008297:Male; D010805:Physical Conditioning, Animal; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007328:Insulin