Tags

Type your tag names separated by a space and hit enter

Fast reversibility of glucose-induced desensitization in rat pancreatic islets. Evidence for an involvement of ionic fluxes.
Diabetes. 1996 Apr; 45(4):502-6.D

Abstract

The present study was done to achieve a better understanding of the role of ionic flux alterations in glucose-induced desensitization of pancreatic beta-cells. Moreover, we investigated the reversibility of glucose-induced desensitization after different times of exposure to high glucose to ascertain the time necessary for desensitization reversal and to determine whether it depends on the length of high glucose exposure. Glucose desensitization was obtained by incubating rat pancreatic islets for 6 h in CMRL medium containing 16.7 mmol/l glucose. At the end of this period, insulin release, 86Rb efflux, and 45Ca uptake were measured in parallel experiments. In islets cultured at 16.7 mmol/l glucose, maximal glucose-induced insulin release was reduced (848 +/- 97 pg x islet-1 x 30 min-1) in comparison to islets incubated at 5.5 mmol/l glucose (1,436 +/- 144, n = 7, P < 0.01). In contrast, insulin content was similar in the two groups, being 41.0 +/- 2.7 and 47.8 +/- 2.2 ng/islet in islets exposed to 16.7 or 5.5 mmol/l glucose, respectively (P = 0.167). The effect of glucose on both 86Rb efflux and 45Ca uptake was also significantly reduced in 16.7 mmol/l glucose-cultured islets. 86Rb efflux was inhibited only 19 +/- 4% in islets cultured at high glucose with respect to 56 +/- 7% in control islets (n = 5, P < 0.001). 45Ca uptake was 10.5 +/- 1.7 pmol/islet (mean +/- SE, n = 9) in islets cultured at high glucose with respect to 19.7 +/- 2.4 pmol/islet in control islets (P < 0.001). In contrast, the effect of glyburide (10 micromol/l) on insulin release, 86Rb efflux, and 45Ca uptake was similar in islets exposed to 5.5 or 16.7 mmol/l glucose. All the abnormalities observed in islets cultured at 16.7 mmol/l glucose were promptly and simultaneously reversible after islets were transferred in culture medium at 5.5 mmol/l glucose; both insulin secretion and glucose effects on 86Rb efflux and 45Ca uptake returned to values similar to control islets within 5 min. Also, islets exposed to high glucose for a longer period (24 h) recovered from both secretory and ionic abnormalities after 5 min of incubation in CMRL medium at 5.5 mmol/l glucose. Reversal from glucose desensitization was slower (45 - 60 min) when islets were incubated at 5.5 mmol/l glucose in Krebs-Ringer HEPES buffer instead of CMRL medium. The present data suggest that ion flux and consequent membrane-potential changes play a key role in the mechanism leading to glucose-induced desensitization of pancreatic beta-cells. Because a normal response to glyburide was observed in islets exposed to high glucose, a proximal signal defect for closure of K+ channels rather than an intrinsic defect in the channel is likely.

Authors+Show Affiliations

Institute of Internal Medicine, Endocrinology and Metabolism, University of Catania, Italy.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

8603773

Citation

Anello, M, et al. "Fast Reversibility of Glucose-induced Desensitization in Rat Pancreatic Islets. Evidence for an Involvement of Ionic Fluxes." Diabetes, vol. 45, no. 4, 1996, pp. 502-6.
Anello M, Rabuazzo AM, Degano C, et al. Fast reversibility of glucose-induced desensitization in rat pancreatic islets. Evidence for an involvement of ionic fluxes. Diabetes. 1996;45(4):502-6.
Anello, M., Rabuazzo, A. M., Degano, C., Caltabiano, V., Patanè, G., Vigneri, R., & Purrello, F. (1996). Fast reversibility of glucose-induced desensitization in rat pancreatic islets. Evidence for an involvement of ionic fluxes. Diabetes, 45(4), 502-6.
Anello M, et al. Fast Reversibility of Glucose-induced Desensitization in Rat Pancreatic Islets. Evidence for an Involvement of Ionic Fluxes. Diabetes. 1996;45(4):502-6. PubMed PMID: 8603773.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fast reversibility of glucose-induced desensitization in rat pancreatic islets. Evidence for an involvement of ionic fluxes. AU - Anello,M, AU - Rabuazzo,A M, AU - Degano,C, AU - Caltabiano,V, AU - Patanè,G, AU - Vigneri,R, AU - Purrello,F, PY - 1996/4/1/pubmed PY - 1996/4/1/medline PY - 1996/4/1/entrez SP - 502 EP - 6 JF - Diabetes JO - Diabetes VL - 45 IS - 4 N2 - The present study was done to achieve a better understanding of the role of ionic flux alterations in glucose-induced desensitization of pancreatic beta-cells. Moreover, we investigated the reversibility of glucose-induced desensitization after different times of exposure to high glucose to ascertain the time necessary for desensitization reversal and to determine whether it depends on the length of high glucose exposure. Glucose desensitization was obtained by incubating rat pancreatic islets for 6 h in CMRL medium containing 16.7 mmol/l glucose. At the end of this period, insulin release, 86Rb efflux, and 45Ca uptake were measured in parallel experiments. In islets cultured at 16.7 mmol/l glucose, maximal glucose-induced insulin release was reduced (848 +/- 97 pg x islet-1 x 30 min-1) in comparison to islets incubated at 5.5 mmol/l glucose (1,436 +/- 144, n = 7, P < 0.01). In contrast, insulin content was similar in the two groups, being 41.0 +/- 2.7 and 47.8 +/- 2.2 ng/islet in islets exposed to 16.7 or 5.5 mmol/l glucose, respectively (P = 0.167). The effect of glucose on both 86Rb efflux and 45Ca uptake was also significantly reduced in 16.7 mmol/l glucose-cultured islets. 86Rb efflux was inhibited only 19 +/- 4% in islets cultured at high glucose with respect to 56 +/- 7% in control islets (n = 5, P < 0.001). 45Ca uptake was 10.5 +/- 1.7 pmol/islet (mean +/- SE, n = 9) in islets cultured at high glucose with respect to 19.7 +/- 2.4 pmol/islet in control islets (P < 0.001). In contrast, the effect of glyburide (10 micromol/l) on insulin release, 86Rb efflux, and 45Ca uptake was similar in islets exposed to 5.5 or 16.7 mmol/l glucose. All the abnormalities observed in islets cultured at 16.7 mmol/l glucose were promptly and simultaneously reversible after islets were transferred in culture medium at 5.5 mmol/l glucose; both insulin secretion and glucose effects on 86Rb efflux and 45Ca uptake returned to values similar to control islets within 5 min. Also, islets exposed to high glucose for a longer period (24 h) recovered from both secretory and ionic abnormalities after 5 min of incubation in CMRL medium at 5.5 mmol/l glucose. Reversal from glucose desensitization was slower (45 - 60 min) when islets were incubated at 5.5 mmol/l glucose in Krebs-Ringer HEPES buffer instead of CMRL medium. The present data suggest that ion flux and consequent membrane-potential changes play a key role in the mechanism leading to glucose-induced desensitization of pancreatic beta-cells. Because a normal response to glyburide was observed in islets exposed to high glucose, a proximal signal defect for closure of K+ channels rather than an intrinsic defect in the channel is likely. SN - 0012-1797 UR - https://www.unboundmedicine.com/medline/citation/8603773/Fast_reversibility_of_glucose_induced_desensitization_in_rat_pancreatic_islets__Evidence_for_an_involvement_of_ionic_fluxes_ L2 - https://diabetes.diabetesjournals.org/lookup/pmidlookup?view=long&amp;pmid=8603773 DB - PRIME DP - Unbound Medicine ER -