In vivo modulation of gap junctions and dye coupling between B-cells of the intact pancreatic islet

Diabetes. 1983 Sep;32(9):858-68. doi: 10.2337/diab.32.9.858.

Abstract

The extent of gap junctions and dye coupling between insulin-producing B-cells was analyzed on islets of Langerhans isolated from adult rats treated for one day with glibenclamide, an insulin secretagogue, or diazoxide, a blocker of insulin release, or a combination of the two drugs. Glibenclamide treatment was associated with a marked depletion of the islet insulin content, an effect which was blocked by pretreatment of the rats with diazoxide. Diazoxide alone caused a marked increase in the plasma glucose level, and a decrease in the level of circulating insulin and in the hormone content of the B-cells. Quantitative analysis showed that (1) under control conditions, B-cells are connected by minute gap junctions (as evaluated on freeze-fracture replicas) and show a nonuniform and apparently restricted dye coupling (as determined by microinjection of the low-molecular-weight fluorescent probe Lucifer Yellow CH); (2) each of the three treatments tested significantly increased the relative and absolute gap junction area of the B-cells and the number of detectable, dye coupled B-cells per microinjection. After treatment with glibenclamide alone or with diazoxide plus glibenclamide, a 1.5-1.8-fold increase in gap junction area and a 2.7-3.7-fold increase in the number of dye-coupled B-cells were observed. In contrast, following treatment with diazoxide alone, gap junctions and dye coupling were found increased 1.8 and 8.7 times, respectively, as compared with control values.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blood Glucose / analysis
  • Cell Communication / drug effects
  • Cytoplasmic Granules / ultrastructure
  • Diazoxide / pharmacology
  • Freeze Fracturing
  • Glyburide / pharmacology
  • Insulin / blood
  • Intercellular Junctions / ultrastructure*
  • Islets of Langerhans / ultrastructure*
  • Male
  • Rats

Substances

  • Blood Glucose
  • Insulin
  • Diazoxide
  • Glyburide