Characteristics of Ba2+-stimulated insulin release with special reference to pancreatic beta-cells sensitized by cyclic AMP.
Ca2+-dependent processes are activated by Ba2+ in a variety of biological systems. When Ca2+ was replaced by equimolar amounts of Ba2+ there was a marked increase in insulin secretion from beta-cell-rich pancreatic islets microdissected from ob/ob-mice. At both 3 and 20 mM glucose Ba2+ stimulated insulin release in a concentration-dependent manner, being less stimulatory at high concentrations. The stimulatory effect of Ba2+ on insulin release is similar to that of Ca2+ in being more pronounced and reached at lower concentrations when the beta-cells were sensitized by cyclic AMP. However, both glucose oxidation and utilization were suppressed when Ca2+ was replaced by equimolar amounts of Ba2+. Ba2+-stimulated insulin release resembled physiological secretion initiated by Ca2+ in being inhibited by L-epinephrine, pentobarbital and a low oxygen tension.
D000818:Animals; D001464:Barium / Q000494:pharmacology*; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese
D007328:Insulin; D001464:Barium; D003994:Bucladesine; D000242:Cyclic AMP; D005947:Glucose; D002118:Calcium