Glibenclamide stimulates and glucose inhibits glucagon release induced by calcium deprivation

Role of calcium in suppression of glucagon release from isolated diabetic rat pancreata.

“…Conversely, the presence of Ca2+, (2.1 mM) with 110 jeU/ml of insulin and 15 mM of glucose in the perfusate suppressed glucagon release. These results are in agreement with previous findings that Ca2+ deprivation (0.17-0.23 mM) with high concentrations of glucose in a medium, stimulated glucagon release in minced pieces of normal rat pancreas (Leclercq-Meyer et al 1973), perfused normal rat pancreas (Leclercq-Meyer et al 1975Grill et al 1984), perifused normal rat islets (Ashby and Speake 1975), and in monolayer islet cell cultures prepared from normal rat pancreas (Wollheim et al 1976). The present study suggests that Ca2+ is needed for the suppression of glucagon release in the presence of exogenous insulin and high concentrations of glucose, though the mechanism of the increase of glucagon release remains obscure.…”