Extracellular Ca2+-dependent cAMP production. Extracellular Ca2+-dependent cAMP production. Islets were incubated in KRBH buffer containing 2.8 mmol/l glucose for 1 h. Then, the Ca2+-free islets were washed three times in Ca2+-free KRBH buffer containing 100 μmol/l EGTA. cAMP production was determined after a 20-min incubation in Ca2+-containing (+) or Ca2+-free (-) buffer, as indicated, in absence (C) (□)or presence of PDBu (1 μmol/l) ([cjs2090]), CCh (200 μmol/l) ([cjs2108]), or CCK (400 nmol/l) ([cjs2089]). Values are means ± SE for the number of independent experiments shown at the base of each bar; Ca2+-depleted C, n = 7. *P < 0.001 vs. Ca2+-containing C; ψ P < 0.01 vs. Ca2+-depleted C; and other P values were determined by one-way ANOVA and multiple-comparison test. Yingrao Tian, and Suzanne G. Laychock Diabetes 2001;50:2505-2513 ©2001 by American Diabetes Association