FIGURE 6.

GX sPLA₂ deficiency enhances GSIS in vivo and protects mice from age-related glucose intolerance and beta-cell dysfunction. A, young (3-month-old) and (B) old (15-month-old) WT and GX KO mice were fasted for 6 h prior to intraperitoneal injection of 2 mg glucose/g bodyweight, and glucose concentrations were determined at the indicated time after injection (n = 4–5). Glucose values in 15-month-old WT mice measured 90 and 120 min after glucose injection exceeded the limit of the glucose meter (dotted line). C, Islets (25 islets per mouse) were isolated from 2- and 14-month-old WT and GX KO mice (n = 4–5), cultured overnight, washed, and equilibrated in assay buffer containing 5 mm glucose, incubated for 40 min in either 5 or 20 mm glucose as indicated. Insulin in the assay media was determined and normalized to total insulin in the corresponding islets. For both groups, values are expressed as percentage of total cellular insulin. Data are presented as mean ± S.E.; *, p < 0.05; **, p < 0.01.