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. 2004 May 24;101(22):8313–8318. doi: 10.1073/pnas.0306709101

Fig. 2.

Fig. 2.

Blood glucose and insulin responses in vivo and insulin secretion in vitro. (a) Blood glucose levels (Left) and serum insulin levels (Right) after glucose load under normal conditions. There are no statistical differences in blood glucose and serum insulin levels between Noc2+/+ mice and Noc2-/- mice. (b) Blood glucose levels (Left) and serum insulin levels (Right) after glucose load under water immersion stress. Blood glucose levels at 90, 120, and 180 min after glucose load are significantly higher in Noc2-/- mice than in Noc2+/+ mice (n = 13 at each time point; *, P < 0.01 at 90 min; **, P < 0.001 at 120 and 180 min). Serum insulin levels at 30 min after glucose load are significantly lower in Noc2-/- mice than in Noc2+/+ mice (Noc2+/+ mice: 919.5 ± 123.8 pg/ml, n = 22; Noc2-/- mice: 451.7 ± 101.9 pg/ml, n = 22, *, P < 0.001). (c) Insulin secretion from isolated pancreatic islets. There is no difference in insulin secretion at 2.8 mM glucose (basal state). Glucose (16.7 mM)-stimulated insulin secretion in Noc2-/- mice is significantly lower than in Noc2+/+ mice (Noc2+/+ mice: 1.82 ± 0.21 ng per islet per 30 min n = 16; Noc2-/- mice: 1.06 ± 0.11 ng per islet for 30 min, n = 15). High K+ (60 mM)-stimulated insulin secretion of Noc2-/- mice is also significantly lower than in Noc2+/+ mice (Noc2+/+ mice: 1.43 ± 0.16 ng per islet for 30 min; Noc2-/- mice: 0.83 ± 0.10 ng per islet per 30 min, n = 12). However, there is no significant difference in high K+-stimulated insulin secretion between Noc2+/+ mice and Noc2-/- mice when pancreatic islets are treated with PTX (30 ng/ml, 48 h) after isolation. Open circles and columns, Noc2+/+ mice; filled circles and columns, Noc2-/- mice. Values are means ± SEM. *, P < 0.005; **, P < 0.001. (d) Inhibition of insulin secretion by clonidine. Results are expressed as means ± SEM of percent insulin secretion relative to that in the absence of clonidine. The inhibitory effect of clonidine on insulin secretion is significantly greater in Noc2-/- mice than in Noc2+/+ mice at all concentrations examined. *, P < 0.005; **, P < 0.0005.