A-C. Traces showing the responses of islets to the calcium channel blocker nifedipine after exposure to 15mM glucose for neonatal islets at postnatal day 0 (A, N=28), day 4 (B, N=32), and day 12 (C, N=28). Adult traces (dotted black lines, N=86) are used for comparison to the neonatal progression. D. Bar graph of the amplitude of response to stimulation. Asterisks (*) indicate differences between adult and neonatal [Ca2+]i traces based on N=3 trials for each neonatal day and N=9 for adult. **P<0.01, N.S. not significant.