Dysregulation of calcium channels decreases parasecretion in pancreatic ß-cells in rats born small for gestational age.

ABSTRACT

OBJECTIVE: To investigate the role of intrauterine malnourishment in the development and function of pancreatic islet ß-cells. METHODS: Whole-cell patch clamping was used to record voltage-gated calcium channel (VGCC)-mediated currents. Insulin secretion was detected by measuring capacitance using a sequence of sine wave stimuli. VGCC currents and insulin secretion were measured in the small for gestational age (SGA) group treated with human recombinant growth hormone (hGH). RESULTS: The membrane capacitance in the SGA group (6.4 ± 0.9 fF/Pf) was significantly reduced. Calcium current density and peak current density in the SGA group were also markedly decreased, whereas other measurements of calcium channels were unaltered. Treatment with hGH significantly rescued the membrane capacitance, whereas calcium channels were not affected. CONCLUSION: Our data suggest that decreased ß-cell secretion is caused by a decreased expression of calcium channels and reduced calcium currents. hGH restores ß-cell secretion in SGA animals, possibly independently of VGCC.