Glucose and phosphate modulation of intracellular 45Ca incorporated into pancreatic islets during culture in the absence and presence of serum.
The effects of glucose and phosphate on the intracellular 45Ca content were measured in beta-cell-rich pancreatic islets cultured in media containing or lacking serum. Irrespective of the glucose and serum concentrations there were no or very small increments of 45Ca contents when phosphate was raised from 0.8 to 5.8 mM during culture for 1 day. However, after 7 days of culture in serum-free medium there was a massive accumulation of 45Ca in the islets in response to the higher phosphate concentration. Glucose markedly reduced, and serum eliminated, the extensive accumulation probably due to increased cell viability. In the cells cultured in the presence of serum, raising the glucose concentration from 1.0 to 5.5 mM resulted in an increased incorporation of 45Ca. This effect was particularly pronounced after culture for 7 days in 5.8 mM phosphate. A further increase of glucose to 20 mM reduced the 45Ca content. The results are consistent with the concept that glucose both stimulates 45Ca uptake into different beta-cell pools and degranulates the cell with associated loss of intracellular calcium from the granular calcium pool.
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media; D046508:Culture Techniques; D005947:Glucose / Q000502:physiology*; D007515:Islets of Langerhans / Q000378:metabolism*; D051379:Mice; D008820:Mice, Obese; D010710:Phosphates / Q000502:physiology*
D003470:Culture Media; D010710:Phosphates; D005947:Glucose; D002118:Calcium