Effect of Glucose and K⁺ Depolarization on Cytosolic Free Ca²⁺ in Cultured Neonatal Islets

Summary

In cultured neonatal islet cells, glucose (16.7 mM) and K⁺ (50 mM) increased cytosolic free Ca²⁺ ([Ca²⁺]i). The increments in [Ca²⁺]i induced by either glucose or K⁺ were similar to those obtained in cultured adultislet cells but only half of that recorded in freshly isolated adult islet cells. These data indicate that, in neonatal islet cells, the reduced insulin release in response to glucose is associated with a diminished increase in [Ca²⁺]i. This reduced insulin response may not solely be due to an impaired regulation of the ATP-sensitive K⁺ channels as previously suggested. It may also result from some alteration in the process of Ca²⁺ inflow through voltage-sensitive Ca²⁺ channels.

Key words

Pancreatic B Cell - Insulin Release - Neonatal Islets - Ca²⁺ Channels - Cytosolic Free Ca²⁺