Disturbances in glucose-tolerance, insulin-release, and stress-induced hyperglycemia upon disruption of the CaV2.3 (α1E) subunit of voltage-gated Ca2+ channels

Multiple types of voltage-activated Ca2+ channels (T, L, N, P, Q, R type) coordinate Ca2+-dependent processes in neurons and neuroendocrine cells. Expressional and functional data have suggested a role for Ca(v)2.3 Ca2+ channels in endocrine processes. To verify its role in vivo, Ca(v)2.3(-/-) mutant mice were generated, thus deficient in alpha1E/R-type Ca2+ channel. Intraperitoneal injection of D-glucose showed that glucose tolerance was markedly reduced, and insulin release into plasma was impaired in Ca(v)2.3-deficient mice. In isolated islets of Langerhans from these animals, no glucose-induced insulin release was detected. Further, in stressed Ca(v)2.3-deficient mice, the rate of glucose release into the blood was only 29% of that observed for wild-type animals. Thus, the deletion of Ca(v)2.3 causes deficits not only in insulin release but also in stress-induced hyperglycemia. The complex phenotype of Ca(v)2.3-deficient mice has dual components related to endocrine and neurological defects. The present findings provide direct evidence of a functional role for the Ca(v)2.3 subunit in hormone secretion and glucose homeostasis.