Potassium-induced depolarization stimulates somatostatin gene expression in cultured fetal rat cerebrocortical cells

The stimulatory effect of potassium depolarization upon somatostatin mRNA (SS mRNA) levels in primary cultures of fetal cerebrocortical cells was analyzed. Depolarizing stimuli, such as 56 mM K+ concentration for 24 hours, elicited an increase in immunoreactive somatostatin (IR-SS) release to the media and SS mRNA levels, suggesting that somatostatin secretion can be coupled to SS mRNA accumulation. These changes were inhibited by the Ca2+ channel antagonist verapamil (VPM). In contrast, Na+ channel blockade by tetrodotoxin (TTX) did not modify the 24 h potassium-induced increase in SS mRNA. These results suggest that the induction of SS mRNA expression by K+ involves the modulation of calcium ion channels.