POTASSIUM-INDUCED DEPOLARIZATION STIMULATES SOMATOSTATIN GENE-EXPRESSION IN CULTURED FETAL-RAT CEREBROCORTICAL CELLS

The stimulatory effect of potassium depolarization upon somatostatin m RNA (SS mRNA) levels in primary cultures of fetal cerebrocortical cell s was analyzed. Depolarizing stimuli, such as 56 mM K+ concentration f or 24 hours, elicited an increase in immunoreactive somatostatin (IR-S S) release to the media and SS mRNA levels, suggesting that somatostat in secretion can be coupled to SS mRNA accumulation. These changes wer e inhibited by the Ca2+ channel antagonist verapamil (VPM). In contras t, 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 calci um ion channels.