[The role of Ca2+ in the pathogenesis of human pituitary GH-secreting adenomas]

Abstract

Effects of Ca2+ channel blockers (nicardipin and nifedipin) and Ca2+ ionophore A23187 on the basal secretion and on the secretion stimulated by GRH or inhibited by SMS, a SRIF analogne of GH were investigated in monolayer cell cultures of 23 cases of human pituitary GH-secreting adenomas. The roles of GRH and SMS in 45Ca influx were investigated also. The GH secretion of most GH adenomas was depended on Ca2+, but the abnormality in different link of GH secretion mediated by Ca2+ was observed. The defects of receptor and post-receptor including Ca2+ channel and Ca(2+)-GH secretion couple regulated by GRH and SRIF were found in 66.7% and 55.6% of GH adenomas respectively. These abnormalities may contribute to GH hypersecretion in GH adenomas.