To study the role of Ca2+ in the pathogenesis of pituitary growth hormone secreting adenomas

the function of Ca2+ in 23 cases of human Prturtary GH-secreting adenoma was investigated in monolayer cell culture. It was found that Ca2+ channel blockers nicardipin and nifedipin inhibrted basal and growth hormone releasing hormone （GRH）stimulated GH secretion in 87. 5 % and 100. 0 % of the GH adenomas . respectively

demonstrating that in most human pituitary GH adenomas

the basal and GRH regulated GH secretion is Ca2+ dependent. The GRH and sometostatin （SRIF） agonist octreotide regulated the processes of GH secretion via Ca2+ had defects in different steps including receptor

postreceptor Ca2+ channel and Ca2+GH secreting coupling in 6 （66. 6%） and 5 （55. 5 % ） cases of 9 GH adenomas respectively. Among them

the defects in GRH receptor and SRIF regulated Ca2+ channel are the main causes of the dysfunction of GH adenomas. These defects may be related to GH hypersecretion in GH adenomas. Our data provides advance evidences for intrinsic defects of GH adenomas.