Calcium Antagonists and Hormone Release

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Abstract
Twenty-five patients with various syndromes of pituitary hyperfunction, of tumoral and nontumoral origin, were infused with verapamil (VE), a Ca2+-channel blocker (5 mg/h × 3 h) to assess the calcium dependence of the augmented hormone secretion. In 5 hypogonadal women with elevated gonadotropin secretion, VE produced a marked inhibition of LH (54.6%) and FSH (49.4%) release, comparable to that observed in normal subjects who were infused with VE. In 5 patients with latent or mild hypothyroidism, TSH levels decreased during the VE infusion, and the magnitude of the decrease was directly correlated with the basal levels (r = 0.986, p < 0.01). In patients harboring a pituitary tumor, differential effects of VE infusion were observed: it induced an inhibition (28.5%) of ACTH secretion in patients with Cushing’s disease; in acromegalic patients, no alterations in HGH levels were noted; on the contrary, in prolactinoma patients, a clear PRL increment (47.2%) was present. These experiments confirm that the need for extracellular Ca2+ varies from hormone to hormone and that VE infusion can modify the secretion of pituitary hormone in a hypersecretory state, as well as those hormones which are unaffected by VE infusion in basal condition.

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