Effects of Nifedipine on Prolactin,Growth Hormone,and Luteinizing Hormone Release by Rat Anterior Pituitary in Vitro

Summary

The release of prolactin, GH, and LH was monitored by radioimmunoas-say in rat anterior pituitary tissue incubated in Krebs-Ringer bicarbonate medium. Nife-dipine, a strong Ca²⁺ blocker, at 10, 100, and 1000 ng/ml inhibited the release of prolactin in a dose-related manner, but did not inhibit the release of GH and LH. This drug also blocked the TRH-induced GH release and the LH-RH-induced LH release. These results indicate that the release of prolactin may be more closely tied to Ca²⁺ influx from extracellular fluid and with stimulus-secretion coupling than the release of GH and LH and that Ca²⁺ may also play a role in the release of anterior pituitary hormones induced by releasing hormones.