[The effect of an intravenous calcium load on plasma prolactin in man (author's transl)]

Eighteen male volunteers, from 20 to 35 years, were studied after an overnight fast and in a resting phase. Nine of them were injected i.v. at 09.00 h with calcium (180 mg Ca in 20 ml), nine controls received the same volume of 0,9% NaCl. Plasma PRL, calcium, PTH, and urinary cyclic AMP were determined just before i.v. injection and 1, 2 and 3 hours later. In the controls, plasma PRL was decreased after the i.v. injection of 0.9% NaCl. Plasma calcium, PTH and urinary cyclic AMP levels were unchanged. In the calcium treated-group, plasma PRL, PTH and urinary cyclic AMP decreased progressively. No significant difference in plasma PRL levels was observed between the two groups. A rise in plasma calcium produced by i.v. calcium injection (+ 1 mg/100 ml 1 hour after injection), sufficient to decrease plasma PTH and urinary cyclic AMP, did not change the plasma prolactin level in man.