45Ca2+ uptake and peptide hormones secretion in the presence of excess Mg2+ content

Studies have been performed on the relationship between PRL and GH production and the 45Ca2+ influx in high magnesium content in vitro. The obtained data show that an elevated magnesium concentration in Krebs-Ringer solution is capable of inhibiting some hormonal function of the pituitary gland. It has been found, that PRL and GH released into the media in normal KRB solution revealed nearly two times higher concentration than in the presence of high Mg2+. Instead the cellular iPRL and iGH did not show any significant differences in control and in treated cultures. The incorporation of 4.5-3H-leucine into the prolactin and growth hormone demonstrate a significant decrease in the presence of high Mg2+ indicating that the ion is able to inhibit the secretion of newly synthesized PRL an GH. High concentration of Mg2+ abolished either the stimulation effect of releasing hormones on calcium uptake.