Mayer G P, Hurst J G
Endocrinology. 1978 Jun;102(6):1803-14. doi: 10.1210/endo-102-6-1803.
Parathyroid hormone (PTH) secretion rate was measured in seven calves by using a technique which involved RIA of parathyroid venous blood collected during timed intervals and measured volumetrically. Infusion of solutions of NA2EDTA and MgCl2 into the jugular vein was used to alter plasma calcium and magnesium concentrations. In four calves, elevation of plasma magnesium concentration rapidly decreased the PTH secretion rate that had been stimulated by induced hypocalcemia. In three calves, equimolar and opposite changes in plasma calcium and magnesium concentrations were induced by simultaneous infusions of Na2EDTA and MgCl2. Despite the equimolar increase in plasma magnesium concentration, PTH secretion was increased in response to the decline in plasma calcium concentration. In three experiments, the concentration of each cation was kept constant during periods in which the concentration of the other cation was varied. The effect of variations in plasma magnesium concentration on PTH secretion rate was approximately 1/3-1/2 as great as that observed with changes in plasma calcium concentration. These observations indicate that the effect of magnesium on PTH secretion rate is similar to that of calcium, but not equipotent.
采用一种技术对7头小牛的甲状旁腺激素（PTH）分泌率进行了测定，该技术包括对定时采集的甲状旁腺静脉血进行放射免疫分析（RIA）并进行体积测量。通过向颈静脉输注Na2EDTA和MgCl2溶液来改变血浆钙和镁的浓度。在4头小牛中，血浆镁浓度升高迅速降低了由诱导性低钙血症刺激产生的PTH分泌率。在3头小牛中，通过同时输注Na2EDTA和MgCl2诱导血浆钙和镁浓度发生等摩尔且相反的变化。尽管血浆镁浓度等摩尔增加，但随着血浆钙浓度的下降，PTH分泌增加。在3个实验中，在另一种阳离子浓度变化的时间段内，每种阳离子的浓度保持恒定。血浆镁浓度变化对PTH分泌率的影响约为血浆钙浓度变化所观察到影响的1/3 - 1/2。这些观察结果表明，镁对PTH分泌率的影响与钙相似，但效力不等同。
