Maguire M E, Erdos J J
J Biol Chem. 1978 Oct 10;253(19):6633-6.
The uptake of 28Mg and 45Ca was measured in S49 lymphoma cells. The beta-adrenergic agonist (-)-isoproterenol markedly inhibited the rate of 28Mg accumulation but had no effect on 45Ca accumulation. The effect of (-)-isoproterenol was blocked by (-)-propranolol. In variants of the S49 cell line deficient in adenylate cyclase activity (cyc-) or in hormone receptor-adenylate cyclase coupling (unc), (-)-isoproterenol had no effect on 28Mg accumulation. The S49 lymphoma cells also possess prostaglandin E1 receptors coupled to adenylate cyclase, and, like (-)-isoproterenol, prostaglandin E1 decreased the rate of 28Mg uptake. Experiments with the mouse erythroleukemia cell line GM86 also showed a beta-adrenergic-mediated decrease in the rate of accumulation of 28Mg. Previous work has shown that Mg2+ increases the affinity of agonists for the beta-adrenergic receptor (Bird, S.J., and Maguire, M.E. (1978) J. Biol. Chem. 253, in press). In view of these effects of Mg2+, it is suggested that Mg2+, but not Ca2+, may regulate the sensitivity of S49 cell adenylate cyclase to stimulation by catecholamines.
在S49淋巴瘤细胞中测量了28Mg和45Ca的摄取。β-肾上腺素能激动剂（-）-异丙肾上腺素显著抑制28Mg的积累速率，但对45Ca的积累没有影响。（-）-普萘洛尔可阻断（-）-异丙肾上腺素的作用。在腺苷酸环化酶活性缺陷（cyc-）或激素受体-腺苷酸环化酶偶联缺陷（unc）的S49细胞系变体中，（-）-异丙肾上腺素对28Mg的积累没有影响。S49淋巴瘤细胞还具有与腺苷酸环化酶偶联的前列腺素E1受体，并且与（-）-异丙肾上腺素一样，前列腺素E1降低了28Mg的摄取速率。对小鼠红白血病细胞系GM86的实验也表明，β-肾上腺素能介导28Mg积累速率降低。先前的研究表明，Mg2+增加了激动剂对β-肾上腺素能受体的亲和力（Bird，S.J.和Maguire，M.E.（1978年）《生物化学杂志》253卷，即将发表）。鉴于Mg2+的这些作用，有人提出Mg2+而非Ca2+可能调节S49细胞腺苷酸环化酶对儿茶酚胺刺激的敏感性。
