Nakai M, Fukase M, Yamaguchi T, Tsukamoto T, Fujii N, Fujita T
Department of Medicine, Kobe University School of Medicine, Japan.
J Bone Miner Res. 1990 Oct;5(10):995-1002. doi: 10.1002/jbmr.5650051002.
The action mechanism of hPTH and hPTHrP-(1-34) on phosphate uptake in opossum kidney (OK) cells was studied using [Nle8,18Tyr34]hPTH-(3-34)-NH2, a potent competivie inhibitor of adenylate cyclase-coupled PTH receptor. We examined the effects of hPTH-(1-34), hPTHrP-(1-34), and hPTH-(3-34) separately or in combination on the change in renal cyclic AMP production and phosphate uptake in OK cells. Both hPTH-(1-34) and hPTHrP-(1-34) stimulated intracellular cyclic AMP production to the same degree at concentrations between 10(-10) and 10(-7) M and inhibited phosphate uptake equipotently on a molar basis (27.5 +/- 2.0 and 33.2 +/- 1.2% inhibition at 10(-7) M, respectively). Both exogenous addition of (Bu)2cAMP and endogenous stimulation of cAMP by forskolin inhibited phosphate uptake in a dose-dependent manner. Cyclic AMP production induced by either hPTH-(1-34) or hPTHrP-(1-34) was inhibited by both [Nle8,18Tyr34]-hPTH-(3-34)-NH2 and [Tyr34]-hPTH-(7-34)-NH2. However, [Nle8,18Tyr34]hPTH-(3-34)-NH2 and [Tyr34]-hPTH-(7-34)-NH2 inhibited hPTH-induced cAMP production more strongly. The inhibitory action of phosphate uptake by hPTH-(1-34) and hPTHrP-(1-34) was prevented in the presence of a 100-fold greater concentration of [Nle8,18Tyr34]hPTH-(3-34)-NH2. The antagonistic action of [Nle8,18Tyr34]hPTH-(3-34)-NH2 on the inhibition of phosphate uptake induced by hPTH-(1-34) and hPTHrP-(1-34) became weaker with time (0-120 minutes), and [Nle8,18Tyr34]hPTH-(3-34)-NH2 did not antagonize the inhibition of phosphate uptake induced by hPTHrP-(1-34) at 120 minutes of incubation.(ABSTRACT TRUNCATED AT 250 WORDS)
使用[异亮氨酸8,18；酪氨酸34]人甲状旁腺激素（hPTH）-(3 - 34)-NH₂（一种腺苷酸环化酶偶联的甲状旁腺激素受体的强效竞争性抑制剂）研究了hPTH和hPTHrP-(1 - 34)对负鼠肾（OK）细胞中磷酸盐摄取的作用机制。我们分别或联合检测了hPTH-(1 - 34)、hPTHrP-(1 - 34)和hPTH-(3 - 34)对OK细胞中肾环磷酸腺苷（cAMP）生成变化和磷酸盐摄取的影响。在10⁻¹⁰至10⁻⁷ M浓度范围内，hPTH-(1 - 34)和hPTHrP-(1 - 34)同等程度地刺激细胞内cAMP生成，并且在摩尔基础上等效抑制磷酸盐摄取（在10⁻⁷ M时分别抑制27.5±2.0%和33.2±1.2%）。外源性添加双丁酰环磷腺苷（(Bu)₂cAMP）和福司可林对内源性cAMP的刺激均以剂量依赖性方式抑制磷酸盐摄取。[异亮氨酸8,18；酪氨酸34]hPTH-(3 - 34)-NH₂和[酪氨酸34]hPTH-(7 - 34)-NH₂均抑制hPTH-(1 - 34)或hPTHrP-(1 - 34)诱导的cAMP生成。然而，[异亮氨酸8,18；酪氨酸34]hPTH-(3 - 34)-NH₂和[酪氨酸34]hPTH-(7 - 34)-NH₂更强烈地抑制hPTH诱导的cAMP生成。在存在高100倍浓度的[异亮氨酸8,18；酪氨酸34]hPTH-(3 - 34)-NH₂时，hPTH-(1 - 34)和hPTHrP-(1 - 34)对磷酸盐摄取的抑制作用被阻断。[异亮氨酸8,18；酪氨酸34]hPTH-(3 - 34)-NH₂对hPTH-(1 - 34)和hPTHrP-(1 - 34)诱导的磷酸盐摄取抑制的拮抗作用随时间（0 - 120分钟）减弱，并且在孵育120分钟时，[异亮氨酸8,18；酪氨酸34]hPTH-(3 - 34)-NH₂不拮抗hPTHrP-(1 - 34)诱导的磷酸盐摄取抑制。（摘要截断于250字）
