Feng J Q, Clark N B
Department of Medicine, University of Texas Health Science Center, San Antonio 78284.
Am J Physiol. 1994 Jul;267(1 Pt 2):R295-302. doi: 10.1152/ajpregu.1994.267.1.R295.
Renal clearance studies were performed in chicks 1, 5, and 9 days after hatching. Calcium gluconate was infused to block endogenous parathyroid hormone (PTH) secretion, whereas ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) was infused to stimulate endogenous PTH secretion. PTH, dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), or vehicle was administered intravenously. In 9-day-old birds, urinary cAMP and inorganic phosphate excretion fell dramatically after calcium loading and rose significantly after PTH, DBcAMP, or EGTA administration. These manipulations had no significant effect on excretion of calcium or inorganic phosphate in 1-day-old hatchlings. Five day-old-chicks gave an intermediate response. All three age groups, as well as 15-day-embryos, showed sharp increases in urinary cAMP values after PTH administration. Thus the adult response pattern to PTH appears to develop gradually during the first week after hatching or to be suppressed during the perinatal period, whereas the second-messenger response to the hormone, indicating hormone-receptor interaction, is present from late embryogenesis onward.
在雏鸡孵化后1天、5天和9天进行了肾脏清除率研究。输注葡萄糖酸钙以阻断内源性甲状旁腺激素（PTH）分泌，而输注乙二醇双（β-氨基乙基醚）-N，N，N'，N'-四乙酸（EGTA）以刺激内源性PTH分泌。静脉内给予PTH、二丁酰腺苷3'，5'-环磷酸（DBcAMP）或赋形剂。在9日龄的雏鸡中，钙负荷后尿cAMP和无机磷排泄显著下降，而给予PTH、DBcAMP或EGTA后则显著上升。这些操作对1日龄雏鸡的钙或无机磷排泄没有显著影响。5日龄雏鸡的反应介于两者之间。所有三个年龄组以及15日龄胚胎在给予PTH后尿cAMP值均急剧增加。因此，成年鸡对PTH的反应模式似乎在孵化后的第一周逐渐形成，或者在围产期受到抑制，而对该激素的第二信使反应，表明激素-受体相互作用，从胚胎后期就已存在。
