DEVELOPMENT OF RENAL PHOSPHATE REGULATION

幼年未成熟动物维持正磷酸盐平衡的需要 因为增长是公认的。然而，发生在 肾脏在促进这一过程中的作用尚未阐明。目标是 目的是评估肾内磷酸盐重吸收的调节 发展。将使用显微穿刺术检查肾单位 磷酸盐重吸收部位及其对膳食和激素的反应 调节磷酸盐动态平衡的因素。我们将比较以下几个方面： 未成熟断奶大鼠(3-4周)和成年大鼠(6个月)。这个 有待检验的假设是发育中的动物表现出贪婪 由于深层肾单位的更多参与而引起的磷酸盐再吸收 肾单位远端段重吸收增强。此外，相对的 对磷酸尿酸刺激的低反应性也对肾脏有影响 保留磷酸盐。设计了特定的协议来评估 以下参数：a)磷酸盐重吸收的肾单位，b) 浅、深肾小管近端小管的转运能力 C)这些部位对磷酸尿酸刺激(高磷)的反应 饮食、甲状旁腺素、降钙素)，以及d)反应性的可能恢复 对磷尿酸激素(急性磷酸盐输注、二磷酸盐 治疗)。这些研究将提供有关 肾内机制与生长适应有关。

The need for young, immature animals to maintain positive phosphate balance for growth is well recognized. However, the adaptations that occur in the kidney to facilitate this process have not been clarified. The objective is to evaluate the intrarenal regulation of phosphate reabsorption during development. Micropuncture techniques will be used to examine the nephron sites of phosphate reabsorption and their response to dietary and hormonal factors regulating phosphate homeostasis. Comparisons will be made between immature, weaned rats (3-4 weeks) and adult rats (6 months). The hypothesis to be tested is that the developing animal displays avid phosphate reabsorption due to greater participation of deep nephrons and enhanced reabsorption in distal nephron segments. Furthermore, relative hyporesponsiveness to phosphaturic stimuli also contributes to the renal retention of phosphate. Specific protocols are designed to evaluate the following parameters: a) the nephron sites of phosphate reabsorption, b) the transport capacities of superficial and deep nephron proximal tubules, c) the response of these sites to phosphaturic stimuli (high phosphate diet, PTH, calcitonin), and d) the possible restoration of responsiveness to hhosphaturic hormones (with acute phosphate infusions, diphosphonate treatment). These studies will provide important information regarding the intrarenal mechanisms involved in the adaptations for growth.