Quamme G A, Wong N L, Sutton R A, Dirks J H
Am J Physiol. 1975 Jul;229(1):200-5. doi: 10.1152/ajplegacy.1975.229.1.200.
Sodium and calcium are normally reabsorbed in parallel in the renal tubule. Both parathyroid hormone (PTH) and thiazide diuretics may influence this relationship. This study was designed to show whether the dissociation of Na from Ca transport produced by thiazides is dependent upon the presence of PTH. Hydropenic thyroparathyroidectomized (TPTX) dogs were given chlorothiazide alone and together with PTH. Chlorothiazide alone significantly increased fractional excretion of sodium (0.5 +/- 0.3-5.6 +/- 0.3%) and calcium (0.74 +/- 0.18-1.4 +/- 0.24%). However, the Ca/Na excretion ratio fell markedly from 1.57 to 0.24%. Micropuncture revealed this dissociation to occur at the distal tubule. Proximal reabsorption of water, sodium, and calcium were inhibited to an equal extent. However, distal fractional sodium reabsorption fell 10% whereas calcium reabsorption remained unchanged following chlorothiazide administration in TPTX animals. When phosphaturic doses of PTH were administered with chlorothiazide, no significant changes were observed in calcium or sodium reabsorption. It is concluded that PTH plays no role in the dissociation of sodium from calcium reabsorption resulting from acute chlorothiazide administration.
钠和钙通常在肾小管中并行重吸收。甲状旁腺激素（PTH）和噻嗪类利尿剂均可影响这种关系。本研究旨在表明噻嗪类药物导致的钠与钙转运解离是否依赖于PTH的存在。对禁水的甲状腺甲状旁腺切除（TPTX）犬单独给予氯噻嗪以及同时给予氯噻嗪和PTH。单独给予氯噻嗪显著增加了钠（0.5±0.3% - 5.6±0.3%）和钙（0.74±0.18% - 1.4±0.24%）的排泄分数。然而，钙/钠排泄率从1.57%显著降至0.24%。微穿刺显示这种解离发生在远端小管。近端水、钠和钙的重吸收受到同等程度的抑制。然而，在TPTX动物中给予氯噻嗪后，远端钠重吸收分数下降了10%，而钙重吸收保持不变。当给予氯噻嗪的同时给予促尿磷排泄剂量的PTH时，钙或钠的重吸收未观察到显著变化。得出的结论是，PTH在急性给予氯噻嗪导致的钠与钙重吸收解离过程中不起作用。
