Wong N L, Wong E F, Hu D C
Department of Medicine, University Hospital, University of British Columbia, Vancouver, Canada.
Metabolism. 1991 May;40(5):474-7. doi: 10.1016/0026-0495(91)90227-n.
Previous studies have shown that acute calcium load causes an increase in circulating plasma atrial natriuretic factor (ANF) levels. The present study was conducted to examine the effect of high dietary calcium on ANF release. Experiments were performed on two groups of male Wistar rats. Hypercalcemic (n = 12) and normocalcemic (n = 12) animals were placed on a high and normal calcium diet, respectively, for 14 days before study. A 24-hour renal clearance was conducted on all animals before superfusion studies. Clearance results showed that high dietary calcium induced a significant increase in plasma calcium (2.69 +/- 0.02 v 2.90 +/- 0.77 mmol/L; P less than .01). This elevation is plasma calcium was associated with a marked increase in calcium excretion (fractional excretion of calcium, 1.91% +/- 0.33% v 8.17% +/- 0.11%, and was correlated with a significant increase in plasma ANF levels (97 +/- 6 v 167 +/- 20 pg/mL). We also measured immunoreactive ANF in the atria of hypercalcemic and normocalcemic rats. ANF content and concentration in the atria were lower in hypercalcemic (465 +/- 36 ng/mg) than in normocalcemic rats (635 +/- 30 ng/mg). This implies that ANF secretion is stimulated by hypercalcemia. To examine this directly, the right atrium from hypercalcemic and normocalcemic rats was superfused in a modified Langendorff preparation. Spontaneous release of ANF from the isolated right atria of hypercalcemic animals (19 +/- 0.8 pg/min/mg) was significantly higher (P less than .01) than from the normocalcemic rats (8.6 +/- 0.3 pg/min/mg). These results suggest that elevation of plasma ANF levels in hypercalcemia is due to an increase in ANF secretion.
先前的研究表明，急性钙负荷会导致循环血浆心钠素（ANF）水平升高。本研究旨在探讨高钙饮食对ANF释放的影响。实验在两组雄性Wistar大鼠上进行。高钙血症组（n = 12）和正常钙血症组（n = 12）动物在研究前分别给予高钙和正常钙饮食14天。在进行灌流研究之前，对所有动物进行了24小时的肾脏清除率测定。清除率结果显示，高钙饮食导致血浆钙显著升高（2.69±0.02对2.90±0.77 mmol/L；P＜0.01）。血浆钙的这种升高与钙排泄的显著增加相关（钙分数排泄，1.91%±0.33%对8.17%±0.11%），并且与血浆ANF水平的显著升高相关（97±6对167±20 pg/mL）。我们还测量了高钙血症和正常钙血症大鼠心房中的免疫反应性ANF。高钙血症大鼠心房中的ANF含量和浓度（465±36 ng/mg）低于正常钙血症大鼠（635±30 ng/mg）。这意味着高钙血症刺激了ANF的分泌。为了直接验证这一点，将高钙血症和正常钙血症大鼠的右心房在改良的Langendorff装置中进行灌流。高钙血症动物分离的右心房中ANF的自发释放（19±0.8 pg/min/mg）显著高于正常钙血症大鼠（8.6±0.3 pg/min/mg）（P＜0.01）。这些结果表明，高钙血症时血浆ANF水平的升高是由于ANF分泌增加所致。
