Krieger J E, Liard J F, Cowley A W
Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
Am J Physiol. 1990 Dec;259(6 Pt 2):H1629-36. doi: 10.1152/ajpheart.1990.259.6.H1629.
The sequential hemodynamics, fluid and electrolyte balances, and the hormonal responses to a 7-day high-salt (NaCl) intake were investigated in sodium-depleted conscious dogs (n = 6). Studies were carried out in metabolic cages mounted on sensitive load cells, which enabled continuous 24 h/day monitoring of total body weight (TBW) as an index of changes in body water. Beat-by-beat hemodynamics were determined 24 h/day. Water (700 ml/day iv) intake was maintained constant. Daily fluid and electrolyte balances and hormonal analyses were performed. An increase of daily salt intake from 8 to 120 meq increased TBW 251 +/- 44 g (P less than 0.05), which was sustained thereafter. Average 24-h mean arterial pressure (MAP) and heart rate (HR) remained unchanged. Average cardiac output (CO) increased 11% (P less than 0.05) above control values by day 2, while total peripheral resistance (TPR) decreased proportionally. CO and TPR returned to control values only when low salt was resumed. Blood volume (BV) was unchanged on day 2 as indicated by direct measurement of BV (51Cr-labeled red blood cells) or by analysis of plasma protein concentration. A 92-meq (P less than 0.05) sodium retention was observed initially, and plasma sodium concentration increased slightly. Plasma renin activity, angiotensin II, and aldosterone levels decreased significantly, whereas vasopressin and atrial natriuretic peptide levels remained unchanged. In summary, chronic high-salt intake resulted in a net retention of water and sodium with no changes in MAP, HR, or BV. The rise in CO was offset by a reduction in TPR, which appeared at least in part related to angiotensin II suppression.
对6只钠缺乏的清醒犬进行了为期7天高盐（氯化钠）摄入的序贯血流动力学、液体和电解质平衡以及激素反应研究。实验在安装于灵敏称重传感器上的代谢笼中进行，可连续24小时监测总体重（TBW），以此作为身体水分变化的指标。每天24小时测定逐搏血流动力学。静脉输注水（700毫升/天）的摄入量保持恒定。进行每日液体和电解质平衡及激素分析。每日盐摄入量从8毫当量增加到120毫当量，使TBW增加251±44克（P<0.05），此后持续增加。平均24小时平均动脉压（MAP）和心率（HR）保持不变。到第2天，平均心输出量（CO）比对照值增加11%（P<0.05），而总外周阻力（TPR）成比例下降。只有恢复低盐饮食时，CO和TPR才恢复到对照值。通过直接测量血容量（BV）（51Cr标记红细胞）或分析血浆蛋白浓度表明，第2天BV无变化。最初观察到92毫当量（P<0.05）的钠潴留，血浆钠浓度略有升高。血浆肾素活性、血管紧张素II和醛固酮水平显著降低，而血管加压素和心房利钠肽水平保持不变。总之，慢性高盐摄入导致水和钠的净潴留，MAP、HR或BV无变化。CO的升高被TPR的降低所抵消，这至少部分与血管紧张素II的抑制有关。
