EFFECTS OF POTASSIUM BICARBONATE ON DISTAL NEPHRON NA-K-ATPASE IN ADRENALECTOMIZED RABBITS
EFFECTS OF POTASSIUM BICARBONATE ON DISTAL NEPHRON NA-K-ATPASE IN ADRENALECTOMIZED RABBITS
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DOI：
10.1007/bf00584759
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发表时间：
1987-06-01
影响因子：
4.5
通讯作者：
NARANG, N
中科院分区：
文献类型：
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作者：
GARG, LC;NARANG, N
已证明在存在和不存在醛固酮的情况下，KCl都会影响连接小管（CNT）和皮质集合管（CCD）中的Na-K-ATP酶活性。为了研究K+对Na-K-ATP酶的非醛固酮依赖性作用是否可由其他K+盐产生，我们研究了饲料KHCO 3对肾上腺切除（ADX）家兔4个肾单位节段Na-K-ATP酶和哇巴因不敏感的Mg-ATP酶活性的影响。所检查的节段为：远曲小管（DCT）、CNT、CCD和髓集合管（MCD）。除第1 ~ 4组的KHCO 3含量分别为100、300、500和700 meq/kg外，所有日粮的组成相似。在饮食中增加KHCO 3增加K+排泄（7 × 10 - 4）。尿pH值为6.6 ~ 8.3。当饲粮KHCO 3增加到700 meq/kg时，CCD中的Na-K-ATPase活性增加>200%。此段Na-K-ATP酶活性与稳态血浆K ~+和尿K ~+排泄量呈线性关系。然而，Na-K-ATP酶活性的CCD是较低的KHCO 3喂养的ADX兔比氯化钾喂养的动物在类似的条件下研究。不同KHCO 3-日粮组间DCT、CNT和MCD的Na-K-ATP酶活性差异不显著。结论：膳食中KHCO_3的摄入也可以影响CCD中的Na-K-ATPase活性，而不依赖于醛固酮。
Na-K-ATPase activity in the connecting tubule (CNT) and cortical collecting duct (CCD) has been shown to be influenced by KCl both in the presence and in the absence of aldosterone. To investigate if the aldosterone-independent effect of K+ on Na-K-ATPase can be produced by other K+ salts, we studied the effects of dietary KHCO3 on Na-K-ATPase and ouabain-insensitive Mg-ATPase activities in four nephron segments of adrenalectomized (ADX) rabbits. The segments examined were: the distal convoluted tubule (DCT), CNT, CCD and medullary collecting duct (MCD). All diets were similar in composition except their KHCO3 contents which were 100, 300, 500 and 700 meq/kg in groups 1 to 4 respectively. Increasing KHCO3 in the diet increased K+ excretion (7 .times.) and urine pH (6.6 to 8.3). Na-K-ATPase activity in the CCD increased >200% as dietary KHCO3 was increased to 700 meq/kg. There was a linear relation between Na-K-ATPase activity in this segment and steady state plasma K+ as well as K+ excretion in the urine. However, Na-K-ATPase activity in the CCD was lower in KHCO3-fed ADX rabbits than the K Cl-fed animals studied previously under similar conditions. There were no significant differences in Na-K-ATPase activities in DCT, CNT and MCD among the four groups given different KHCO3-diets. It is concluded that dietary intake of KHCO3 can also influence Na-K-ATPase activity in the CCD independent of aldosterone.