Abstract:
:In order to investigate the effect of chronic sodium depletion on renal proximal tubular reabsorption, studies were performed in conscious, unrestrained Brattleboro rats. Since these animals lack circulating vasopressin, fractional water reabsorption in the distal nephron can be assumed to be constant and changes in urine flow rate should therefore reflect changes in end-proximal fluid delivery. Sodium depletion was induced by placing rats on a low-sodium diet (4 mmol Na (kg dry wt)-1) and administering frusemide (40 mg (kg body wt)-1) by gavage on the first 2 days. Extracellular volume, measured after 7-9 days, was reduced by 19% (P < 0.02) as compared with that of rats maintained on a control diet. Urine flow rate, measured during days 4-7 of the low-sodium diet, was significantly lower than that of control rats (142 +/- 8 vs. 168 +/- 5 ml day-1, P < 0.01). Since renal papillary interstitial fluid osmolality was found to be reduced in the sodium-depleted rats (693 +/- 38 vs. 812 +/- 36 mosmol (kg H2O)-1, P < 0.05), it is unlikely that water reabsorption from sites beyond the proximal tubule had increased. The observed reduction in urine flow rate therefore strongly suggests a reduction in end-proximal fluid delivery. In the second part of the study, a single group of Brattleboro rats was used, in which osmotic minipumps were implanted in the peritoneal cavity for continuous infusion of [14C]inulin. After recovery from the operation, the rats were maintained on a control diet for 6 days (pre-control period), then subjected to sodium depletion (low-sodium diet for 6 days, frusemide administration on the first 2 days), and finally returned to the control diet for 6 days, with access to 0.46 M NaCl solution on the first 2 days, in order to restore sodium balance (post-control period). On the final 2 days of each phase, urine flow rate and [14C]inulin clearance (= glomerular filtration rate, GFR) were measured. Urine flow rates during the pre-control, sodium depletion and post-control periods were 169 +/- 7, 132 +/- 8 (P < 0.001) and 176 +/- 8 microliters min-1, respectively; corresponding values for fractional water excretion were 7.0 +/- 0.3, 6.0 +/- 0.5 (P < 0.01) and 7.4 +/- 0.4%. Only a small reduction GFR, of borderline statistical significance, was observed during sodium depletion.(ABSTRACT TRUNCATED AT 250 WORDS)
journal_name
Exp Physioljournal_title
Experimental physiologyauthors
Shirley DG,Skinner Jdoi
10.1113/expphysiol.1994.sp003749subject
Has Abstractpub_date
1994-03-01 00:00:00pages
161-73issue
2eissn
0958-0670issn
1469-445Xjournal_volume
79pub_type
杂志文章abstract:NEW FINDINGS:What is the topic of this review? This review is principally concerned with results from studies of the pulmonary vasculature in humans, particularly in relation to hypoxia and rare diseases that affect oxygen sensing. What advances does it highlight? This review highlights the degree to which the hypoxia-...
journal_title:Experimental physiology
pub_type: 杂志文章,评审
doi:10.1113/expphysiol.2014.080507
更新日期:2015-11-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1994.sp003817
更新日期:1994-11-01 00:00:00
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更新日期:2003-07-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1994.sp003772
更新日期:1994-05-01 00:00:00
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更新日期:2020-12-01 00:00:00
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pub_type: 杂志文章
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更新日期:2017-11-01 00:00:00
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pub_type: 杂志文章
doi:10.1113/expphysiol.2011.062927
更新日期:2012-08-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.2012.068312
更新日期:2013-02-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/EP086922
更新日期:2018-06-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1995.sp003826
更新日期:1995-01-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:
更新日期:2000-11-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
doi:10.1113/expphysiol.1997.sp004056
更新日期:1997-07-01 00:00:00
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journal_title:Experimental physiology
pub_type: 临床试验,杂志文章
doi:
更新日期:2000-05-01 00:00:00
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更新日期:2005-03-01 00:00:00
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更新日期:2002-03-01 00:00:00
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doi:10.1113/expphysiol.2007.038026
更新日期:2007-07-01 00:00:00
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doi:10.1113/expphysiol.2011.060491
更新日期:2012-01-01 00:00:00
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更新日期:2006-09-01 00:00:00
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更新日期:2014-11-01 00:00:00
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更新日期:2016-08-01 00:00:00
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pub_type: 杂志文章,评审
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更新日期:2000-03-01 00:00:00
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更新日期:2017-06-01 00:00:00
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journal_title:Experimental physiology
pub_type: 杂志文章
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更新日期:1996-11-01 00:00:00