Document Detail

Flow rate measurements in isolated perfused kidney tubules by fluorescence photobleaching recovery.
MedLine Citation:
PMID:  1760509     Owner:  NLM     Status:  MEDLINE    
We have developed a new application of the fluorescence photobleaching recovery (FPR) technique for instantaneous measurement of volume flow rates at any axial position along isolated perfused kidney tubules. The method requires fast data acquisition of emitted fluorescence through a photomultiplier (time resolution, 0.5 ms) coupled with differential interference contrast microscopy to measure luminal diameters accurately. While the tubule is perfused in vitro with an impermeant fluorophore (fluorescein sulfonate), a 20-ms bleach pulse reduces the fluorescence in the observation region by 20-25%. Fluorescence recovery is a direct function of perfusate velocity; diffusion plays no significant role in the early phase of recovery. A fluid dynamics approach to data analysis shows that fractional recovery increases linearly with time until t = L/2vm, where L is the length of the observation window and vm is the mean axial velocity. Practically, a linear regression analysis of the early recovery phase allows measurement of vm of up to 0.14 cm/s, i.e., a 40-nl/min flow rate in a 25-microns-diameter tubule. Calibration experiments in small glass tubes perfused at predetermined flow rates demonstrated good accuracy (within 10%) and reproducibility (coefficient of variation, 8.7%). In rat inner medullary collecting ducts microperfused at 4-40 nl/min, the correlation with a standard fluid collection method was excellent (r2 greater than 0.97). The method should also be suitable for the direct measurement of fluid flow rate in kidney tubules or blood vessels microperfused in vivo.
B Flamion; P M Bungay; C C Gibson; K R Spring
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Biophysical journal     Volume:  60     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  1991 Nov 
Date Detail:
Created Date:  1992-02-13     Completed Date:  1992-02-13     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1229-42     Citation Subset:  IM    
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
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MeSH Terms
Biophysical Phenomena
Body Fluids / physiology
Electronics, Medical
Kidney Tubules, Collecting / physiology*
Models, Biological
Optics and Photonics / instrumentation
Rats, Inbred Strains

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