Document Detail

Inhibitory effects of chemically-different 'loop' diuretics on chloride transport across the bullfrog cornea.
MedLine Citation:
PMID:  3014820     Owner:  NLM     Status:  MEDLINE    
Frog (Rana catesbeiana) corneas were mounted in an Ussing chamber, modified to facilitate dissection and to avoid edge damage to the epithelial tissue during mounting and measurements. When bathed in Conway solution of pH 7.4 the corneas displayed highly stable electrical properties, with a transepithelial potential difference (PD) of 16.6 +/- 1.O mV and a short-circuit current (SCC) of 10.3 +/- 0.8 microA cm-2. The DC resistance was 2.0 +/- 0.15 k omega X cm2 (mean +/- SE, n = 45). An increase in the intracellular cyclic AMP level induced by prostaglandin E2 and by 3-isobutyl-1-methylxanthine (IBMX) resulted in an increase in SCC. Ortho-vanadate, an inhibitor of Na+-K+-ATPase, reduced SCC. The acidic loop diuretics furosemide, bumetanide and the levorotatory form of indacrinone (MK-196) reduced SCC by about 50% at concentrations of 500, 100 and 46 microM, respectively. The (-)form of MK-196 was four times more active than the (+)form. Dimethylation of the SO2NH2 group reduced the activity of bumetanide. The basic diuretics muzolimine (Bay G 2821) and MK-447, were found, similarly, to reduce SCC by about 50% at concentrations of 500 microM. In view of their 'high ceiling' type of saluretic effects in whole animals, these basic agents should therefore be classified as 'loop' diuretics. The effects of these structurally highly different 'loop' diuretics are similar in epithelia which secrete (cornea) and in those which absorb (the renal thick ascending limb of Henle's loop; TALH) chloride ions.(ABSTRACT TRUNCATED AT 250 WORDS)
O Eriksson; P J Wistrand
Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  127     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  1986 Jun 
Date Detail:
Created Date:  1986-08-20     Completed Date:  1986-08-20     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  SWEDEN    
Other Details:
Languages:  eng     Pagination:  137-44     Citation Subset:  IM    
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MeSH Terms
Biological Transport / drug effects
Chlorides / metabolism*
Cornea / drug effects,  metabolism*
Cyclic AMP / metabolism
Diuretics / pharmacology*
Hydrogen-Ion Concentration
Rana catesbeiana
Sodium-Potassium-Exchanging ATPase / metabolism
Reg. No./Substance:
0/Chlorides; 0/Diuretics; 60-92-4/Cyclic AMP; EC ATPase

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