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EVIDENCE FOR FUROSEMID E‐SENSITIVE Na + ‐K + ‐Cl #x2212; CO‐TRANSPORT IN LACTATING RAT MAMMARY TISSUE
Author(s) -
Shennan D. B.
Publication year - 1989
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1989.sp003363
Subject(s) - furosemide , chemistry , potassium , sodium , ouabain , ion transporter , membrane transport , symporter , ion , biochemistry , transporter , membrane , organic chemistry , gene
The transport of K + (using 86 Rb as tracer) by lactating rat mammary tissue slices has been studied in order to seek evidence for Na + ‐K + ‐Cl − co‐transport. Potassium transport was inhibited by furosemide; the locus of inhibition was at a site other than the Na + :K + pump. Replacing medium Cl − with NO 3 reduced the bidirectional movement of K + ; moreover, furosemide was without effect in a Cl − ‐free medium. Sodium replacement by N ‐methyl‐D‐glucamine acted to reduce the loop diuretic‐sensitive component of K + uptake whilst concomitantly increasing K + influx via an ouabain‐and furosemide‐resistant pathway. Potassium efflux was found to be transiently stimulated by Na + ions; this was attenuated by furosemide. Potassium egress was markedly increased via a furosemide‐insensitive pathway when salicylate was used to replace Cl − . The results are consistent with furosemide‐sensitive Na + ‐K + ‐Cl − co‐transport.