Chloride transport in the rat S1 proximal tubule
K. R. Wong, C. A. Berry and M. G. Cogan Department of Medicine, University of California, San Francisco, USA. In vivo microperfusion was used to elucidate the modes and regulation of the powerful chloride transport system resident in the rat early (S1) proximal convoluted tubule (PCT). From a comple...
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Veröffentlicht in: | American journal of physiology. Renal physiology 1995-04, Vol.268 (4), p.723-F729 |
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Zusammenfassung: | K. R. Wong, C. A. Berry and M. G. Cogan
Department of Medicine, University of California, San Francisco, USA.
In vivo microperfusion was used to elucidate the modes and regulation of
the powerful chloride transport system resident in the rat early (S1)
proximal convoluted tubule (PCT). From a complete, glomerular
ultrafiltrate-like perfusate, omission of organic solutes reduced chloride
absorption by 93 peq.mm-1.min-1 (302 +/- 10 to 209 +/- 24, P < 0.001).
From a high-chloride perfusate (a relatively pure NaCl solution devoid of
bicarbonate and organic solutes), luminal addition of the active transport
inhibitor cyanide reduced chloride absorption by 153 peq.mm-1.min-1 (632
+/- 17 to 479 +/- 9, P < 0.001). Active transport was also estimated
directly as 121 +/- 4 peq.mm-1.min-1 using a solution in which sodium
isethionate isosmotically replaced bicarbonate and organic solutes,
preventing development of a chloride gradient. Intravenous angiotensin II
caused a stimulation of chloride absorption from a high-chloride perfusate
by 55 peq.mm-1.min-1 (632 +/- 17 to 687 +/- 14, P < 0.05), which was
partially cyanide-sensitive (510 +/- 6 peq.mm-1.min-1). In conclusion, the
components of the normal S1 PCT chloride reabsorption (approximately 300
peq.mm-1.min-1) from the glomerular ultrafiltrate consist of the following:
active transport (40-50%), which can be regulated by angiotensin II;
sodium-coupled organic solute transport (30%); and passive, chloride
concentration gradient-driven transport (20-25%). |
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ISSN: | 0363-6127 0002-9513 1931-857X 2161-1157 1522-1466 |
DOI: | 10.1152/ajprenal.1995.268.4.F723 |