In:
American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 283, No. 6 ( 2002-12-01), p. F1337-F1350
Abstract:
Inner medullary collecting ducts (IMCD) are the final nephron segments through which urine flows. To investigate epithelial ion transport in human IMCD, we established primary cell cultures from initial (hIMCD i ) and terminal (hIMCD t ) inner medullary regions of human kidneys. AVP, PGE 2 , and forskolin increased cAMP in both hIMCD i and hIMCD t cells. The effects of AVP and PGE 2 were greatest in hIMCD i ; however, forskolin increased cAMP to the same extent in hIMCD i and hIMCD t . Basal short-circuit current ( I SC ) of hIMCD i monolayers was 1.4 ± 0.5 μA/cm 2 and was inhibited by benzamil, a Na + channel blocker. 8-Bromo-cAMP, AVP, PGE 2 , and forskolin increased I SC ; the current was reduced by blocking PKA, apical Cl − channels, basolateral NKCC1 (a Na + -K + -2Cl − cotransporter), and basolateral Cl − /HCO[Formula: see text]exchangers. In fluid transport studies, hIMCD i monolayers absorbed fluid in the basal state and forskolin reversed net fluid transport to secretion. In hIMCD t monolayers, basal current was not different from zero and cAMP had no effect on I SC . We conclude that AVP and PGE 2 stimulate cAMP-dependent Cl − secretion by hIMCD i cells, but not hIMCD t cells, in vitro. We suggest that salt secretion at specialized sites along human collecting ducts may be important in the formation of the final urine.
Type of Medium:
Online Resource
ISSN:
1931-857X
,
1522-1466
DOI:
10.1152/ajprenal.00165.2002
Language:
English
Publisher:
American Physiological Society
Publication Date:
2002
detail.hit.zdb_id:
1477287-5
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