Altered collecting duct adenylyl cyclase content in collecting duct endothelin-1 knockout mice.
BACKGROUND
Endothelin-1 (ET-1) inhibition of vasopressin (AVP)-stimulated water reabsorption by the inner medullary collecting duct (IMCD) is associated with reduced cAMP accumulation. To determine the effect of ET-1 deficiency, AVP-stimulated cAMP responsiveness was assessed in IMCD from mice with collecting duct-specific deletion of ET-1 (CD ET-1 KO) and from control animals.


METHODS
Cyclic AMP production, adenylyl cyclase (AC) mRNA, and AC protein were measured in acutely isolated IMCD.


RESULTS
CD ET-1 KO IMCD had enhanced AVP-stimulated cAMP accumulation. Inhibition of calcium-stimulated AC using BAPTA did not prevent enhanced AVP responsiveness in CD ET-1 KO IMCD. Factors known to be modified by ET-1, including nitric oxide, cyclooxygenase metabolites, and superoxide did not affect the increased AVP responsiveness of CD ET-1 KO IMCD. Differential V2 receptor or G-protein activity was not involved since CD ET-1 KO IMCD had increased cAMP accumulation in response to forskolin and/or cholera toxin. CD ET-1 KO did not affect mRNA or protein levels of AC3, one of the major known collecting duct AC isoforms. However, the other known major collecting duct AC isoform (AC5/6) did have increased protein levels in CD ET-1 KO IMCD, although AC5 (weak signal) and 6 mRNA levels were unchanged.


CONCLUSIONS
ET-1 deficiency increases IMCD AC5/6 content, an effect that may synergize with acute ET-1 inhibition of AVP-stimulated cAMP accumulation.
Strait
Kevin A
KA
Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA. kevin.strait@hsc.utah.edu
Stricklett
Peter K
PK
Kohan
Donald E
DE
D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D019332:Endothelin-1 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics; D005260:Female; D007685:Kidney Tubules, Collecting / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic
D019332:Endothelin-1; D000262:Adenylyl Cyclases