Flow regulation of collecting duct endothelin-1 production

Am J Physiol Renal Physiol. 2011 Mar;300(3):F650-6. doi: 10.1152/ajprenal.00530.2010. Epub 2010 Dec 22.

Abstract

Collecting duct (CD) endothelin-1 (ET-1) is an important autocrine inhibitor of CD Na(+) reabsorption. Salt loading is thought to increase CD ET-1 production; however, definitive evidence of this, as well as understanding of the mechanisms transducing this effect, is lacking. Tubule fluid flow increases in response to Na(+) loading; hence, we studied flow modulation of CD ET-1 production. Three days of a high-salt diet increased mouse and rat inner medullary CD (IMCD) ET-1 mRNA expression. Acute furosemide infusion increased urinary ET-1 excretion in anesthetized rats. Primary cultures of mouse or rat IMCD detached in response to flow using a closed perfusion chamber, consequently a CD cell line (mpkCCDcl4) was examined. Flow increased ET-1 mRNA at shear stress rates exceeding 1 dyne/cm(2), with the maximal effect seen between 2 and 10 dyne/cm(2). Induction of ET-1 mRNA was first evident after 1 h, and most apparent after 2 h, of flow. Inhibition of calmodulin or dihydropyridine-sensitive Ca(2+) channels did not alter the flow response; however, chelation of intracellular Ca(2+) or removal of extracellular Ca(2+) largely prevented flow-stimulated ET-1 mRNA accumulation. Downregulation of protein kinase C (PKC) using phorbol 12-myristate 13-acetate, or PKC inhibition with calphostin C, markedly reduced flow-stimulated ET-1 mRNA levels. Flow-stimulated ET-1 mRNA accumulation was abolished by inhibition of phospholipase C (PLC). Taken together, these data indicate that flow increases CD ET-1 production and this is dependent on extracellular and intracellular Ca(2+), PKC, and PLC. These studies suggest a novel pathway for coupling alterations in extracellular fluid volume to CD ET-1 production and ultimately control of CD Na(+) reabsorption.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels / metabolism
  • Cells, Cultured
  • Endothelin-1 / metabolism*
  • Furosemide / pharmacology
  • Kidney Tubules, Collecting / cytology
  • Kidney Tubules, Collecting / drug effects
  • Kidney Tubules, Collecting / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Models, Animal
  • Protein Kinase C / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Endothelin / metabolism
  • Sodium / metabolism
  • Sodium Potassium Chloride Symporter Inhibitors / pharmacology
  • Sodium, Dietary / pharmacology
  • Type C Phospholipases / metabolism

Substances

  • Calcium Channels
  • Endothelin-1
  • Receptors, Endothelin
  • Sodium Potassium Chloride Symporter Inhibitors
  • Sodium, Dietary
  • Furosemide
  • Sodium
  • Protein Kinase C
  • Type C Phospholipases
  • Calcium