Epithelial Na(+) channels are regulated by flow.

نویسندگان

  • L M Satlin
  • S Sheng
  • C B Woda
  • T R Kleyman
چکیده

Na(+) absorption in the renal cortical collecting duct (CCD) is mediated by apical epithelial Na(+) channels (ENaCs). The CCD is subject to continuous variations in intraluminal flow rate that we speculate alters hydrostatic pressure, membrane stretch, and shear stress. Although ENaCs share limited sequence homology with putative mechanosensitive ion channels in Caenorhabditis elegans, controversy exists as to whether ENaCs are regulated by biomechanical forces. We examined the effect of varying the rate of fluid flow on whole cell Na(+) currents (I(Na)) in oocytes expressing mouse alpha,beta,gamma-ENaC (mENaC) and on net Na(+) absorption in microperfused rabbit CCDs. Oocytes injected with mENaC but not water responded to the initiation of superfusate flow (to 4-6 ml/min) with a reversible threefold stimulation of I(Na) without a change in reversal potential. The increase in I(Na) was variable among oocytes. CCDs responded to a threefold increase in rate of luminal flow with a twofold increase in the rate of net Na(+) absorption. An increase in luminal viscosity achieved by addition of 5% dextran to the luminal perfusate did not alter the rate of net Na(+) absorption, suggesting that shear stress does not influence Na(+) transport in the CCD. In sum, our data suggest that flow stimulation of ENaC activity and Na(+) absorption is mediated by an increase in hydrostatic pressure and/or membrane stretch. We propose that intraluminal flow rate may be an important regulator of channel activity in the CCD.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Flow cytometry analysis reveals a decrease in intracellular sodium during sperm capacitation.

Mammalian sperm require time in the female tract in order to be able to fertilize an egg. The physiological changes that render the sperm able to fertilize are known as capacitation. Capacitation is associated with an increase in intracellular pH, an increase in intracellular calcium and phosphorylation of different proteins. This process is also accompanied by the hyperpolarization of the sper...

متن کامل

Nasal potential difference to detect Na+ channel dysfunction in acute lung injury.

Pulmonary fluid clearance is regulated by the active transport of Na(+) and Cl(-) through respiratory epithelial ion channels. Ion channel dysfunction contributes to the pathogenesis of various pulmonary fluid disorders including high-altitude pulmonary edema (HAPE) and neonatal respiratory distress syndrome (RDS). Nasal potential difference (NPD) measurement allows an in vivo investigation of ...

متن کامل

Ionic blockage of the light-regulated sodium channels in isolated rod outer segments

We have investigated, with osmotic techniques, the light-regulated Na+ channels in rod outer segments (ROS) and ROS fragments freshly isolated from the frog retina. Values of Na+ permeability (PNa) similar to those observed electrophysiologically in the retina were observed using the osmotic technique (continuous flow) described by Korenbrot and Cone. In the other osmotic techniques that we exp...

متن کامل

Hypoxia downregulates expression and activity of epithelial sodium channels in rat alveolar epithelial cells.

Decrease in alveolar oxygen tension may induce acute lung injury with pulmonary edema. We investigated whether, in alveolar epithelial cells, expression and activity of epithelial sodium (Na) channels and Na,K-adenosine triphosphatase, the major components of transepithelial Na transport, were regulated by hypoxia. Exposure of cultured rat alveolar cells to 3% and 0% O2 for 18 h reduced Na chan...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • American journal of physiology. Renal physiology

دوره 280 6  شماره 

صفحات  -

تاریخ انتشار 2001