The epithelial sodium channel (ENaC) is important for the long-term control of Na(+) homeostasis and blood pressure. Our previous studies demonstrated that Copper Metabolism Murr1 Domain-containing protein 1 (COMMD1; previously known as Murr1), a protein involved in copper metabolism, inhibited amiloride-sensitive current in Xenopus laevis oocytes expressing ENaC (J Biol Chem 279: 5429, 2004). ...

Furosemide administration stimulates distal acidification. This has been attributed to the increased lumen-negative voltage in the distal nephron, but the aspect of regulatory mechanisms of H(+)-ATPase has not been clear. The purpose of this study is to investigate whether chronic administration of diuretics alters the expression of H(+)-ATPase and whether electrogenic Na(+) reabsorption is inv...

KIRSCHNER, LEONARD B., LEWIS GREEN~ALD, AND THEODORE H. KERSTETTER. Effect of amiloride on sodium transport across body surfaces of freshwater animals. Am. J. Physiol. 224(4): 832-837. 1973.-Amiloride, added to an external bathing solution at a concentration of 1 X 10m4 M, inhibited sodium influx in intact trout (79 %), frogs (460/,), and crayfish (90 yO). It had no effect on efflux across the ...

In lithium-induced nephrogenic diabetes insipidus (NDI), alterations in renal medullary osmolyte concentrations have been assumed but never investigated. Amiloride can modify lithium-induced NDI, but the impact of amiloride in lithium-induced NDI on renal medullary osmolytes, aquaporins, and urea transporters is unknown and is the basis of this study. Rats fed lithium (60 mmol/kg dry food) over...

Renal Na(+) and K(+) excretion was measured in rats with varying dietary K(+) intake. The requirement for channel-mediated distal nephron Na(+) reabsorption was assessed by infusing the animals with the K(+)-sparing diuretic amiloride via osmotic minipumps. At infusion rates of 2 nmol/min, the concentration of amiloride in the urine was 38 microM, corresponding to concentrations of 9-23 microM ...

KIRSCHNER, LEONARD B., LEWIS GREEN~ALD, AND THEODORE H. KERSTETTER. Effect of amiloride on sodium transport across body surfaces of freshwater animals. Am. J. Physiol. 224(4): 832-837. 1973.-Amiloride, added to an external bathing solution at a concentration of 1 X 10m4 M, inhibited sodium influx in intact trout (79 %), frogs (460/,), and crayfish (90 yO). It had no effect on efflux across the ...

Amiloride-sensitive Na+ absorption is a well-described feature of numerous transporting epithelia in vertebrates. Yet, very little is known about this important physiological process regarding invertebrates. In the present paper, we compare vertebrate Na+ absorption mediated by the amiloride-sensitive epithelial Na+ channel (ENaC) and its invertebrate counterpart. We used the dorsal skin of the...

Endothelial cells from brain microvessels form the blood-brain barrier. Brain microvessels and endothelial cells isolated from rat brain microvessels express an amiloride-sensitive cationic channel that was characterized using [3H]phenamil binding and patch-clamp experiments. [3H]Phenamil, a labeled amiloride analog, recognizes a single family of binding sites with a dissociation constant of 20...

The inner medullary collecting duct (IMCD) effects net sodium reabsorption under the control of volume regulatory hormones, including atrial natriuretic peptides (ANP). These studies examined the mechanisms of sodium transport and its regulation by ANP in fresh suspensions of IMCD cells. Sodium uptake was inhibited by amiloride but insensitive to furosemide, bu-metanide, and hydrochlorthiazide....

The epithelial Na+ channel ENaC mediates transepithelial Na+ transport in the distal kidney, the colon, and the lung and is a key element for the maintenance of Na+ balance and the regulation of blood pressure. Mutagenesis studies have identified residues alphaS583 and the homologous betaG525 and gammaG537 in the outer pore entrance that are critical for ENaC block by the K+-sparing diuretic am...