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...

In cystic fibrosis (CF) airway epithelial sodium absorption is increased 2-3 fold. Since sodium absorption is inhibited by the sodium channel blocker amiloride, our aim was to assess its therapeutic benefit in cystic fibrosis. A randomized, double-blind, placebo-controlled, cross-over trial of nebulized amiloride was performed in 23 patients with cystic fibrosis. Amiloride or placebo was admini...

The inhibition of short-circuit current (Isc) in isolated frog skin and the induction of surface potentials in lipid bilayer membranes produced by the diuretic drug amiloride and a number of its chemical analogues was studied. The major conclusions of our study are: (a) The charged form of amiloride is the biologically active species. (b) Both the magnitude of Isc and the amiloride inhibitory e...

Aldosterone has long been known to control water and electrolyte balance by acting on mineralocorticoid receptors in kidney. However, recent studies demonstrated the presence of these receptors in nonclassical locations, including the cardiovascular system. We tested the hypothesis whether endothelial cells respond to aldosterone with changes in cell volume, a measure for ion-mediated water mov...