In everted vesicles of Escherichia coli, delta pH caused by H+ efflux through the Na+/H+ antiporter was measured by using a fluorescent dye. Amiloride inhibited the activity of the Na+/H+ antiporter. Kinetic studies showed that amiloride competed with Na+. The inhibition constant of 40 microM was obtained.

High resistance epithelia express on their apical side an amiloride-sensitive sodium channel that controls sodium reabsorption. A cDNA was found to encode a 1,420-amino acid long polypeptide with no signal sequence, a putative transmembrane segment, and three predicted amphipathic alpha helices. A corresponding 5.2-kb mRNA was detected in Xenopus laevis kidney, intestine, and oocytes, with weak...

Extracellular ATP regulates a variety of functions in epithelial tissues by activating the membrane P2-receptor. The purpose of this study was to investigate the autocrine/paracrine regulation by luminal ATP of electrogenic amiloride-sensitive Na(+) absorption in the distal colon from guinea pigs treated with aldosterone by measuring the amiloride-sensitive short-circuit current (I(sc)) and (22...

Amiloride, a Na+ channel blocker, and frusemide, an inhibitor of the Na+/K+/2Cl- co-transporter on the basolateral surface of airway epithelial cells, have the potential to affect water transport across the airway epithelium. As isocapnic hyperventilation challenge (ISH) with dry air may provoke airway narrowing in asthmatic subjects by dehydrating the airways, inhaled amiloride and frusemide m...

The proximal duodenal mucosa secretes HCO that serves to protect the epithelium from injury. In isolated human duodenal enterocytes in vitro, multiple luminal membrane proteins are involved in acid/base transport. We postulated that one or more isoforms of the Na(+)/H(+) exchanger (NHE) family is located on the apical surface of human duodenal mucosal epithelial cells and thereby contributes to...

We have previously characterized in Chinese hamster lung fibroblasts a growth factor activatable and amiloride-sensitive Na+/H+ antiport (Pouysségur, J., Chambard, J. C., Franchi, A., Paris, S., and Van Obberghen-Schilling, E. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 3935-3939). In this report, we compared the affinity of 28 analogs of amiloride for inhibition of the Na+/H+ antiport and inhib...

To determine Na+/H+ exchange in lamprey erythrocyte membranes, the cells were acidified to pH(i) 6.0 using the K+/H+ ionophore nigericin. Incubation of acidified erythrocytes in a NaCl medium at pH 8.0 caused a considerable rise in 22Na+ influx and H+ efflux during the first 1 min of exposure. In addition, exposure of acidified red cells to NaCl medium was associated with rapid elevation of int...

IN THE CRYSTAL OF THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(3,5-diamino-6-chloro-pyrazin-2-ylcarbon-yl)guanidinium chloride methanol disolvate], C(6)H(9)ClN(7)O(+)·Cl(-)·2CH(3)OH , the components are connected by N-H⋯N, N-H⋯Cl, N-H⋯O, O-H⋯Cl and O-H⋯O hydrogen bonds into a three-dimensional network. The dihedral angle between the aromatic ring and the guanidine residue is 6.0 (2)°.