The influx of Cl- across isolated frog skin bathed on the outside by 0.8 mM NaCl is about 100 nmol cm-2 h-1, which is approximately twice the Cl- influx in intact animals. The influx consists of diffusion (1%), exchange diffusion (38%), and active transport (60%). About 80% of the influx is independent of Na+ in the outer bath and is also independent of concomitant inward movement of cations. C...

In voltage-gated cation channels, a recurrent pattern for mutations is the neutralization of positively charged residues in the voltage-sensing S4 transmembrane segments. These mutations cause dominant ion channelopathies affecting many tissues such as brain, heart, and skeletal muscle. Recent studies suggest that the pathogenesis of associated phenotypes is not limited to alterations in the ga...

Many large organic cations are potent blockers of K(+) channels and other cation-selective channels belonging to the P-region superfamily. However, the mechanism by which large hydrophobic cations enter and exit the narrow pores of these proteins is obscure. Previous work has shown that a conserved Lys residue in the DEKA locus of voltage-gated Na(+) channels is an important determinant of Na(+...

Kenneth Russell Thad Starner Perceptual Computing Section, The Media Laboratory, Massachusetts Institute of Technology Room E15-383, 20 Ames Street, Cambridge MA 02139, USA E-mail: [email protected], [email protected], [email protected] Alex Pentland Abstract Bulky head-mounted displays, data gloves, and severely limited movement have become synonymous with virtual environments. In this...

The substrate specificity of the avian renal organic cation exchanger was examined in isolated renal brush-border membrane vesicles. Endobiotic and xenobiotic organic cations (OCs) were tested at a concentration of 100 microM for cis-inhibition of 14C-tetraethylammonium (TEA)/H+ exchange and at 1 mM for trans-stimulation of 14C-TEA efflux. The xenobiotic cations amiloride, cimetidine, mepiperph...

We propose to detect isomorphisms of algebraic modular speci cations, by representing speci cations as diagrams over a category C0 of base speci cations and speci cation morphisms. We start with a formulation of modular speci cations as terms, which are interpreted as diagrams. This representation has the advantage of being more abstract, i.e. less dependent of one speci c construction than ter...