As an essential electrolyte for the human body, potassium ion (K+) plays many physiological roles in living cells, so rapid and accurate determination of serum K+ is great significance. In this work, we developed a solid-contact ion-selective electrode (SC-ISE) using MoS2/Fe3O4 composites as ion-to-electron transducer to determine K+. The potential response measurement MoS2/Fe3O4/K+-ISE shows N...

Active ion (NaCl) transport across isolated frog skin is discussed in relation to sodium and potassium composition and to O3 consumption of skin. A distinction is made between processes in skin related to "unidirectional active ion transport" and processes related to "maintenance electrolyte equilibrium;" i.e., ionic composition of skin. Several metabolic inhibitors were found that could be use...

Under many different conditions activated plasma membrane ion channels give rise to changes in the extracellular concentration of the permeant ion(s). The magnitude and duration of these changes are dependent on the electrochemical driving force(s) on the permeant ion(s) as well as conductance, open time, and channel density. We have modeled the change in the extracellular [K+] due to efflux th...

The ability of biological ion channels to conduct selected ions across cell membranes is critical for the survival of both animal and bacterial cells. Numerous investigations of ion selectivity have been conducted over more than 50 years, yet the mechanisms whereby the channels select certain ions and reject others are not well understood. Here we report a new application of Jarzynski's Equalit...

We employ the entire experimentally determined protein structure for the KcsA potassium channel from Streptomyces lividans in molecular dynamics calculations to observe hydrated channel protein structure, ion solvation, selectivity, multiple ion configurations, and diffusion. Free energy perturbation calculations display a significant ion discrimination of ;9 kT in favor of the larger K ion. Th...

Active ion (NaCl) transport across isolated frog skin is discussed in relation to sodium and potassium composition and to O(2) consumption of skin. A distinction is made between processes in skin related to "unidirectional active ion transport" and processes related to "maintenance electrolyte equilibrium;" i.e., ionic composition of skin. Several metabolic inhibitors were found that could be u...

Ultrasonic velocities in solution of tetrabutylammonium bromide (TBAB) in 10, 20 and 30 %w/w N, N– dimethylformamide (DMF)-water mixtures were measured at 303 K, 308 K and 313 K by using the pulse echo overlap method at a frequency of 3 MHz. The ultrasonic velocity, density, and viscosity were used to calculate the adiabatic compressibility, apparent molal compressibility, apparent molal volume...

I(H) pacemaker channels carry a mixed monovalent cation current that, under physiological ion gradients, reverses at approximately -34 mV, reflecting a 4:1 selectivity for K over Na. However, I(H) channels display anomalous behavior with respect to permeant ions such that (a) open channels do not exhibit the outward rectification anticipated assuming independence; (b) gating and selectivity are...