RT Journal Article
SR Electronic
T1 A highly-selective chloride microelectrode based on a mercuracarborand anion carrier
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 629691
DO 10.1101/629691
A1 Marino DiFranco
A1 Marbella Quinonez
A1 Rafal M. Dziedzic
A1 Alexander M. Spokoyny
A1 Stephen C. Cannon
YR 2019
UL http://biorxiv.org/content/early/2019/05/07/629691.abstract
AB The chloride gradient plays an important role in regulating cell volume, membrane potential, pH, secretion, and the reversal potential of inhibitory GABAA receptors. Measurement of intracellular chloride activity, , using liquid membrane ion-selective microelectrodes (ISM), however, has been limited by the physiochemical properties of Cl ionophores which have caused poor stability, drift, sluggish response times, and interference from other biologically relevant anions. Most importantly, intracellular HCO3− may be up to 4 times more abundant than Cl− (e.g. skeletal muscle) which places severe constraints on the required selectivity of a Cl – sensing ISM.Previously, a sensitive and highly-selective Cl sensor was developed in a polymeric membrane electrode (Badr et al. 1999) using a trinuclear Hg(II) complex containing carborane-based ligands, [9]-mercuracarborand-3, or MC3 for short. Here, we have adapted the use of the MC3 anion carrier in a liquid membrane ion-selective microelectrode and show the MC3-ISM has a linear Nernstian response over a wide range of aCl (0.1 mM to 100 mM), is highly selective for Cl over other biological anions or inhibitors of Cl transport, and has a response time of less than 5 sec. Importantly, over the physiological range of aCl (1 mM to 100 mM) the potentiometric response of the MC3-ISM is insensitive to HCO3− or changes in pH. Finally, we demonstrate the biological application of an MC3-ISM by measuring intracellular aCl, and the response to an external Cl-free challenge, for an isolated skeletal muscle fiber.9-ACA9-anthracenecarboxylic acidBMTbumetanideISMion selective microelectrodeMC3[9]mercuracarborand-3NPOE2-nitrophenyl octyl etherTDMACtridodecylmethyl ammonium chloride