Effects of 2,4-dinitrophenol amylobarbitone and certain other drugs on the rate of oxygen consumption and force of contraction of isolated curarized diaphragm muscle of the rat

Antimicrobial agent triclosan is a proton ionophore uncoupler of mitochondria in living rat and human mast cells and in primary human keratinocytes

Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non-cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL-2H3), and in this study, we replicate this finding in human mast cells (HMC-1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL-2H3 cells in glucose-free, galactose-containing media (95% confidence interval EC50 = 7.5-9.7 µm), without causing cytotoxicity. Using these same glucose-free conditions, 15 µm TCS dampens RBL-2H3 degranulation by 40%. The same ATP disruption was found with human HMC-1.2 cells (EC50 4.2-13.7 µm), NIH-3 T3 mouse fibroblasts (EC50 4.8-7.4 µm) and primary human keratinocytes (EC50 3.0-4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL-2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3-chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS-methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non-cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin-stimulated degranulation of RBL-2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd.

Effects of some S-alkylthiouroniums and related compounds on the osmotic fragility and the membrane expansion of human erythrocytes

1 Changes in the osmotic fragility and critical haemolytic volume of human erythrocytes produced by S-n-decylthiouronium (S-10) and related compounds have been studied. 2 S-10 had a biphasic action on osmotic fragility, protecting erythrocytes against lysis in low concentrations but producing lysis in a concentration of 1 mM or higher. 3 Some lower homologues of S-10 also protected erythrocytes against osmotic lysis, the degree of protection depending on the length of the alkyl chain. 4 Critical haemolytic volume was increased by antihaemolytic concentrations of procaine and chlorpromazine but not by antihaemolytic concentrations of S-10 and related amidines. 5 It is concluded that S-10 and its near homologues penetrate and stabilize erythrocyte membranes, potency increasing with the number of methylene groups in the side-chain up to about ten. The stabilization produced by S-10 apparently differs from that produced by many other lipid-soluble depressant drugs. It may be related to a drug-induced change in the ionic permeability of the membrane.