Studies on cellular resilience and adaptation following acute and repetitive exposure to ozone in cultured human epithelial (HeLa) cells.

Ozone is used to treat several medical conditions, while the underlying mechanisms of action are sometimes poorly understood. In the current study, we exposed cultured human epithelial (HeLa) cells acutely and repeatedly to ozone and investigated the effects thereof on cell viability. The involvement of anti-apoptotic pathways in observed adaptive responses to ozone were investigated by employing the Akt inhibitor (-)-deguelin.

Phenoxybenzamine and benextramine, but not 4-diphenylacetoxy-N-[2-chloroethyl]piperidine hydrochloride, display irreversible noncompetitive antagonism at G protein-coupled receptors.

Many irreversible antagonists have been shown to inactivate G protein-coupled receptors (GPCRs) and used to study agonists and spare receptors. Presumably, they bind to primary (agonist) binding sites on the GPCR, although noncompetitive mechanisms of antagonism have been demonstrated but not thoroughly investigated. We studied noncompetitive antagonism by phenoxybenzamine and benextramine at alpha(2A)-adrenoceptors in stably transfected Chinese hamster ovary cells, benextramine and 4-diphenylacetoxy-N-[2-chloroethyl]piperidine hydrochloride (4-DAMP mustard) at endogenous muscarinic acetylcholine (mACh) receptors in human neuroblastoma SH-SY5Y cells, and benextramine at serotonin 5-HT(2A) receptors in stably transfected SH-SY5Y cells.