Diphenhydramine transport by pH-dependent tertiary amine transport system in Caco-2 cells

Abstract

Substrate specificity and pH dependence of the transport system for diphenhydramine were investigated in Caco-2 cell monolayers. Diphenhydramine uptake was not affected by any typical substrate for the renal organic cation transport system except procainamide. Along with procainamide, tertiary amine compounds with N-dimethyl or N-diethyl moieties in their structures inhibited the diphenhydramine uptake. Moreover, accumulation of diphenhydramine was stimulated by preloading the Caco-2 cells with these tertiary amines (trans-stimulation effect), indicating the existence of the specific transport system for tertiary amines with N-dimethyl or N-diethyl moieties. Efflux of diphenhydramine from monolayers was enhanced by medium acidification. In addition, intracellular acidification resulted in marked stimulation of diphenhydramine accumulation. ATP depletion of the cells caused an enhancement of diphenhydramine accumulation, suggesting the involvement of an active secretory pathway. However, P-glycoprotein did not mediate the diphenhydramine transport. These findings indicate that a novel pH-dependent tertiary amine transport system that recognizes N-dimethyl or N-diethyl moieties is involved in diphenhydramine transport in Caco-2 cells.

Transport Mechanisms of Nicotine across the Human Intestinal Epithelial Cell Line Caco-2

“…Previously, we reported that transport of tertiary amines was mediated by the pH-dependent specific transport system in Caco-2 cells (Mizuuchi et al, 1999(Mizuuchi et al, , 2000a and also in the brush-border membrane vesicles (Katsura et al, 2000). Our previous findings also suggested that the transport system for tertiary amines would specifically recognize the N,Ndimethyl or N,N-diethyl moieties in tertiary amine compounds (Mizuuchi et al, 2000a).…”

“…Our previous findings also suggested that the transport system for tertiary amines would specifically recognize the N,Ndimethyl or N,N-diethyl moieties in tertiary amine compounds (Mizuuchi et al, 2000a). In contrast, nicotine consists of an N-methyl pyrrolidine ring and, therefore, a cyclic tertiary amine.…”

“…The involvement of P-glycoprotein (Hsing et al, 1992;Hunter et al, 1993a,b) and some members of the amphiphilic solute facilitator (ASF) family such as OCT1, OCT2, or extraneuronal monoamine transporter (EMT) (Bleasby et al, 2000;Martel et al, 2001) have been reported. We previously demonstrated that diphenhydramine, an antihistamine, was transported across Caco-2 cell monolayers by H ϩ -coupled specific transport systems that exist in both the apical and basolateral membranes (Mizuuchi et al, 1999(Mizuuchi et al, , 2000aKatsura et al, 2000). The direction of the transepithelial transport for tertiary amines such as diphenhydramine corresponded to intestinal secretion, indicating the existence of a secretory pathway for tertiary amines.…”

Coexistence of Passive and Proton Antiporter-Mediated Processes in Nicotine Transport at the Mouse Blood–Brain Barrier

“…An analogous nicotine/proton antiporter has also been characterized in kidney tubules, Caco-2, JAR, and LLC-PK1 cell lines (8,36,37). Many cationic organic drugs, such as clonidine, diphenhydramine, and MDMA, are similarly transported by a proton antiporter in Caco-2 cells (38)(39)(40). The trans-stimulation of the BBB transport of nicotine by diphenhydramine, naloxone, or tramadol suggests that they share the same transporter.…”

Clonidine Transport at the Mouse Blood—Brain Barrier by a New H+ Antiporter that Interacts with Addictive Drugs

“…However, these earlier studies provided no information on the molecular and/or functional identity of this transporter, as evidence regarding this was obtained only recently (Koepsell et al, 2007). The carrier-mediated transport of DPH, which could involve the clonidine BBB transporter, was suggested to be present at the BBB and to work as an H + antiporter in Caco-2 cells (Au-Yeung et al, 2006;Goldberg et al, 1987;Mizuuchi et al, 2000). An H + antiporter for oxycodone was recently found in immortalized rat brain endothelial cells, as was a similar antiporter for MDMA in Caco-2 cells (Kuwayama et al, 2008;Okura et al, 2008).…”