Dexamethasone attenuates acute macromolecular efflux increase evoked by smokeless tobacco extract

The purpose of this study was to determine whether dexamethasone attenuates the acute increase in macromolecular efflux from the oral mucosa elicited by an aqueous extract of smokeless tobacco (STE) in vivo, and, if so, wheth er this response is specific. Using intravital microscopy, we found that 20 -min suffusion of STE elicited significant, concentration-related leaky sit e formation and an increase in clearance of fluorescein isothiocyanate-labe led dextran (FITC-dextran; mol mass 70 kDa) from the in situ hamster cheek pouch (P < 0.05). This response was significantly attenuated by dexamethaso ne (10 mg/kg iv). Dexamethasone also attenuated the bradykinin-induced leak y site formation and the increase in clearance of FITC-dextran from the che ek pouch. However; it had no significant effects on adenosine induced respo nses. Dexamethasone had no significant effects on baseline arteriolar diame ter and on bradykinin-induced vasodilation in the cheek pouch. Collectively , these data indicate that dexamethasone attenuates, in a specific fashion, the acute increase in macromolecular efflux from the in situ oral mucosa e voked by short-term suffusion of STE. We suggest that corticosteroids mitig ate acute oral mucosa inflammation elicited by smokeless tobacco.