Alterations in buccal mucosal endothelin-1 and nitric oxide synthase with chronic alcohol ingestion.

Endothelin-1 (ET-1) and nitric oxide are emerging key mediators in the maintenance of mucosal homeostasis, but little is known about these substances in soft oral tissue with alcohol abuse. Hence, we examined the expression of ET-1 and activity of the constitutive nitric oxide synthase (NOS) in buccal mucosa of rats subjected to chronic ethanol diet. The immunometric assays revealed the buccal mucosal level of ET-1 in the controls at 40.2 pg/mg protein and showed a 4.1-fold increase with alcohol diet to 166.2 pg/mg protein. The NOS assays established that comparing to the controls, the alcohol diet group exhibited a 57% decrease in buccal mucosal NOS activity. Moreover, the expression of ET-1 showed an inverse correlation (r = -0.75) with the extent of the induced changes in NOS. The results suggest that an increase in vasoconstrictive ET-1 levels combined with a loss of compensatory action by the constitutive NOS may be responsible for the weakening of oral mucosal defenses in alcoholics.