Organ specificity of induction of activating and inactivating enzymes by cigarette smoke and cigarette smoke condensate

Abstract

Inhalation of cigarette smoke specifically induces the rat lung and kidney aryl hydrocarbon hydroxylase (AHH) in less than 4 h. The epoxide hydratase (EH) and the glutathione S-transferase are not significantly modified by a similar treatment in any of the rat tissues. Compared to the kidney AHH, the lung hydroxylase is 3--4 times more sensitive to small concentrations of cigarette smoke and seems to have a longer biological half-life. In both tissues, the induced AHH presents the same in vitro sensitivity to various inhibitors as a polycyclic hydrocarbon induced AHH. In primary fetal rat liver cell culture, the cigarette smoke condensate fractions (CSCF) induce both the AHH and EH activity. Nevertheless, the AHH activity responds faster and to lower concentrations of CSCF than the EH activity. The liver cell culture constitutes a unique tool for a comparative study of the AHH and EH induction mechanism. Low concentration (10 muM) of benz(a)anthracene induces only the AHH activity while trans-stilbene oxide enhances selectively the EH activity. Appropriate concentrations of CSCF or of phenobarbital (PB) determine a parallel induction of both enzymes. The results are discussed on the basis of (a) the existence of specific mechanisms of AHH regulation in the lung and in the kidney and (b) the existence of coordinated or independent biochemical control of the AHH and EH activity.