Date of Award


Degree Type


Degree Name

Doctor of Philosophy


1-Aminobenzotriazole (ABT) and its N-benzyl (BBT) and N-{dollar}\alpha{dollar}-methylbenzyl ({dollar}\alpha{dollar}MB) derivatives were compared as isozyme-selective, lung-selective (vs liver) mechanism-based inhibitors of P450 in guinea pigs 4 hr following i.v. administration. Monooxygenase activities selective for guinea pig orthologues of rabbit P450 1A1, 2B4 and 4B1 (1A1, 2Bx and 4Bx, respectively) were determined in pulmonary and hepatic microsomes. BBT and {dollar}\alpha{dollar}MB inactivated pulmonary P450 in an isozyme-selective manner. In non-induced and phenobarbital-induced animals the order of inactivation was 2Bx {dollar}>{dollar} 1A1 {dollar}>>>>{dollar} 4Bx whereas in {dollar}\beta{dollar}-naphthoflavone-induced animals {dollar}\alpha{dollar}MB specifically inhibited 2Bx. BBT and {dollar}\alpha{dollar}MB were also highly selective for the inactivation of pulmonary vs hepatic P450. In non-induced and induced animals at least one of the doses examined caused marked inactivation of pulmonary 2Bx ({dollar}>{dollar}80% with {dollar}\alpha{dollar}MB and 50-70% with BBT) without inhibiting any of the hepatic monooxygenase activities. In contrast, ABT displayed little isozyme-selectivity and little tissue-selectivity.;Guinea pig lung microsomes were found to convert arachidonic acid to two classes of P450-dependent metabolites, 16- through 20-hydroxyeicosatetraenoic acids ((16-20)-OH-AA) and epoxyeicosatrienoic acids (EETs). (16-20)-OH-AA formation was increased by {dollar}\beta{dollar}-naphthoflavone treatment. P450 2B selective inhibitors (metyrapone, SKF-525A and {dollar}\alpha{dollar}MB) as well as antibodies to rabbit P450 2B4 inhibited EETs formation by {dollar}>{dollar}85%-{dollar}>{dollar}95% with little effect on (16-20)-OH-AA formation. Neither a P450 1A selective inhibitor ({dollar}\alpha{dollar}-naphthoflavone) nor antibodies to rabbit P450 4B1 inhibited the formation of either class o{dollar}\sp-{dollar} metabolites. These data demonstrate that P450 2Bx is solely responsible for the metabolism of arachidonic acid to EETs in guinea pig lung and that a form of P450 other than 2Bx, 4Bx or 1A1, which is inducible by {dollar}\beta{dollar}-naphthoflavone, forms (16-20)-OH-AA.;Guinea pig kidney microsomoes also formed (16-20)-OH-AA and EETs. The formation of these metabolites was not affected by {dollar}\beta{dollar}-naphthoflavone induction or P450 1A1 inhibitors demonstrating that P450 1A1 also does not contribute to arachidonic acid metabolism in guinea pig kidney.;In summary, BBT and {dollar}\alpha{dollar}MB, at appropriate doses, are isozyme-selective/specific (P450 2Bx), lung-specific inhibitors of P450 in guinea pig in vivo. In guinea pig lung, P450 2Bx is responsible for the metabolism of arachidonic acid to EETs. Guinea pig P450 4Bx and 1A1 do not metabolize arachidonic acid.



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