In vitro inhibition of histamine metabolism in guinea pig lung by S-(-)-nicotine.
S-(-)-Nicotine competitively inhibits the metabolism of histamine to its N tau-methylated derivative in guinea pig lung homogenates. S-(-)-Nicotine exhibited a dissociation constant of the enzyme:inhibitor complex, Ki, of 9.4 X 10(-5) M compared with Km's for histamine and co-factor, S-adenosylmethionine, of 4.74 X 10(-5) M and 1.76 X 10(-5) M, respectively. This demonstrates the first reported involvement of nicotine in histaminergic mechanisms.