Enzyme immunoassay of a beta-adrenergic agent using beta-galactosidase as label

Antisera against tetrahydronaphthalenols, which are conformationally rigid derivatives of adrenergic catecholamine, were produced in rabbits immunized with trans-5-amino-6-hydroxy-2-isopropylamino-1,2,3,4-tetrahydronaphthalene-1 -ol (I) conjugated to succinylated bovine serum albumin at the C5 position on the tetralin ring. Antisera were screened by immunodiffusion and further characterized by passive hemagglutination assay using erythrocytes sensitized with trans-I-ovalbumin conjugate and by enzyme immunoassay using trans-I-beta-galactosidase conjugate. Cross-reactivity studies indicated that the antiserum was highly specific for the tetralin structure and for substitution at the C2 position. The antiserum also selectively discriminated the stereoisomers about the C1-C2 bond. The anti-trans-I serum was used to develop EIA for trans-5-hydroxymethyl-6-hydroxy-2-isopropylamino-1,2,3,4-tetrahydronapht halene- 1-ol (IIb), which exhibited strong beta-stimulating activity fairly selective to tracheal muscle, since it recognized trans-IIb to the same degree as trans-I. The assay could detect as little as 100 pg of this compound. The mean recovery of trans-IIb added to plasma was 105%, and values for plasma trans-IIb determined by this immunoassay correlated well with those determined by gas chromatography-mass spectrometry.