Abstract: A method for the rapid estimation of hyperplastic and hypertrophic changes in animal airways is an assay which specifically measures acidic and neutral mucoproteins in a linear fashion from 0.5 to at least 10 .mu.g. The assay comprises exposure of a test animal to a suspected metaplastic inducer, removal of the lungs, homogenization in an appropriately buffered solution containing reducing agents and protease inhibitors; removal of particulate matter; and size-fractionation of the SDS treated soluble extract. The high molecular weight material is immobilized and stained for either acidic or neutral mucosubstances and the specific staining is quantitated. The changes observed are consistent with those seen in histological sections of the exposed tissues.

Abstract: A CHO-K1 cell line stably expressing a recombinant full-length human PDE IVa (rhPDEIVa) enzyme was established under hygromycin B selection. Inhibition of the expressed PDE IVa activity by selective PDE IV inhibitors was evaluated. The rank order of potencies of the inhibitors in elevating cAMP in the whole-cell assay was quite different from that on the soluble enzyme. The whole-cell rank order of potencies was also maintained when PKA activity ratios were measured in place of cAMP levels. When inhibition of soluble PDE IVa activity was examined in the presence of 100 mM MgCl.sub.2, the rank order of potencies of the inhibitors mirrored that obtained for the whole-cell assays (both cAMP and PKA). The observed "high-affinity" conformation of the enzyme was not dependent upon a specific cation or anion.