Drotaverine is considered an inhibitor of cyclic-39,59-nucleotidephophodiesterase (PDE) enzymes; however, published receptor binding data also support the potential L-type voltage-operated calcium channel (L-VOCC) blocking effect of drotaverine. Hence, in this work, we focus on the potential L-VOCC blocking effect of drotaverine by using L-VOCC-associated functional in vitro models. Accordingly, drotaverine and reference agents were tested on KCl-induced guinea pig tracheal contraction. Drotaverine, like the L-VOCC blockers nifedipine or diltiazem, inhibited the KCl-induced inward Ca 21 -induced contraction in a concentration-dependent fashion. The PDE inhibitor theophylline had no effect on the KCl-evoked contractions, indicating its lack of inhibition on inward Ca 21 flow.
Immunization with complex mixtures, like the human plasma resulted in the generation of cloned mAb libraries (PlasmaScan™ and QuantiPlasma™ libraries, with >1000 individual mAbs) reacting with a nonredundant set of antigenic epitopes. mAb proteomics refers to quasi-hypothesis-free profiling of plasma samples with nascent or cloned mAb libraries for the discovery of disease-specific biomarkers. Once mAbs with biomarker potential have been identified, the next task is the determination of cognate antigens recognized by the respective mAbs. To determine the cognate protein antigen corresponding to each individual mAbs in the cloned mAb libraries, we have separated human plasma by consecutive steps of desalting and various chromatography procedures. The process resulted in 783 fractions, which we termed "Analyte Library" (AL). The AL represents the human plasma proteome in relatively low-protein complexity fractions. Here, to determine the utility of the AL, we selected ten plasma proteins and checked for their presence in the fractions. Among the ten cases, the distribution of four selected plasma proteins matched expectations, as these proteins were present only in a few fractions corresponding to their physical, chemical, and biochemical properties. However, in six cases, we observed "smear" -like distribution or complete absence of the proteins, suggesting that protein-protein interactions or protein variants may alter the observed plasma distribution profiles. Nevertheless, we conclude that the AL is an efficient, high throughput tool to complement the mAb biomarker discovery process with cognate protein antigen identification for each mAbs.
Background: Drotaverine, a type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitor, blocks the degradation of 3’,5’-cyclic adenosine monophosphate. However, published receptor binding data showed that drotaverin also binds to the L-type voltage-operated calcium channel (L-VOCC). Based on these molecular mechanisms of action, a direct and indirect (by blocking the constrictor response) relaxant effect on airway smooth muscle can be predicted, which has not yet been assessed. Summary: Accordingly, drotaverine and reference agents were tested both on the histamine-, methacholine-, or KCl-induced contraction response and on precontracted guinea pig tracheal preparations. It was found that drotaverine not only relaxed the precontracted tracheal preparations but also decreased mediator-induced contraction. These effects of drotaverine were concentration dependent, with a significantly higher potency on the KCl-induced response, than on either the histamine or methacholine induced one. A similar result was noted for nifedipine. The PDE inhibitor, theophylline, also relaxed the precontracted preparations but was ineffective on the mediator-induced contraction in a physiologically relevant concentration range. Moreover, theophylline did not show selectivity and was the least potent relaxant among the 3 tested molecules. Key Message: These results show that drotaverine is a more potent airway smooth muscle relaxant molecule than theophylline. This enhanced potency on relaxation and inhibition of the constrictor response, at least partly, may be explained by the combined L-VOCC blocking and PDE inhibitory potential of drotaverine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.