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Updated: Oct 17, 2026

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples
Published on: May 21, 2021
beta-Adrenoceptor stimulation up-regulates phosphodiesterase 4 activity and reduces prostaglandin E2-inhibitory
J L Ortiz1, F J Dasí, J Cortijo
1Departament de Farmacologia, Facultat de Medicina i Odontologia, Universitat de València, Spain. jose.l.ortiz@uv.es
Abstract:
Human neutrophils were treated for 4 h with a combination of salbutamol (1 microM), a beta2-adrenoceptor agonist, and rolipram (30 microM), a selective phosphodiesterase 4 inhibitor, to investigate whether this treatment produces up-regulation of phosphodiesterase activity with functional consequences. Anion-exchange chromatography coupled with the use of selective activators and inhibitors demonstrated that a phosphodiesterase activity with characteristics of the isoenzyme type 4 was increased in drug-treated cells. Kinetic analysis showed a approximately 1.5-fold increase in Vmax without alteration of Km values. The augmented phosphodiesterase activity in drug-treated cells was abolished by actinomycin D. Cyclic AMP content in drug-treated cells was higher than resting values (27.28+/-2.79 pmol/10(6) cells vs. 0.34+/-0.03 pmol/10(6) cells). Reverse transcriptase-polymerase chain reaction showed increased expression of mRNA transcripts for PDE4B and PDE4A in drug-treated cells. Functionally, up-regulation of phosphodiesterase 4 reduced the inhibition by prostaglandin E2 of zymosan-induced superoxide generation.
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