Effect of rolipram and dibutyryl cyclic AMP on resequestration of cytosolic calcium in FMLP-activated human neutrophils.
1. We have investigated the effects of the selective phosphodiesterase (PDE) type 4 inhibitor, rolipram (0.01-1 microM) on cytosolic Ca2+ fluxes in FMLP-activated human neutrophils, as well as on superoxide production by, and release of elastase from, these cells. 2. Cytosolic Ca2+ fluxes were measured by use of fura-2 spectrofluorimetry in combination with a radiometric procedure that enables distinction between net efflux and influx of the cation. Superoxide production and elastase release were measured by lucigenin-enhanced chemiluminescence and a colorimetric procedure, respectively. 3. Pretreatment of neutrophils with rolipram did not affect the FMLP-activated release of Ca2+ from intracellular stores, but was associated with dose-related acceleration of the rate of decline in fura-2 fluorescence and with decreased efflux, as well as store-operated influx of 45Ca2+, indicative of enhancement of resequestration of the cation by the endo-membrane Ca2+-ATPase. 4. Inhibition of superoxide production and elastase release was observed at concentrations of rolipram which accelerated the clearance of Ca2+ from the cytosol of FMLP-activated neutrophils. 5. These effects of rolipram on FMLP-activated Ca2+ fluxes, superoxide generation and elastase release were mimicked by pretreatment of neutrophils with dibutyryl cyclic AMP (0.5-4 mM), while theophylline (10-150 microM), a non-specific PDE inhibitor, as well as the beta2-agonist, salbutamol, were less effective. 6. We conclude that rolipram deactivates FMLP-stimulated human neutrophils by enhancement of cyclic AMP-dependent resequestration of cytosolic Ca2+.
Anderson
R
R
Department of Immunology, University of Pretoria, South Africa.
Goolam Mahomed
A
A
Theron
A J
AJ
Ramafi
G
G
Feldman
C
C
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D000420:Albuterol / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D003600:Cytosol / Q000378:metabolism*; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D066298:In Vitro Techniques; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D011760:Pyrrolidinones / Q000494:pharmacology*; D020889:Rolipram; D013481:Superoxides / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology
D000318:Adrenergic beta-Agonists; D002132:Calcium Radioisotopes; D005456:Fluorescent Dyes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003994:Bucladesine; D013806:Theophylline; D020889:Rolipram; D000420:Albuterol; D002118:Calcium; D016257:Fura-2