Respiratory-burst stimulants desensitize beta-2 adrenoceptors on human polymorphonuclear leukocytes
Vago, T.; Norbiato, G.; Baldi, G.; Chebat, E.; Bertora, P.; Bevilacqua, M.
International Journal of Tissue Reactions 12(1): 53-58
1990
ISSN/ISBN: 0250-0868 PMID: 1974545 Document Number: 349012
We investigated the effect of respiratory-burst stimulants on beta-2 adrenoceptors in human polymorphonuclear leukocytes (PMNL). Pre-incubation of PMNL with these substances did not affect the number or affinity of the receptors but desensitized them, as shown by the "right-shift" in (-)-isoproterenol competition isotherms. H-7, an established protein kinase C inhibitor, and nimesulide, a new putative inhibitor of this enzyme, blunted both superoxide anion production and beta-2 adrenoceptor desensitization. A positive correlation was found between superoxide anion generation and the "right-shift" in isoproterenol competition isotherm (r = 0.92; p less than 0.01). Desensitization of beta-2 adrenoceptors was not due to superoxide anions per se since incubation of PMNL with superoxide anion scavengers (superoxide dismutase and catalase) did not modify the results.