Characterization of bovine neutrophil beta2-adrenergic receptor function.
This study compares bovine leukocyte beta-adrenergic receptor densities to that of the rat, demonstrates for the first time a functional beta(2)-adrenergic receptor signaling pathway in steer neutrophils, and investigates the effect of an inflammatory stimulus on that signaling pathway. The beta(1)-/beta(2)-adrenergic antagonist ([3H])CGP-12177 demonstrated that rat lymphocyte specific binding-site density was highest, followed by steer and dairy cow lymphocytes, and lastly steer and dairy cow neutrophils. The beta(2)-adrenergic agonist terbutaline stimulated steer neutrophil adenosine 3,5-cyclic monophosphate (cAMP) production, an effect increased by inclusion of > or = 1 x 10(-8) M phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C. Both terbutaline and the nonselective phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) independently decreased steer neutrophil superoxide anion production in a concentration-dependent manner, with 1 x 10(-4) M IBMX enhancing both the potency and efficacy of the terbutaline effect (up to 74% reduction in superoxide anion production). Superoxide anion production was also reduced by the synthetic cAMP analog 8-bromo-cAMP, which increased the potency of the IBMX effect on superoxide anion production. Taken together, these data demonstrate the presence of a beta(2)-adrenergic receptor signaling pathway in bovine neutrophils much like that described in other animal species, as well as the potential for an inflammatory stimulus to alter its function.
LaBranche
T P
TP
Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061-0442, USA.
Ehrich
M F
MF
Eyre
P
P
D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D009504:Neutrophils / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D015398:Signal Transduction; D013481:Superoxides / Q000032:analysis*; D013726:Terbutaline / Q000494:pharmacology*
D058666:Adrenergic beta-2 Receptor Agonists; D018343:Receptors, Adrenergic, beta-2; D013481:Superoxides; D000242:Cyclic AMP; D013726:Terbutaline