Veterinary Research Communications, 29(Suppl. 2) (2005) 273–275 DOI: 10.1007/s11259-005-0060-y C  Springer 2005 Effects of Inflammation upon β-adrenoceptor Concentrations in the Common Digital Artery of the Horse: An in vitro Study R. Barbero ∗ , P. Badino, B. Cuniberti, G. Magistris, R. Odore, S. Pagliasso, C. Girardi and G. Re Department of Animal Pathology, Division of Pharmacology & Toxicology, University of Torino, Italy ∗ Correspondence: E-mail: raffaella.barbero@unito.it Barbero, R., Badino, P., Cuniberti, B., Magistris, G., Odore, R., Pagliasso, S., Girardi, C. and Re, G., 2005. Effects of inflammation upon β-adrenoceptor concentrations in the common digital artery of the horse: An in vitro study. Veterinary Research Communications, 29(Suppl. 2), 273–275 Keywords: β-adrenergic receptors, common digital artery, horse, inflammation Abbreviations: β-AR, β-Adrenergic Receptor; PGE 2 , Prostaglandin E 2 ; COX, Cyclooxygenase; NSAIDs, Non-Steroidal Anti-Inflammatory Drugs; LPS, Lipopolysaccharide; PBS, Phosphate Buffer Solution INTRODUCTION NSAIDs exert their pharmacological action via inhibition of the COX enzyme. COX cat- alyzes the synthesis of inflammatory cytokines (prostaglandins, thromboxanes, and prosta- cyclins) from arachidonic acid (Jackson-Roberts II and Morrow, 2001). COX exists as at least two isoforms: the COX-1 isoform, the constitutive form of the enzyme expressed by cells, responsible for the biosynthesis of prostaglandins with protective functions in differ- ent tissues; and the COX-2 isoform, an inducible form of the enzyme that is synthesized during inflammation (Vane et al., 1998). The effects of inflammation on the expression and functionality of the β-AR population have recently been demonstrated (Pascual et al., 2001). Evidence for the down-regulation and desensitization of β-ARs induced by selected cytokines (e.g., IL-6; α-TNF) has been reported. These effects seem to be mediated by activation of the COX-2 isoform, with a consequent increase in PGE 2 levels. Among the pathogenic factors of equine musculoskeletal disorders (e.g., laminitis), inflammation may play a crucial role, particularly concerning possible vascular alterations (Rodgerson et al., 2001). The aim of the present study was to investigate the in vitro effects of COX-2 activa- tion on the β-AR concentration of the equine digital artery. The β-AR concentrations were measured in vascular smooth muscle under basal conditions and after exposure to a bacterial toxin (Escherichia coli lipopolysaccharide or LPS) producing an inflammatory process. MATERIALS AND METHODS Samples of common digital artery were collected from healthy adult horses regularly slaugh- tered in an authorized abattoir (“Italmacello” Pianezza, Turin). Immediately after death, 273