RT Journal Article SR Electronic T1 Neuromuscular Dysfunction in the Jejunum and Colon of Human Leukocyte Antigen B27 Transgenic Rats JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 60 OP 66 VO 293 IS 1 A1 Kalina Venkova A1 S. Terence Dunn A1 Adekunle M. Adesina A1 Beverley Greenwood-Van Meerveld YR 2000 UL http://jpet.aspetjournals.org/content/293/1/60.abstract AB HLA-B27 transgenic rats are a model of spontaneous gastrointestinal inflammation associated with expression of human leukocyte antigen (HLA) B27 and β2-microglobulin. Our goal was to investigate in vitro enteric nerve regulation and contractile activity in isolated longitudinal muscles from the jejunum and colon of HLA-B27 rats. Nontransgenic age-matched Fisher 344 rats were used as controls. Intestinal inflammation and tissue injury, quantified histologically and through tissue myeloperoxidase activity, were evident in both the jejunum and colon of HLA-B27 rats. Although resting tension and spontaneous activity of the jejunal and colonic muscles from HLA-B27 rats did not differ significantly from controls, responses to both enteric nerve stimulation or direct muscle activation were significantly inhibited. In muscles from HLA-B27 rats, electrical field stimulation (0.5 ms, 0.5–20 Hz) induced low-amplitude contractions (maximal reduction 60–65%) compared with respective controls. In the presence of atropine and guanethidine, nonadrenergic and noncholinergic contractile responses to higher frequencies of stimulation (8–20 Hz) were also of lower amplitude. These changes were accompanied by a shift in neurally mediated contractions from predominantly cholinergic in the jejunum and colon of Fisher 344 rats to predominantly nonadrenergic and noncholinergic in HLA-B27 rats. Furthermore, maximal contractions to carbachol or KCl depolarization were reduced (up to 2.7-fold) compared with respective controls. In the jejunum of HLA-B27 rats the EC50 level for carbachol was decreased. The data indicate that gastrointestinal inflammation induced by expression of HLA-B27 is associated with hypocontractility and inhibition of enteric cholinergic control of the longitudinal muscle in both the small and large intestine. The American Society for Pharmacology and Experimental Therapeutics