B1 kinin receptor activity in pigs is associated with pre-existing infection.

Abstract Bradykinin (BK) and related kinins are potent inflammatory mediators produced during acute and chronic inflammation. The effects of these kinins are mediated via the stimulation of either a B 2 or a B 1 receptor. The B 1 receptor is not normally present but its expression can be induced within 4 h by a variety of noxious stimuli, specifically, Gram -negative bacteria or bacterial lipopolysaccharide (LPS) given to healthy animals. This study compared the cardiovascular response of healthy pigs and pigs diagnosed with a pre-existing spontaneously acquired infection to BK, a B 2 receptor agonist, and des-Arg 9 –BK, a B 1 receptor agonist. Eighty-eight percent of the animals diagnosed with an established infection based on a standardized clinical evaluation demonstrated increased sensitivity and responsiveness to des-Arg 9 –BK but normal responsiveness to BK and acetylcholine. In contrast, only 15% of healthy animals showed elevated responses to des-Arg 9 –BK. The response to des-Arg 9 –BK and BK in each group was characterised as B 1 and B 2 , respectively, using the selective B 1 and B 2 antagonists Lys 0 –Leu 8 –des-Arg 9 –BK and Hoe 140, respectively. This study demonstrates the existence and function of the B 1 receptor in animals with a previously acquired infection. These observations lend validity to animal experiments with LPS infusion in order to model bacterial inflammation.