Connective Tissue Research, 49:416–425, 2008 Copyright c  Informa Healthcare USA, Inc. ISSN: 0300-8207 print / 1607-8438 online DOI: 10.1080/03008200802324949 Transient Increase with Strenuous Exercise of Plasma Levels of Glycosaminoglycans in Humans and Horses Alberto Calatroni and Angela Avenoso Department of Biochemical, Physiological and Nutritional Sciences, Faculty of Medicine, University of Messina, Messina, Italy Alida M. Ferlazzo Department of Morphology, Biochemistry, Physiology and Animal Production, Faculty of Veterinary Medicine, University of Messina, Messina, Italy Arno Lindner Arbeitsgruppe Pferd, J¨ ulich, Germany Giuseppe M. Campo Department of Biochemical, Physiological and Nutritional Sciences, Faculty of Medicine, University of Messina, Messina, Italy Plasma glycosaminoglycans (GAGs) were isolated and purified by chromatographic procedures in healthy humans and horses before and after physical exercise. A weak anion exchange resin was used to separate polyanions. Humans exercised on a cycloergometer, while horses were exercised on a treadmill and in show jumping competition. Some GAGs were isolated from untreated plasma and operationally defined as native proteoglycans (PGs), while the total GAG amount was isolated from mild alkali treated plasma. Plasma GAG concentrations in terms of galactosamine and galactose, the respective components of the cartilage polysaccharides chondroitin sulphate and keratan sulphate, significantly increased only when the subject was exercised intensively, in both humans and horses. Only native PGs fraction contributed to GAG levels changes. The increases were transient, since preexercise values were reached in 30 min in horses. These changes with exercise are suggested to be a tool to measure the effect of physical exercise on cartilage PG metabolism. Keywords Proteoglycans, Glycosaminoglycans, Intensive Exercise, Plasma Address correspondence to Alberto Calatroni, PhD, Department of Biochemical, Physiological and Nutritional Sciences of the University of Messina, Policlinico Universitario, Torre Biologica, Via Consolare Valeria, I-98125 Messina, Italy. E-mail: alberto.calatroni@unime.it INTRODUCTION The concentration in plasma of acid glycosaminoglycans (GAG) [1, 2], sulphated polysaccharides that are usually covalently linked to a protein core to give proteoglycans (PGs) [3], is fairly constant in healthy mammals [4]. It has been reported to be significantly higher than sedentary control in trained humans [5, 6] and horses [7]. Furthermore, exercise affects plasma levels of nonsulphated acid polysaccharide hyaluronan (HYA) in humans [8], while serum GAG keratan sulphate (KS) concentration is reported to show no statistically significant differences in marathon runners after a marathon [9], an increase in humans after exercise [10], and a transient increase following training in horses [11]. Plasma GAGs may originate in peripheral connective tissue, such as cartilage and tendon, and may be secreted by blood cells [12] and by blood vessel cells [13]. In humans [1, 14] and in animals [4], the main GAG component of the circulating GAG mixture is galactosamine-containing chondroitin sulphate (CS), while glucosamine-containing KS and heparan sulphate (HS) are minor components. In addition, a very low concentration of unsulphated HYA was found [15] originating in peripheral connective tissues. In plasma GAGs are interacting with proteins, so that GAG total recovery is possible only following protein enzymic digestion or by mild alkaline treatment, releasing carbohydrate chains from O-glycosidic protein-carbohydrate linkages [16]. In this research alkaline treatment was used to measure total 416