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Int J Sports Med 1986; 07(3): 172-176
DOI: 10.1055/s-2008-1025757
© Georg Thieme Verlag Stuttgart · New York

Alpha-2-Adrenoreceptor Density on Intact Platelets and Adrenaline-Induced Platelet Aggregation in Endurance- and Nonendurance-Trained Subjects

M. Lehmann, K. Hasler, E. Bergdolt, J. Keul
  • Center of Internal Medicine, Department of Sports and Performance Medicine, University of Freiburg, Germany
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Publication Date:
14 March 2008 (online)

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Abstract

Alpha-2-adrenoreceptor density on intact platelets was evaluated in 17 sportsmen, 8 of whom were endurance-trained athletes. Receptor density was determined as being equivalent to 3H-Yohimbine, specifically bound on intact platelets. Adrenaline-induced aggregation of platelets in vitro was additionally ascertained. Bmax (maximal binding) and KD (dissociation constant) were significantly lower in endurance-trained athletes (148 fmol per 109 platelets, KD = 0.92 nmol) than in the nine nonendurance-trained individuals (284 fmol, KD = 1.79 P < 0.01), amounting to 89 receptors per cell (endurance-trained subjects) and 171 (nonendurance-trained subjects). No significant change of receptor density or affinity was observed subsequent to exhaustive exercise in the group of eight endurance-trained individuals. Bmax values and oxygen uptake capacity correlated negatively (r = -0.78, P < 0.001) and Bmax values and induced platelet aggregation in vitro positively (r = 0.79, P < 0.001). Data may indicate a reduced sensitivity of platelets in endurance-trained subjects.

Key words

alpha-2-adrenoreceptors - platelets - sportsmen

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