XXXX autoantibody to vasoactive intestinal peptide: increased incidence in muscular exercise.

@entity1 @entity3549
Specific autoantibodies to vasoactive intestinal peptide were present in plasma from 29.6% healthy @entity1 subjects who habitually performed muscular exercise, compared to 2.3% healthy subjects who did not. Saturation analysis of @entity3549 binding by the plasmas suggested the presence of 1 and 2 classes of autoantibodies in 5 and 3 high exercise subjects, respectively, distinguished by their equilibrium affinity constants (Ka). The mean Ka values for the high and low affinity autoantibody classes were, respectively, 1.3 x 10(8) M-1 and 0.8 x 10(7) M-1. These values are lower than the Ka range reported previously for tissue @entity3549 receptors (G. Rosselin. Peptides 7, Suppl. 1, 89, 1986) but are larger than the inverse Michaelis constant (1/Km) for @entity3549 -degrading proteases (T.N. Keltz, E. Straus, R.S. Yalow. Biochem. Biophys. Res. Commun. 92, 669, 1980). The autoantibodies may not interfere with @entity3549 -receptor binding but are potential inhibitors of the proteolytic inactivation of @entity3549 .
