Lymphocytic beta-adrenergic receptors in X-linked muscular dystrophy

Lymphocytic beta-adrenoceptor levels, receptor binding affinity, lymphocytic basal and isoproterenol-stimulated cyclic AMP (cAMP) production and plasma catecholamine levels were studied in 49 patients with neuromuscular diseases and in 10 healthy subjects. Patients with X-linked muscular dystrophy (Duchenne, 13 patients; Becker, 4 patients) showed a significant reduction in lymphocytic beta-adrenoceptor densities (35.9 +/- 2.2 fmol/mg protein vs. 49.6 +/- 3.6 fmol/mg, controls; P less than 0.02), whereas the receptor levels for the patients with spinal muscular atrophy (15), polymyositis (10) and for Duchenne carriers (7) did not differ significantly from the corresponding levels for the control subjects. The reduction in the beta-adrenoceptor density was not correlated with the physical disability of the patients. Lymphocytic beta-adrenoceptor affinity (KD) and basal and isoproterenol-stimulated cAMP levels were all comparable to control subjects' values. Catecholamine levels showed mild inconsistent elevations in various patient groups. The results suggest that reduction in cellular beta-adrenoceptors is characteristic of X-linked muscular dystrophies. Its relationship to the basic gene defect is unknown.