ALPHA(1)-ADRENERGIC RECEPTOR ANTIBODIES IN PATIENTS WITH PRIMARY HYPERTENSION

Autoimmune mechanisms have been proposed to play a role in the pathoge nesis of primary (essential) hypertension. Autoantibodies against the alpha(1)-adrenergic receptor have been described in patients with mali gnant and secondary hypertension. To investigate the incidence of auto antibodies against the alpha(1)-adrenoceptor in patients with primary hypertension, we examined the immunoglobulin fractions of sera from 54 patients with primary hypertension and 26 normotensive control subjec ts for the presence of autoantibodies against the alpha(1)-sdrenocepto r. Sera from 24 patients (44%) and 3 subjects (12%) were positive. An epitope analysis of 16 autoantibody-positive immunoglobulin fractions revealed that in two thirds of the cases, the antibodies were directed against the first extracellular loop of the alpha(1)-adrenoceptor and in one third, against the second. The autoantibodies had a positive c hronotropic affect on isolated neonatal rat cardiomyocytes, an effect that was blocked by alpha(1)-adrenergic antagonists. Since the functio nal characteristics of the autoantibodies showed no desensitization ph enomena, they may play a role in elevating peripheral vascular resista nce and promoting cardiac hypertrophy in patients with primary hyperte nsion.