This study will examine the relationship between adrenergic hypersensitivity, the pharmacokinetics of B-adrenergic antagonists, and changes in B-adrenergic receptors following abrupt B-adrenergic antagonist withdrawal. Kinetics of B-receptors (changes in density and/or affinity) on human lymphocytes before, during, and after propranolol and nadolol administration and the pharmacokinetics.