text: To study the mechanism underlying this phenomenon, the effects of the nonselective << beta-adrenoceptor >> antagonists propranolol [no intrinsic sympathomimetic activity (ISA)], alprenolol (weak ISA) and [[ mepindolol ]] (strong ISA) on lymphocyte beta 2-adrenoceptor density--assessed by (+/-)-[125I]-iodocyanopindolol (ICYP) binding--and plasma renin activity (PRA) were investigated in male healthy volunteers aged 23-35 years.