Inactive renin release from the human arm vascular wall during upper arm occlusion: relation to beta-adrenoceptors

To investigate the extrarenal release of renin, plasma active renin (PAR) and plasma trypsin activatable or inactive renin (PIR) in blood taken simultaneously from bilateral median cubital veins were measured in seven normal men before and after occlusion of the right upper arm with a standard cuff inflated halfway between systolic and diastolic blood pressures for 15 min. After 15 min, both PAR (P less than 0.05) with PIR (P less than 0.01) increased significantly in occluded arms compared with 0 min. PIR rose significantly (P less than 0.01) in occluded arms compared with controls at 15 min, but PAR was unchanged. The same studies were repeated after pretreatment with oral doses of either 1 mg prazosin or 10 mg propranolol at 1600 h and 2400 h on the previous day and 1 hour before the experiment. After prazosin, both PAR (P less than 0.05) and PIR (P less than 0.01) in occluded arms increased significantly at 15 min compared with those at 0 min and PIR rose significantly (P less than 0.01) in occluded arms compared with controls at 15 min, as observed in the control studies. On the other hand, after propranolol, the significant increment of PAR in the occluded arms was abolished. Moreover, the significant difference of PIR between the occluded and the control arms at 15 min was also abolished. These results indicate that inactive renin may be present in the vascular wall of the arm and released into circulation by a stimulus such as arm occlusion by mechanisms related to beta-adrenoceptors.