title: The effect of propranolol on whole-body microvibrations during examination stress.
abstract: Whole-body microvibrations (MV) in three dimensions were measured in 51 volunteers, all medical students, 26 without and 25 with beta-receptor blockade (propranolol), immediately before a practical physiology examination and during the ensuing vacation. Propranolol impeded the increase in MV values in all three axes, significantly those in the z axis (vertical), the differences in MV values between the two measurements being minimal in the beta-receptor blocked group. On the other hand, propranolol enhanced MV in the x axis (anteroposterior) and the y axis (transverse), the y axis difference being significant only in females. Propranolol obviously relieves examination stress: the majority of candidates (52%) felt "quieter" in the examination with than in other similar situations without beta-receptor blockade. Propranolol was, however, without effect on the examination results. The rectified impulse in the z axis when related to body weight (Jz) correlates linearly with the calculated cardiac output. Propranolol, however, reduced cardiac output more than Jz, pointing to a Jz component non-sensitive to beta-receptor blockade. The part played by muscle tonus, mainly reflected in the y axis, thus remains unknown. The large and slow oscillations in the x and y axes, observed particularly in beta-receptor blocked females, might be attributed to diminution in standing ability.
mesh_terms: D000328:Adult; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D011433:Propranolol / Q000494:pharmacology*; D012737:Sex Factors; D013312:Stress, Physiological / Q000150:complications*; D014202:Tremor / Q000188:drug therapy* / Q000209:etiology; D014732:Vibration
chemical_list: D011433:Propranolol