Examination stress, platelet peripheral benzodiazepine binding sites, and plasma hormone levels.

The maximal binding capacity (Bmax) and the equilibrium dissociation constant (KD) values for [3H]PK 11195 binding to peripheral benzodiazepine binding sites were measured in the platelets of subjects immediately after examination stress and 10 days later, as well as in unstressed controls. Increased (52%; p less than 0.05) Bmax, but unaltered KD, values were observed immediately after the stress as compared to the controls. Ten days after the stress, a slight decrease (15%) in the number of peripheral benzodiazepine binding sites was observed, but their values remained higher (29%) in comparison to unstressed controls. Levels of plasma stress hormones (cortisol, growth hormone, and prolactin) did not differ in the stressed subjects from those of the controls.