Alteration in Second Phase Platelet Aggregation Associated with an Emotionally Stressful Activity

Summary

23 healthy house staff officers were studied for platelet aggregation changes immediately prior to, immediately after and at a 7 to 11 day interval after their presenting a case before the Medical Mortality Conference. In 12 of the 23 with epinephrine (2.5 × 10⁻⁶M) and 11 of the 23 with ADP (2.0 × 10⁻⁶M) an absence of second phase aggregation was noted. A total of 19 of the 23 with epinephrine (2.5 × 10⁻⁶M) either had absent second phase or had a decreased slope of second phase aggregation. In all subjects except two a return to normal pattern was noted in the recovery samples 7 to 11 days later.

In 5 subjects who had absent second phase aggregation with epinephrine (2.5 × 10-6M) immediately after presentation, one had a return toward normal at 24 hours while the others were resistant to higher concentrations of epinephrine (2.5 × 10⁻⁵M and 2.5 × 10⁻⁴M). One subject in the immediate post presentation period had a slight improvement in second phase aggregation with 2.5 × 10⁻⁴M epinephrine.

Platelet counts increased in 5 of 6 subjects in the immediate post presentation period and did not necessarily correlate with the absence of second phase aggregation.

ADP/ATP platelet content increased in the post presentation samples.

We can conclude that during and immediately after an activity associated with stress, platelet changes can occur characterized by a decreased second phase aggregation with epinephrine or ADP. These changes last for at least 24 hours and are resistant to higher concentrations of epinephrine.

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