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.
