Relationship between changes in platelet reactivity and changes in platelet receptor expression induced by physical exercise.
BACKGROUND
In previous studies we have consistently shown a significant increase of platelet reactivity after exercise in patients with obstructive coronary artery disease (CAD). We also observed a significant individual variability in the response to exercise of platelet reactivity in these patients. Whether exercise-induced changes in platelet reactivity correlate with changes in platelet membrane receptors in patients with CAD is unknown.


METHODS
We studied 26 patients with stable CAD and 10 matched healthy controls who underwent a symptom-limited treadmill exercise stress test. Venous blood samples were collected at rest and within 5 min of peak exercise. Platelet reactivity was measured by the PFA-100 method as time to occlude (closure time, CT) a ring coated with collagen/adenosine diphosphate (C/ADP). Platelet expression of glycoprotein (GP) IIb/IIIa, in both global (CD41) and active form (PAC-1), and P-selectin (CD62P) and formation of leukocyte-platelet aggregates were assessed by flow cytometry.


RESULTS
After exercise CT did not change in controls (85.4+/-12 to 84.0+/-9 s, p=0.37), whereas it decreased in CAD patients (98.8+/-24 to 91.4+/-25 s, p<0.001). After exercise, CD41 and PAC-1 platelet expression increased significantly in CAD patients (p=0.04 for both), but not in controls (p=0.39 and p=0.98, respectively). To evaluate the relationship between the response to exercise of platelet reactivity and of platelet receptor expression, CAD patients were divided into two groups: CAD group 1 (16 patients, decrease in CT >5 s after exercise) and CAD group 2 (10 patients no increase in platelet reactivity after exercise). CD41 and PAC-1 expression increased in CAD group 1 (p=0.008 and p=0.026, respectively) but not in CAD group 2 (p=0.39 and p=0.50, respectively). No significant differences were observed between the 2 groups for changes in CD62P and leukocyte-platelet aggregates.


CONCLUSIONS
Our data show that, in patients with stable CAD, an increased platelet reactivity to C/ADP stimulation after exercise, as assessed by the PFA-100 method, is specifically associated with an increased expression of platelet GP IIb/IIIa receptor.
Aurigemma
Cristina
C
Institute of Cardiology, Università Cattolica del Sacro Cuore, Rome, Italy.
Fattorossi
Andrea
A
Sestito
Alfonso
A
Sgueglia
Gregory A
GA
Farnetti
Sara
S
Buzzonetti
Alexia
A
Infusino
Fabio
F
Landolfi
Raffaele
R
Scambia
Giovanni
G
Crea
Filippo
F
Lanza
Gaetano A
GA
D000368:Aged; D001792:Blood Platelets / Q000502:physiology*; D003324:Coronary Artery Disease / Q000097:blood* / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D039661:Integrin beta3 / Q000378:metabolism; D007962:Leukocytes / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D019007:P-Selectin / Q000378:metabolism; D015539:Platelet Activation / Q000502:physiology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism
D039661:Integrin beta3; D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D040201:Platelet Membrane Glycoprotein IIb