Effects of exercise on platelet and aortic functions in aged rats.
OBJECTIVE
To assess age- and exercise-related changes in platelet aggregation, we measured the magnitude of platelet aggregation with a four-channel aggregometer, plasma and aortic polyunsaturated fatty acids by gas chromatography and related prostanoids with a reagent kit in young and aged non-exercised and in aged exercised rats.


RESULTS
Platelet aggregation in platelet-rich plasma induced by ADP (5 microm) in the primary wave increased with age. In the non-exercised groups, the basal levels of thromboxane B2 in platelet-rich plasma increased in aged rats compared with young rats. In aged exercised rats, the basal levels of 6-keto-prostaglandin F1alpha in platelet-rich plasma were stimulated and those of thromboxane B2 were depressed, compared with non-exercised aged rats. The plasma levels of eicosapentaenoic acid and docosahexaenoic acid increased with age. Only aortic eicosapentaenoic acid in the aged group increased by exercise. In the aged non-exercised and exercised groups, the aortic, but not the plasma, levels of eicosapentaenoic acid correlated inversely with the basal levels of thromboxane B2 in platelet-rich plasma (r = -0.53, P < 0.05) and associated negatively with the magnitudes of platelet aggregation induced by ADP (5 microm) (r = -0.47, P < 0.05).


CONCLUSIONS
These findings suggest that exercise in aged rats increases aortic eicosapentaenoic acid concentrations, which in turn depress the basal levels of thromboxane, B2 in platelet-rich plasma to modulate platelet aggregation.
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000244:Adenosine Diphosphate / Q000378:metabolism; D000375:Aging / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000502:physiology*; D002849:Chromatography, Gas / Q000379:methods; D004281:Docosahexaenoic Acids / Q000097:blood; D015118:Eicosapentaenoic Acid / Q000097:blood; D002149:Energy Intake; D005231:Fatty Acids, Unsaturated / Q000097:blood; D005260:Female; D007124:Immunoenzyme Techniques / Q000379:methods; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010974:Platelet Aggregation / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013929:Thromboxane B2 / Q000097:blood; D015430:Weight Gain
D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D000244:Adenosine Diphosphate; D015118:Eicosapentaenoic Acid