Platelet activation and platelet-derived growth factor (PDGF) play a pivotal role in the pathogenesis of atherosclerosis. Evidence has been accumulating that in the evolution of chronic arterial obstructive disease (CAOD) platelets are also crucially important. The aim of the present study was, therefore, to assess plasma levels of PDGF in patients with different degrees of CAOD according to Fontaine.

Twenty patients (17 men, 3 women, mean age sixty-eight ± seven years) with inter mittent claudication (Fontaine stage II) entered the study and their PDGF levels were assessed by radioimmunoassay. Ten additional patients (7 men, 3 women, mean age seventy-three ± seven years) with more severe CAOD (leg pain at rest/skin ulcers) were also studied. Ten healthy subjects (6 men, 4 women, mean age fifty-four ±six years) comprised the control group. Patients in stage II were reinvestigated after sixty days of a "training" procedure.

Patients with both intermittent claudication and more severe disease had higher levels of PDGF than controls (controls 165.9 ±119.1 pg/mL; Fontaine stage II 403.5 ±218.4; Fontaine stage III/IV 578.1 ±637.2: ANOVA P = 0.04) with no difference between the two groups of patients. After the training period, PDGF levels were signifi cantly higher than at baseline (863.7 ±819.6 pg/mL vs 403.5 ±218.4) but without signif icant improvement of physical performance. (continued on next page)

The elevation of PDGF levels in blood from CAOD patients could be the result of marked platelet activation due to interaction with a widely damaged peripheral vascula ture. The same was not true for coronary heart disease, in which normal values of PDGF in venous blood were found. Nevertheless, as in acute coronary syndromes, PDGF increases when the clinical picture improves, perhaps in relation to its reduced consump tion in vessel walls.