Investigations on Adenosine Diphosphate (ADP) Induced Platelet Adhesiveness in Vitro

Abstract

SummaryThe ADP-induced platelet adhesiveness has been investigated under experimental various conditions by the in vitro method of Hellem. The platelet, adhesiveness was found to be proportional to the logarithm of the ADP concentrations between 0.025—0.2 μg/ml in citrated and heparinized plasma. The effect of ADP on platelets decreased with increasing concentrations of citrate. In contrast, increasing amounts of heparin did not alter the platelet adhesiveness significantly, except when extremely high concentrations were used. Variations in the temperature highly influenced the result of the estimations when suboptimal concentrations of ADP were used. The reason for this probably inactivation of ADP by plasma enzymes, which have an optimal activity at about 37° C. This may explain why estimation at 20° C gives higher values of the platelet adhesiveness than at 37° C. If too high concentrations of ADP are used, this effect is not detectable. This may be the reason why O’Brien (1962) did not find any inactivating property of platelet poor plasma. Washing of platelets in buffered saline leads to a marked release of ADP, indicating that washed platelets are damaged. Repeated resuspension of platelets even in their own plasma gives release of ADP. When studying the mechanism of the ADP-induced reaction all the above variations must be taken into account.

Dietary Fats and Arterial Thrombosis

“…After 18 and 62 weeks' feeding, platelet adhesiveness determined by the modified glass bead test [50] was not significantly different. In an earlier investigation [124] rabbits were fed a 1:1 mixture of maize and coconut oil (15 % fat in the diet), while another group was fed these dietary fats separately during alternate periods of 10 weeks.…”

“…N ordoy [99], using the modified glass bead test [50], measured ADP-induced platelet adhesiveness in citrated platelet-rich plasma of rats fed a normal stock diet (control group) or a saturated fat diet containing 10% hydrogenated co conut oil and 1 % cholesterol for 4 months. During the last month, animals on the saturated fat diet were daily administered 80 mg maize oil, linseed oil or water.…”

“…M u stard and M urphy [88] did not find significant effects on the platelet ad hesive index (glass wool braid) of diets containing either 21 cal% mixed vegetable fats, 37 cal % vegetable fats (mainly maize oil) or 39 cal % mixed animal fats, fed for 4 weeks to normal volunteers. Owren et al [105] showed that maize oil, cod liver oil and safflower oil in doses of 100 ml/day were rather ineffective in changing the increased platelet adhesiveness in ather osclerotic patients (modified glass bead test [50]) while soybean oil nor malized it within 3 days. Linseed oil was reported to be extremely beneficial in this respect, but this was revoked later [106].…”

“…Evans and Irvine [32] showed that increased platelet adhesive ness is associated with a reduction of the long-term patency of Dacron® femoropopliteal bypass grafts in men. They found that linseed and maize oil, 2 x5 ml daily for 1 month, failed to reduce platelet adhesiveness in vitro (modified glass bead column technique [50]. Because of the increasing availa bility of shunt-bearing patients, a clinical trial on the use of antithrombotic dietary fats to increase graft patency should be considered.…”

Thrombosis and hemorheology

“…), platelet retention in glass bead columns measures both platelet adhesion and platelet aggregation (or cohesion) [19]. Hellem [37] showed that platelet retention in whole blood depended on the hematocrit, and that if platelet-rich plasma was used, few platelets were retained unless ADP was added [38]. Harrison and Mitchell [39] abolished the difference in platelet retention between blood and platelet-rich plasma by adding the pyruvate kinase system, which removes ADP.…”