Dose-Response Aggregometry in Maternal/Neonatal Platelets

Abstract

SummaryThe aggregation of platelets collected from maternal/neonatal pairs (n = 240) at the time of childbirth, was studied in response to multiple doses of ADP, collagen, arachidonic acid and ristocetin. Similar responses were obtained from healthy nonpregnant adult controls for comparison. The lag phase, slope of the aggregation curves as well as maximum aggregation (MA%) were recorded and analysed. Neonatal and adult platelets exhibited more enhanced responses to decreasing doses of ADP, arachidonic acid and ristocetin, than maternal platelets. These enhanced responses were exhibited more consistantly in the slopes of the aggregation curves than in MA%. Although neonatal platelets have shown longer lag phase in their responses to collagen, the rate of the aggregation reaction was significantly faster than maternal platelets, with no differences in MA%. These results contradict many previous reports suggesting impaired aggregation responses of neonatal platelets to these agonist. The possible reasons for these contradictions were discussed.

Hemostasis in Pregnant Saudi Women

“…[3][4][5] Samples for coagulation assays were transported in ice to the laboratory, where plasma was separated at 4°C and stored at -40°C for analysis at a later date. Platelet-rich plasma (PRP) used for platelet aggregation studies was prepared by centrifuging citrate blood samples at 150 g for seven minutes at room temperature (23°C).…”

“…5 All concentrations of the aggregating agents were final concentrations obtained by adding 20 μl of agonist to 180 μl of PRP in an aggregometer (Aggregation Profiler PAP4; Bio/Data Corp, U.S.A.). The results obtained in the pregnant women were compared to reference values for healthy Saudi women, aged 12 to 50 years (to be published).…”

Hereditary Bleeding Disorders in Riyadh, Saudi Arabia

“…Platelet aggregation was undertaken in platelet-rich plasma using the following agonists (ADP, adrenaline, collagen, arachidonic acid, and ristocetin), observing the usual precautions and as detailed elsewhere. 13 Tests were performed only if the patient had not been on any form of drug therapy for at least two weeks before giving blood, and whenever possible, repetition of the test was undertaken.…”

Hemostatic Changes Following Surgery

“…Platelet aggregation was performed in response to ADP (20, 2.0, 1.0 and 0.5 μΜ/L), collagen 0.19 g/L, arachidonic acid (1.64 mmol/L) and ristocetin (150, 120 and 100 mg/dl) as detailed recently [17]. All these concentrations of the aggregating agents were final concentrations obtained by adding 20 μl of agonist to 180 μl platelet rich plasma in an aggregometer (Aggregation Profiler -PAP4 -Bio/Data Corp., USA).…”