Cord blood platelet aggregation; quality control by a two-sample technique

Arachidonic-acid-induced platelet aggregation is increased in male but not in female smokers

Arachidonic-acid-induced platelet aggregation was studied in 40 healthy drug-free subjects aged 18-43 years. Aggregation was elicited by lower concentrations of arachidonic acid in smoking men (n = 10) than in non-smoking men (n = 10)(p less than 0.05). No significant difference was found between smoking and nonsmoking females. Adenosine-diphosphate-induced platelet aggregation was not increased in smokers. There was no difference between smokers and non-smokers with respect to mean platelet volume and count within each sex. Females and males differed regarding platelet count in whole blood and platelet sensitivity to arachidonic acid; both differences were secondary to the difference in hematocrit. The parallelism between an increased tendency to aggregation after arachidonic acid stimulation and an increased rate of myocardial infarction in male smokers, and the absence of both these phenomena in female smokers, might be of pathophysiological significance.

Aggregation of and thromboxane B2 synthesis in platelets from newborn infants of smoking and non-smoking mothers

Cord blood platelet aggregation and thromboxane B2 (TxB2) synthesis were investigated in 20 healthy infants of drug-free healthy mothers with an uncomplicated pregnancy ending at term in a normal vaginal delivery. Eight of the mothers were habitual smokers and the remaining 12 were non-smokers. The platelet count was slightly lower in infants of smoking mothers than in the control infants. There were no differences between the two groups in the qualitative or quantitative aggregation responses (maximal change in optical density) to stimulation by 0.55, 1.1, 3.3 and 6.6 microM adenosine diphosphate, 0.5 and 1.0 mM arachidonic acid (AA) or collagen 1.0 and 5.5 mg/l. Nor was there any difference between the groups in regard to TxB2 synthesis after stimulation by these substances. The amount of TxB2 synthesized merely reflected the occurrence of reversible or irreversible platelet aggregation. Stimulation of platelets by AA induced by far the highest synthesis of TxB2. The generally decreased aggregability of platelets of newborn infants, compared with that in adults, was confirmed in this study. No effect of maternal smoking during pregnancy on the prostaglandin-dependent pathway of aggregation of cord blood platelets was demonstrated.