Increased platelet aggregation and release reaction in myotonic dystrophy

Platelet aggregation (PA) induced by (-)-epinephrine and adenosine diphosphate (ADP) was studied in 16 patients with myotonic dystrophy (MyD) and 14 healthy subjects. Plasma beta-thromboglobulin level (beta-TG), a useful marker of in vivo platelet release reaction, as well as in vitro 5-[14C]hydroxytryptamine (5-HT) release, were also studied. The extent of PA induced by (-)-epinephrine at 1 and 3 min and by ADP at 3 min was significantly higher in the patients than in controls. Plasma beta-TG and ADP- or epinephrine-induced platelet 5-HT release were also increased in MyD patients. These results suggest that an abnormality in release as well as in alpha 2-receptor functioning occurs in the platelets of MyD patients. The relation of this abnormality to changes in Ca2+ fluxes through the platelet membrane is discussed.