Increased sensitivity of platelets to adrenaline in human myotonic dystrophy

Platelets from patients with myotonic dystrophy showed a normal pattern of aggregation in response to adenosine diphosphate (A.D.P.) and collagen but were unusually sensitive to adrenaline, aggregation being detectable with adrenaline concentrations as low as 0.041 mumol per litre. In other diseases in which such sensitivity has been reported this has been accompanied by a similarly altered response to A.D.P. The increased platelet aggregation could be due to increased uptake of Ca++ by platelets or to a decrease in phosphorylation of the platelet membrane.