Digital blood flow and 5‐hydroxytryptamine receptor blockade after ketanserin in patients with Raynaud's phenomenon.

Abstract

1. The effect of ketanserin on digital blood flow and 5‐ hydroxytryptamine (5‐HT)‐induced platelet aggregation was studied in 18 patients with Raynaud's phenomenon. 2. Measurements were made before and after a single dose of 20 mg ketanserin and again after 1 month of continuous treatment with 20 mg ketanserin three times a day. 3. Digital blood flow was assessed by changes in digital pulse volume; platelet aggregation by changes in light transmission after challenge with 10(‐5) M 5‐HT. 4. Ketanserin induced a rise in digital blood flow and blocked the platelet response to 5‐HT; the two events were not correlated and were independent of subjective improvement. 5. These data do not support the suggestion that 5‐HT2‐receptor blockade is of major importance in the dilatory effect of ketanserin in Raynaud's phenomenon. 1990 The British Pharmacological Society