Platelets from patients on haemodialysis show impaired responses to nitric oxide

1. Platelets from patients on haemodialysis showed a loss of sensitivity to nitric oxide, reflected by a reduction in the ability of nitric oxide both to inhibit thrombin-induced aggregation and to increase intraplatelet cyclic GMP levels. Responses of platelets from patients on continuous ambulatory peritoneal dialysis were slightly, but not significantly, impaired. Platelets from both groups of uraemic patients showed normal sensitivity to the cyclic AMP-dependent inhibitor prostacyclin. 2. Reduced levels of cyclic GMP in response to nitric oxide in platelets from patients on haemodialysis were due to a defect in its generation, rather than to accelerated breakdown. 3. Basal levels of intra-platelet cyclic GMP were significantly increased in both patients on haemodialysis and patients on continuous ambulatory peritoneal dialysis. 4. The activity of nitric oxide was more stable in plasma than in buffer; its survival in plasma from patients on haemodialysis was similar to that in plasma from healthy control subjects.