Desmopressin-induced improvement in bleeding times in chronic renal failure patients correlates with platelet serotonin uptake and ATP release.

Hemostatic defects resulting in life-threatening hemorrhagic episodes are a common occurrence in the chronic renal failure patient. Hemorrhagic tendencies correlate best with laboratory tests of bleeding times. The identification of a specific hemostatic defect and its role in bleeding dyscrasias has yet to be elucidated. Our studies demonstrate that factor VIII coagulant activity and factor VIII related antigen (vWF:Ag) are normal or greatly elevated in uremic renal failure patients with greatly prolonged bleeding times. The multimeric state of the von Willebrand factor is also normal in these patients. The bleeding times were normalized in all 15 patients, 90 minutes post-infusion with desmopressin (DDAVP). No significant changes in factor VIII/vWF associated properties, blood cell counts, or coagulation factors were observed post-DDAVP treatment. However, a significant increase in platelet serotonin uptake (p less than .025) and ATP release (p less than .025) was detected after DDAVP treatment. These results indicate that DDAVP acts on the platelet membrane. This is further substantiated by the ability of DDAVP to block vasopressin-induced platelet aggregation in a dose- and time-dependent fashion. Perturbations in the movement and storage of serotonin and the release of adenosine 5'-triphosphate (ATP) in the platelets of uremic individuals are proposed to play a critical role in regulating bleeding times.

Selective reduction of serotonin storage and ATP release in chronic renal failure patients platelets.

Hemorrhagic complications, as monitored by skin bleeding times, occur in a significant number of chronic renal failure (CRF) patients. The etiology of hemostatic defects in these patients is complex and ill defined. Our studies demonstrate, for the first time, that activated platelets, derived from CRF patients, release significantly (P less than .001) less ATP than controls while the percent of releasable serotonin (5HT), assumed to be co-stored with ATP, is unaltered. Analysis of the CRF-derived platelets reflects a selective acquired storage pool defect with significantly (P less than .001) reduced 5HT levels while their dense granule contents of ATP and ADP are normal. The comparison of ATP release from platelets derived from CRF patients whose bleeding times were less than 9 min to those with bleeding times of 9 min or greater was significantly different (P less than .02). This report demonstrates for the first time that there is a statistically significant correlation of ATP release and 5HT content to bleeding times (P less than .001). The perturbation of platelet 5HT uptake, 5HT dense granule content, and ATP release appears to result from newly described altered plasma factors, detected by our in vitro mixing studies. It is proposed that the reduced level of releasable platelet 5HT and ATP contributes to bleeding disorders commonly encountered in CRF patients.