Increased Thrombin Sensitivity of Human Platelets After Storage at 4 C

Abstract

In vitro function of fresh platelets and platelets stored for 24 hours at 4 C and 22 C was studied using the release of 14C‐5‐hydroxytryptamine (5‐HT), adenine nucleotides and calcium following stimulation with thrombin. Storage of platelets did not affect 14C‐5‐HT uptake capability, adenine nucleotide content or adenine nucleotide release. Platelets stored in 4 C varied from fresh platelets and 22 C‐stored platelets with respect to 5‐HT and calcium release. For measurement of 5‐HT release, different thrombin‐to‐platelet concentrations were used. At thrombin‐to‐platelet concentrations of 0.013 to 0.02 U/108 platelets, 4 C‐stored platelets released more 5‐HT than did fresh platelets. Differences between 4 C‐stored platelets and 22 C stored platelets were observed over a wider range of thrombin‐to‐plate‐lets concentrations. The 4 C‐stored platelets released significantly greater amounts of 5‐HT at thrombin‐to‐platelet concentrations of 0.008‐0.02 L/ml. Calcium release, measured with the calcium electrode, was studied at high (1.0 L/ml) and low (0.06 U/ml) thrombin concentrations and at a platelet concentration of 8 × 108 platelets/ml. At the high thrombin concentration, the amount of calcium released was the same for all platelets studied. At the low thrombin concentration, platelets stored at 4 C released a greater amount of calcium than did either fresh platelets or platelets stored at 22 C. The results obtained with different thrombin‐to‐platelet concentrations suggest that there is only a narrow range of thrombin concentrations per platelet at which the subtle differences between platelet populations may be detected. The range may reflect the threshold concentration of thrombin that is required to initiate a release reaction. The apparently lower thrombin threshold required by 4 C platelets to undergo a release reaction may be a factor contributing to their reduced circulation and superior hemostatic effectiveness.

In vitro Measurements of Platelet Concentrates Stored at 4 and 22°C: Correlation with Posttransfusion Platelet Viability and Function

“…After 4°C storage, this measurement consistently overesti mated posttransfusion viability [16,20,23]. Measurements of serotonin uptake seem to be both unreliable and insensitive [24,26,27]. pH adjustment.…”

“…Whether platelets were stored for 3 days at 4 or 22 °C there was a partial degradation (20-40%) of the myo sin [39], Other investigators [27] found a sig nificant decrease in the amount of actinbinding protein during room-temperature platelet concentrate storage. rangements occur in platelets stored at 22 thari at 4 °C.…”

“…The amount of serotonin released by platelets treated with thrombin was progressively reduced with storage time. Studies by Robblee et al [27] used conditions different from the usual platelet concentrate storage, in that 25-ml samples were stored in 150-ml bags. They found no differences between the serotonin uptake of platelets stored at 4 and 22 °C for 24 h. However, the thrombin-induced re lease of either serotonin or calcium after 22 °C storage was the same as that of fresh platelets, but significantly decreased after 4°C storage.…”

“…in the study of Murphy and Gardner [3] Similarly, investigations of total ATP and because there was better gas transport across ADP levels in 4 and 22°C-stored platelet the plastic of the bags they used. Beutler and concentrates rather than PRP have shown Kuhl [29] also found increased lactate con-levels at least 65% ofbaseline [15,22,25,27], centration during 22 °C storage, but this was In a more recent study [32], the metaboliattributed to white-cell contamination. In cally active, as well as total ATP and ADP their study, the correlation coefficients be-levels were measured during 72 h of platelet tween white-cell and hydrogen-ion concen-concentrate storage at 22 °C, and no appretration and lactate production were 0.69 and ciable changes were found.…”

Platelet Storage Temperature – How Low Can We Go?

“…However, other investigators have reported the opposite, that refrigeration (< 21 days) retards the release of α-granule contents such as β-thromboglobulin [12,39,40]. Refrigerated platelets spontaneously form aggregates [41,42], respond better to agonists than room temperature platelets [11,[43][44][45][46][47][48][49][50][51], and adhere better to von Willebrand factor (vWf) under shear stress [52,53]. Furthermore, a recent study shows that systemic hypothermia of 31-34 °C in mice accelerates thrombus formation in arterioles and venules [43], indicating that exposure to temperatures below the physiological norm may activate platelets in vivo.…”