Vesiculation and changes in fluidity and lipid composition of platelet membranes after storage of sheep platelets in plasma or Seto solution.
To relate the improvement of platelet storage in synthetic media with possible structural changes, we conducted serial studies on the membranes of platelets and microparticles shed during platelet storage for up to 5 days at 4 degrees C either in plasma or in Seto solution. Spontaneous microparticle formation proceeded linearly for up to 2 days in both storage media, although the processes seemed to be different because microparticles from Seto solution had a higher lipid/protein ratio than those released in plasma. Microparticles were heterogeneous structures showing beta-N-acetylhexosaminidase, glucose-6-phosphatase and succinate dehydrogenase activities. After 2-5 days of storage, microparticles contained 60% of total cellular acetylcholinesterase (AChE), were doubly enriched in cholesterol. and showed identical phospholipid profiles but with a decrease in the lipid unsaturation index with respect to fresh platelets. Fluorescence anisotropy studies pointed to a remarkable increase in the deep lipid core fluidity of microparticles during storage of platelets in plasma. With respect to platelets, only those stored in plasma showed significant changes in lipid contents, with a 3-fold decrease in the phospholipid to protein ratio, a decrease in phosphatidylethanolamine (PE) levels and a parallel increase in phosphatidylcholine (PC) percentages in their phospholipid profile, together with a significant reduction in the lipid unsaturation index after 1 day of storage. The fluidity of the negatively charged surface of the platelet membranes decreased in platelets stored for 5 days in both media, whereas the fluidity of the membrane deep core was only increased in platelets stored in plasma. These findings suggest that Seto solution permits better storage of platelets for 5 days than plasma and support the notion that lipid peroxidation could play an important role in the structural changes observed.
Martín-Valmaseda
E M
EM
Department of Biochemistry and Molecular Biology, University of Salamanca, Spain.
Sánchez-Yagüe
J
J
Hernández-Hernández
A
A
Llanillo
M
M
D000818:Animals; D001792:Blood Platelets; D001793:Blood Preservation; D002462:Cell Membrane; D005950:Glucose Solution, Hypertonic; D008055:Lipids; D008560:Membrane Fluidity; D019188:Organ Preservation Solutions; D010949:Plasma; D012756:Sheep
D005950:Glucose Solution, Hypertonic; D008055:Lipids; D019188:Organ Preservation Solutions; C076429:Seto solution