Effects of pentoxifylline on Ca2+-dependent transglutaminase in rat erythrocytes.
We have examined the effects of pentoxifylline, a drug used to improve peripheral blood flow in patients with chronic vascular disorders, on shear-induced Ca2+ entry and Ca2+-dependent protein crosslinking in the erythrocyte. Cells were washed in isosmotic bicarbonate buffer, pH 7.5, and brought to a 20% suspension. 5 ml samples were sheared by swirling them for seconds; 45Ca2+ uptake, activation of Ca2+-dependent transglutaminase, and products of the crosslinking reaction were measured. A 5 second shear promoted 45Ca2+ entry, activation of Ca2+-dependent transglutaminase and crosslinking of proteins in the membrane-cytoskeletal fraction. Pentoxifylline, a drug that promotes erythrocyte deformability, diminished Ca2+ entry and inhibited activation of Ca2+-dependent transglutaminase, and had a prophylactic role on the effects of Ca2+ entry due to shear. Incubation of cells with 2.5 mM pentoxifylline before swirling minimized the effects of shear on 45Ca2+ entry, Ca2+-dependent transglutaminase and crosslinking of proteins. This study indicates that pentoxifylline promotes erythrocyte flexibility by minimizing shear-induced Ca2+ entry and Ca2+-dependent crosslinking.
Swislocki
N I
NI
Department of Biochemistry and Molecular Biology, UMD-New Jersey Medical School, Newark 07103-2757.
Tierney
J M
JM
D000818:Animals; D002118:Calcium / Q000097:blood*; D002132:Calcium Radioisotopes; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology*; D006461:Hemolysis / Q000187:drug effects; D007811:Lanthanum / Q000097:blood; D008297:Male; D010431:Pentoxifylline / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013805:Theobromine / Q000031:analogs & derivatives*; D011503:Transglutaminases / Q000032:analysis*
D002132:Calcium Radioisotopes; D007811:Lanthanum; D011503:Transglutaminases; D013805:Theobromine; D010431:Pentoxifylline; D002118:Calcium