Platelet microtubule shape changes at 4°C. Panel A: Ground squirrel platelet rich plasma was incubated at 37°C for 2 hours and then place on ice. At each time point, aliquots were removed, centrifuged onto polylysine coated microscope slides, fixed and the percentage of platelets in a rod shape counted. The cold storage curve fit best to a hyperbolic curve, F= 0.312*x/(14.67+x). N=6 samples run in duplicate and time points at 30, 60, 90 and 120 minutes compared by student t-test. Panel B: Taxol treated platelets showed increased rod formation even at 37°C, while no changes were observed in control or nocodazole treated platelets. Panel C: Taxol treated platelets form rods and will not revert to rings upon rewarming to 37°C unlike control or nocodazole treated platelets. N=6 samples run in duplicate and analyzed by student t-test, bars with different letters were significantly different, p<0.05.