Temperature effects on the activity, shape, and storage of platelets from 13-lined ground squirrels.
The objective of this study is to determine how a hibernating mammal avoids the formation of blood clots under periods of low blood flow. A microfluidic vascular injury model was performed to differentiate the effects of temperature and shear rate on platelet adhesion to collagen. Human and ground squirrel whole blood was incubated at 15 or 37 °C and then passed through a microfluidic chamber over a 250-µm strip of type I fibrillar collagen at that temperature and the shear rates of 50 or 300 s-1to simulate torpid and aroused conditions, respectively. At 15 °C, both human and ground squirrel platelets showed a 90-95% decrease in accumulation on collagen independent of shear rate. At 37 °C, human platelet accumulation reduced by 50% at 50 s-1compared to 300 s-1, while ground squirrel platelet accumulation dropped by 80%. When compared to platelets from non-hibernating animals, platelets from animals collected after arousal from torpor showed a 60% decrease in binding at 37 °C and 300 s-1, but a 2.5-fold increase in binding at 15 °C and 50 s-1. vWF binding in platelets from hibernating ground squirrels was decreased by 50% relative to non-hibernating platelets. The source of the plasma that platelets were stored in did not affect the results indicating that the decreased vWF binding was a property of the platelets. Upon chilling, ground squirrel platelets increase microtubule assembly leading to the formation of long rods. This shape change is concurrent with sequestration of platelets in the liver and not the spleen. In conclusion, it appears that ground squirrel platelets are sequestered in the liver during torpor and have reduced binding capacity for plasma vWF and lower accumulation on collagen at low shear rates and after storage at cold temperatures, while still being activated by external agonists. These adaptations would protect the animals from spontaneous thrombus formation during torpor but allow them to restore normal platelet function upon arousal.
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA. scooper@uwlax.edu.
Scott
http://orcid.org/0000-0002-2555-6457
S
Cooper
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Sarah
S
Lloyd
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Anthony
A
Koch
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Xingxing
X
Lin
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Katie
K
Dobbs
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Thomas
T
Theisen
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Matt
M
Zuberbuehler
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Kaley
K
Bernhardt
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Michael
M
Gyorfi
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Tanner
T
Tenpas
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Skyler
S
Hying
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Sarah
S
Mortimer
Biology Department, University of Wisconsin-La Crosse, 1725 State St., La Crosse, WI, 54601, USA.
Christine
C
Lamont
Chemical and Biological Engineering Department, Colorado School of Mines, Golden, CO, 80401, USA.
Marcus
M
Lehmann
Chemical and Biological Engineering Department, Colorado School of Mines, Golden, CO, 80401, USA.
Keith
K
Neeves
D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D003094:Collagen / Q000502:physiology; D005340:Fibrinogen / Q000502:physiology; D006801:Humans; D012589:Sciuridae / Q000502:physiology*; D013696:Temperature; D064348:Torpor / Q000502:physiology*; D014841:von Willebrand Factor / Q000502:physiology
D014841:von Willebrand Factor; D005340:Fibrinogen; D003094:Collagen
Collagen; Fibrinogen; Hypothermia; Tubulin; Von Willebrand factor