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Sustained hypothermia accelerates microvascular thrombus formation in mice.
Nicole Lindenblatt1, Michael D Menger, Ernst Klar
1Dept. of Experimental Surgery and Dept. of General Surgery, Univ. of Rostock, Schillingallee 70, 18055 Rostock, Germany. niclindenblatt@hotmail.com
American Journal of Physiology. Heart and Circulatory Physiology
|August 16, 2005
Summary
Mild hypothermia accelerates microvascular thrombosis by increasing platelet activation. However, this effect is temporary, with no increased thrombosis risk after rewarming to normal body temperature.
Area of Science:
- Physiology
- Hematology
- Vascular Biology
Background:
- Systemic hypothermia is associated with altered blood coagulation and increased thrombosis risk.
- Understanding the impact of hypothermia on microvascular thrombosis is crucial for clinical management.
Purpose of the Study:
- To investigate the effect of systemic hypothermia on microvascular thrombus formation in vivo and in vitro.
- To determine if hypothermia enhances platelet activation and predisposes to thrombosis.
Main Methods:
- Ferric chloride-induced microvascular thrombus formation in hypothermic mouse cremaster muscle preparations.
- Flow cytometry and Western blot analysis to assess platelet activation (PAC-1 binding, fibrinogen binding, tyrosine phosphorylation).
- Experiments conducted at normothermia (37°C), moderate hypothermia (34°C), and severe hypothermia (31°C), with subsequent rewarming.
Main Results:
- Systemic hypothermia significantly accelerated microvascular thrombus formation in arterioles and venules.
- Platelet activation, measured by glycoprotein (GP)IIb-IIIa and fibrinogen binding, increased with decreasing temperatures.
- Tyrosine-specific protein phosphorylation in platelets was elevated during hypothermia.
- Rewarmed animals showed thrombus formation kinetics comparable to normothermic controls, with no enhanced GPIIb-IIIa activation.
Conclusions:
- Moderate systemic hypothermia accelerates microvascular thrombosis, potentially through enhanced platelet GPIIb-IIIa activation.
- Hypothermia does not lead to a predisposition for increased microvascular thrombus formation after rewarming to normothermia.