Does hypertension confer a hypercoagulable state in stroke-prone spontaneously hypertensive rats?

Area of Science:

• Coagulation science
• Hypertension research
• Animal models of disease

Background:

• Hypertension is often associated with a hypercoagulable state, increasing thrombotic risk.
• Stroke-prone spontaneously hypertensive rats (SHR-SP) are a valuable model for studying hypertension-related complications.
• The specific impact of hypertension on coagulation parameters in SHR-SP requires detailed investigation.

Purpose of the Study:

• To determine if hypertension induces a hypercoagulable state in the SHR-SP rat model.
• To compare blood coagulation parameters between SHR-SP and normotensive Wistar-Kyoto (WKY) rats.

Main Methods:

• Coagulation assays including prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, and specific factors were performed.
• Measurements were conducted in young (8-12 weeks) and older (16-20 weeks) SHR-SP and WKY rats.
• Levels of fibrin/fibrinogen degradation products (FDP), thrombin-antithrombin III complex (TAT), factor Xa, antithrombin III (AT-III), tissue factor pathway inhibitor (TFPI), protein C, and C1 inhibitor were assessed.

Main Results:

• No significant differences in FDP or TAT levels were observed between SHR-SP and WKY rats, even in older animals with severe vascular lesions.
• Contrary to expectations, SHR-SP rats exhibited significantly lower fluorogenic PT and factor Xa activity compared to WKY rats.
• Elevated C1 inhibitor activity in SHR-SP rats was inversely correlated with reduced factor Xa activity, suggesting an inhibitory role.

Conclusions:

• The study suggests that SHR-SP rats develop a hypocoagulable state rather than a hypercoagulable one.
• Reduced factor Xa activity in SHR-SP rats appears to be linked to increased C1 inhibitor activity.
• These findings challenge the assumption of a hypercoagulable state in this hypertensive model and highlight the role of C1 inhibitor.