Anticoagulantly active heparin-like molecules from vascular tissue

Area of Science:

• Biochemistry
• Vascular Biology
• Pharmacology

Background:

• Mucopolysaccharides are complex carbohydrates with diverse biological roles.
• Heparin and related compounds are known for their anticoagulant properties.
• Understanding the distribution and activity of these compounds in different vascular tissues is important.

Purpose of the Study:

• To isolate and characterize heparin-like mucopolysaccharides from calf cerebral microvasculature and aorta.
• To compare the anticoagulant activities of these isolated compounds.
• To investigate the localization of anticoagulantly active components within the aorta.

Main Methods:

• Isolation of mucopolysaccharides from calf cerebral microvasculature and aorta.
• Assay of anticoagulant activity using anti-factor Xa and anti-factor IIa units.
• Affinity fractionation using antithrombin.
• Characterization of molecular weight and charge density.

Main Results:

• Heparin-like components were the only complex carbohydrates exhibiting anticoagulant activity.
• Calf cerebral microvascular heparin-like species showed higher anti-factor Xa (2.92 U/mg) and anti-factor IIa (2.85 U/mg) activity compared to aortic species (0.56 U/mg and 0.19 U/mg, respectively).
• Highly purified cerebral microvascular heparin-like component had potent anti-factor Xa (40.7 U/mg) and anti-factor IIa (36.8 U/mg) activity, while the aortic component had anti-factor Xa (55.4 U/mg) and anti-factor IIa (11.3 U/mg) activity.

Conclusions:

• Heparin-like species from calf cerebral microvasculature possess significantly higher anticoagulant potency than those from the aorta.
• Anticoagulantly active components in the aorta are primarily localized within the intima.
• The highly active cerebral microvascular heparin-like species resembles heparan sulfate, while the aortic species resembles a heparin fragment.