Characterization of a peptide endothelium-derived constricting factor EDCF

Area of Science:

• Vascular Biology
• Endocrinology
• Biochemistry

Background:

• The endothelium regulates vascular tone through various mediators, including constrictors like endothelin.
• An additional cyclooxygenase-inhibitor-sensitive endothelium-derived constricting factor (EDCF) has been described, but its nature remains unclear.

Purpose of the Study:

• To elucidate the biochemical nature and release mechanism of the previously described EDCF.
• To characterize the molecular weight and functional properties of this novel constricting factor.

Main Methods:

• Bioassay using endothelium-denuded rabbit aortic segments to test eluates and supernatants from porcine aortic segments.
• Incubation of donor vessels with inhibitors (cycloheximide, quinacrine, indomethacine) to assess synthesis and release pathways.
• Molecular weight determination via ultrafiltration, gel filtration, and SDS-PAGE.
• Comparison with factors released from cultured porcine aortic endothelial cells (PAEC).

Main Results:

• A vasoconstrictive factor was released from porcine aortic segments, inducing sustained vasoconstriction in acceptor vessels.
• The factor was identified as a protein with an approximate molecular weight of 9,000 Da.
• Release was insensitive to cycloheximide but significantly reduced by quinacrine and indomethacine, suggesting dependence on cyclooxygenase and phospholipase A2 activity.
• The factor was not released from cultured PAEC.

Conclusions:

• A novel EDCF, distinct from endothelin, is luminally released from the endothelium.
• This EDCF is a peptide of approximately 9,000 Da that causes prolonged vasoconstriction.
• Its release or synthesis is dependent on cyclooxygenase and phospholipase A2 activity, leading to the proposed name PLA2-sensitive EDCF.