Design and synthesis of a specific endothelin 1 antagonist: effects on pulmonary vasoconstriction.
The 21-amino acid vasoconstrictor peptide endothelin (Et) contains two disulfide bonds. We investigated the importance of the outer disulfide bond in Et-1 by replacing it with an amide linkage. Bioactivity was assessed in an isolated guinea pig lung preparation (perfused at constant flow with Ringer's solution/0.5% albumin) in which pulmonary artery pressure was monitored. Et-1 produced concentration-dependent pulmonary vasoconstriction at concentrations of 1 x 10(-10) M and higher. [Dpr1, Asp15]Et-1 (where Dpr is diaminopropionic acid), in which the outer disulfide was replaced by an amide bond and the inner disulfide was left intact, showed no agonist activity at 1 x 10(-6) M but 1 x 10(-7) M [Dpr1, Asp15]Et-1 inhibited Et-1-induced pulmonary vasoconstriction: effects of 1 x 10(-10) M 2 x 10(-10) M, and 1 x 10(-9) M Et-1 were inhibited by 98%, 75%, and 65%, respectively. Furthermore, this analog did not alter pulmonary vasoconstriction induced by thrombin, norepinephrine, or, most significantly, Et-3. A monocyclic Et-1 analog with the same sequence but in which the amide bond was not formed showed weak pulmonary vasoconstrictor activity (300-500 times less potent than Et-1) but had no antagonist activity. In addition, both the monocyclic control peptide and [Dpr1, Asp15]Et-1 competed effectively with 125I-labeled Et-1 for binding to cultured rat pulmonary artery smooth muscle cells. Thus, an Et-1 structural analog produced by replacement of the outer disulfide bond with an amide linkage displayed potent and specific Et-1 antagonism.
Spinella
M J
MJ
Department of Biochemistry and Molecular Biology, Albany Medical College of Union University, NY 12208.
Malik
A B
AB
Everitt
J
J
Andersen
T T
TT
D000595:Amino Acid Sequence; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002478:Cells, Cultured; D004220:Disulfides; D015195:Drug Design; D016232:Endothelins / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D011487:Protein Conformation; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000138:chemical synthesis*
D004220:Disulfides; D016232:Endothelins; D010455:Peptides; D014662:Vasoconstrictor Agents