CGRP receptors mediating CGRP-, adrenomedullin- and amylin-induced relaxation in porcine coronary arteries. Characterization with 'Compound 1' (WO98/11128), a non-peptide antagonist.
1. Calcitonin gene-related peptide (CGRP), amylin and adrenomedullin (AM) belong to the same family of peptides. Accumulating evidence indicate that the calcitonin (CT) receptor, the CT receptor-like receptor (CRLR) and receptor-activity-modifying proteins (RAMPs) form the basis of all the receptors in this family of peptides. 2. Using reverse transcriptase - polymerase chain reaction the presence of mRNA sequences encoding the CRLR, RAMP1 and RAMP2 were demonstrated in porcine left anterior descending (LAD) coronary arteries, whereas porcine calcitonin (CT) receptor mRNA was not present. The partial porcine mRNA sequences shared 82 - 92% nucleotide identity with human sequences. 3. The human peptides alphaCGRP, betaCGRP, AM and amylin induced relaxation with pEC(50) values of 8.1, 8.1, 6.7 and 6.1 M respectively. 4. The antagonistic properties of a novel non-peptide CGRP antagonist 'Compound 1' (WO98/11128), betaCGRP(8 - 37) and the proposed AM receptor antagonist AM(22 - 52) were compared to the well-known CGRP(1) receptor antagonist alphaCGRP(8 - 37). 5. The alphaCGRP(8 - 37) and betaCGRP(8 - 37) induced concentration-dependent (10(-7) - 10(-5) M) rightward shift of both the alphaCGRP and betaCGRP concentration-response curves. betaCGRP(8 - 37) (10(-6) M) had the same effect as alphaCGRP(8 - 37) (10(-6) M), but with less potent rightward shift of the concentration-response curves for alphaCGRP, AM and amylin. 6. Preincubation with 'Compound 1' (10(-7) - 10(-5) M) and AM(22 - 52) (10(-6) M) had no significant antagonistic effect. 7. In conclusion, the building blocks forming CGRP and AM receptors were present in the porcine LAD, whereas those of the amylin receptor were not. alphaCGRP, betaCGRP, AM and amylin mediated vasorelaxation via the CGRP receptors. No functional response was detected to adrenomedullin via the adrenomedullin receptor.
Hasbak
P
P
Department of Clinical Experimental Research, University Hospital of Glostrup, Glostrup, Denmark. philip@post1.tele.dk
Sams
A
A
Schifter
S
S
Longmore
J
J
Edvinsson
L
L
D053607:Adrenomedullin; D000595:Amino Acid Sequence; D000682:Amyloid / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D015740:Calcitonin Gene-Related Peptide / Q000737:chemistry / Q000494:pharmacology*; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D003331:Coronary Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D058228:Islet Amyloid Polypeptide; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010879:Piperazines / Q000737:chemistry / Q000494:pharmacology*; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D058262:Receptor Activity-Modifying Protein 1; D058263:Receptor Activity-Modifying Protein 2; D058261:Receptor Activity-Modifying Proteins; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism; D013552:Swine; D014664:Vasodilation / Q000187:drug effects*
C425984:4-(2-oxo-2,3-dihydrobenzimidazol-1-yl)piperidine-1-carboxylic acid (1-(3,5-dibromo-4-hydroxybenzyl)-2-oxo-2-(4-phenylpiperazin-1-yl)ethyl)amide; D000682:Amyloid; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D047908:Intracellular Signaling Peptides and Proteins; D058228:Islet Amyloid Polypeptide; D008565:Membrane Proteins; D010446:Peptide Fragments; D010455:Peptides; D010879:Piperazines; D010880:Piperidines; C545502:RAMP1 protein, human; C545503:RAMP2 protein, human; D012333:RNA, Messenger; D058262:Receptor Activity-Modifying Protein 1; D058263:Receptor Activity-Modifying Protein 2; D058261:Receptor Activity-Modifying Proteins; D018015:Receptors, Calcitonin Gene-Related Peptide; D053607:Adrenomedullin; D015740:Calcitonin Gene-Related Peptide