Abstract
Calcitonin gene-related peptide (CGRP), a potent vasodilatory and cardiotonic peptide, has a potential role for CGRP in diverse physiologic and pathophysiologic situations such as congestive heart failure, diabetes, migraine, and neurogenic inflammation. Although a peptide CGRP receptor antagonist, CGRP8-37, is available, its utility presents significant limitations for these indications. Here, we describe the properties of SB-(+)-273779 [N-methyl-N-(2-methylphenyl)-3-nitro-4-(2-thiazolylsulfinyl)nitrobenzanilide], a selective nonpeptide antagonist of CGRP1 receptor. SB-(+)-273779 inhibited 125I-labeled CGRP binding to SK-N-MC (human neuroblastoma cells) and human cloned CGRP1receptor with Ki values of 310 ± 40 and 250 ±15 nM, respectively. SB-(+)-273779 also inhibited CGRP (3 nM)-activated adenylyl cyclase in these systems with IC50values of 390 ±10 nM (in SK-N-MC) and 210 ±16 nM (recombinant human CGRP receptors). Prolonged treatment (>30 min) of SK-N-MC cells with SB-(+)-273779 followed by extensive washing resulted in reduction in maximum CGRP-mediated adenylyl cyclase activity, suggesting that this compound has irreversible binding characteristics. In addition, SB-(+)-273779 antagonized CGRP-mediated 1) stimulation of intracellular Ca2+ in recombinant CGRP receptors in HEK-293 cells, 2) inhibition of insulin-stimulated [14C]deoxyglucose uptake in L6 cells, 3) vasodilation in rat pulmonary artery, and 4) decrease in blood pressure in anesthetized rats. SB-(+)-273779 tested at 3 μM had no significant affinity for calcitonin, endothelin, angiotensin II, and α-adrenergic receptors under standard ligand binding assays. SB-(+)-273779 also did not inhibit forskolin and pituitary adenylate cyclase-activating polypeptide. These results suggest that SB-(+)-273779 is a valuable tool for studying CGRP-mediated functional responses in complex biological systems.
Footnotes
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Send reprint requests to: Nambi Aiyar, Ph.D., SmithKline Beecham, Dept. of CV Pharmacology, UW2510, 709 Swedeland Rd., Box 1539, King of Prussia, PA 19406-0939. E-mail:Nambi_Aiyar-1{at}sbphrd.com
- Abbreviations:
- CGRP
- calcitonin gene-related peptide
- hαCGRP
- human αCGRP
- hαCGRP8-37
- human αCGRP8-37
- SB-(+)-273779
- N-methyl-N-(2-methylphenyl)-3-nitro-4-(2-thiazolylsulfinyl)nitrobenzanilide
- SB-268262
- thiazolylsulfoxide nitrobenzanilide
- BIBN 4096BS
- (1-piperidinecarboxamide,N-[-2-[[5-amino-1-[[4-(4-pyridinyl)-1-piperazinyl]carbonyl]pentyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl)-)
- DMSO
- dimethyl sulfoxide
- [Ca2+]i
- intracellular calcium concentration
- SK-N-MC
- human neuroblastoma cells
- HEK
- human embryonic kidney
- MEM
- minimal essential medium
- Received August 3, 2000.
- Accepted October 27, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
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