Table 1

K_I values of CGRP analogs in pig coronary arteries and in pig CGRP₁ receptor-transfected HEK 293 cells

Ligand	Pig Coronary Arteries		Transfected CGRP₁ Receptor
Ligand	K_I	Hill Slope^1-a	K_I	Hill Slope^1-a
	nM		nM
hα-CGRP	0.11 ± .08	−0.94	0.08 ± 0.01	−0.85
[N-benzoyl]hα-CGRP_8–37	0.27^1-b		0.072 ± 0.006	−0.96
[N-acetyl]hα-CGRP_8–37	1.3 ± 0.8	−0.82	1.3 ± 0.05	−0.82
hα-CGRP_8–37	6.6 ± 6.3	−0.90	5.7 ± 1.7	−0.84
[Pro¹⁴]hα-CGRP	9.0 ± 6.3	−0.70	5.5 ± 1.3	−0.80
[D-Pen^2,7]hα-CGRP	21.0 ± 5.9	−0.93	15.2 ± 2.7	−0.95
Adrenomedullin	19.9 ± 11.6	−0.97	19.9 ± 12.9	−0.80
[Cys(ACM)^2,7]hα-CGRP	38.4 ± 25.2	−0.81	32.0 ± 5.8	−0.82
[Cha³⁷]hα-CGRP_8–37	32.7 ± 13.6	−0.96	37.9 ± 4.3	−0.90
[Pro³⁴,Phe³⁵]hα-CGRP_27–37	50.7 ± 16.7	−1.05	118.2 ± 40.2	−1.10
[Ala³⁷]hα-CGRP_8–37	499.9 ± 265	−1.00	1021 ± 200	−0.53
Calcitonin	No binding		No binding

Each value represents the mean ± S.E.M. of three to five separate membrane preparations, each from a different pig or from a different group of cells. A two-tailed t test of pK_I values found no significant differences (p < 0.05) for any of these peptides when comparing their affinities for membranes from pig coronary arteries to their affinities for membranes from the pig CGRP₁ receptor clone.

↵1-a The 95% confidence intervals of the Hill slope included the value of −1.0 for each ligand except for h-αCGRP_8–37, [Pro¹⁴]h-αCGRP, [Ala³⁷]h-αCGRP_8–37, and adrenomedullin in the pig CGRP₁ receptor clone.
↵1-b From Smith et al. (2001).