Table 2.

Relative binding affinities of GHRH-related peptides to membrane receptors for GHRH and VIP on rat anterior pituitary and pineal cells

Peptide	Relative affinity to pituitary GHRH-R*	Relative affinity to pituitary VPAC-R†	Relative affinity to pineal VPAC-R‡
hGHRH(1-29)NH2	1	<0.001	N/A
VIP	<0.001	1	1
JV-1-36	79	<0.01	N/A
JV-1-38	42	<0.01	<0.001
JV-1-50	0.2	<0.01	N/A
JV-1-51	0.08	0.4	N/A
JV-1-52	0.2	0.8	N/A
JV-1-53	<0.001	1.1	1.9
PG 97-269	<0.001	<0.001	0.9

Binding affinities were determined by using a nonlinear curve fitting program (33) for analysis of ligand competition studies, as described. Values represent mean of duplicate determinations. N/A, data not available. 

^*Expressed relative to the binding affinity of hGHRH(1-29)NH₂ to rat pituitary GHRH-R (K_i = 3.34 nM). 

^† Expressed relative to the binding affinity of VIP to rat pituitary VPAC-R (K_i = 1.13 nM). 

^‡ Expressed relative to the binding affinity of VIP to rat pineal VPAC-R (K_i = 16.4 nM).