Interaction of vasoactive intestinal peptide (VIP) with rat lymphoid cells.
Receptors for vasoactive intestinal peptide (VIP) have been characterized in rat lymphoid cells. The interaction of [125I] VIP with blood mononuclear cells was rapid, reversible, specific and saturable. At apparent equilibrium, the binding of [125I] VIP was competitively inhibited by native VIP in the 0.01-100 nM range concentration. The binding data were compatible with the existence of two classes of receptors: a high-affinity class with a Kd = 0.050 +/- 0.009 nM and a low binding capacity (2.60 +/- 0.28 fmol/10(6) cells), and a low-affinity class with a Kd = 142 +/- 80 nM and a high binding capacity (1966 +/- 330 fmol/10(6) cells). Secretin, glucagon, insulin and somatostatin did not show any effect at a concentration as high as 100 nM. With spleen lymphoid cells, stoichiometric studies were performed. The binding data were compatible with the existence of two classes of receptors: a high-affinity class with a Kd = 0.100 +/- 0.033 nM and a low binding capacity (4.60 +/- 1.07 fmol/10(6) cells), and low-affinity class with a Kd = 255 +/- 110 nM and high binding capacity (2915 +/- 1160 fmol/10(6) cells). With thymocytes, no binding was obtained under different conditions.
D000818:Animals; D001667:Binding, Competitive; D007700:Kinetics; D008214:Lymphocytes / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide / Q000097:blood*
D011956:Receptors, Cell Surface; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide