title: 3h-substance P binding to salivary gland membranes. Regulation by guanyl nucleotides and divalent cations.
abstract: With appropriate measures to protect 3H-substance P (3H-SP) from proteolytic degradation and from nonspecific adsorption to glass-fiber filters, we have been able to demonstrate reliably a high-affinity specific binding of 3H-SP to rat submaxillary/sublingual gland membranes with a KD of 1 nM and Bmax of 6 pmoles/g of tissue. The relative potencies of various SP fragments and related analogues in reducing 3H-SP binding parallel their potencies in stimulating phosphatidylinositol turnover, amylase release, and salivation, thus supporting an association of the observed 3H-SP binding site with the physiological SP receptors in this tissue. This binding is selectively stimulated by some divalent cations (Mn2+ greater than Mg2+ greater than Ca2+) but inhibited by several guanyl nucleotides, suggesting a possible linkage to adenylate cyclase. However, no effect of SP on either the basal or the norepinephrine-stimulated adenylate cyclase activity could be demonstrated in salivary gland homogenates.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002413:Cations, Divalent; D002462:Cell Membrane / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018040:Receptors, Neurokinin-1; D013361:Sublingual Gland / Q000378:metabolism*; D013363:Submandibular Gland / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D011956:Receptors, Cell Surface; D018040:Receptors, Neurokinin-1; D013373:Substance P; D006165:Guanylyl Imidodiphosphate; D006160:Guanosine Triphosphate; D000262:Adenylyl Cyclases