title: Characterization of beta-adrenergic receptors in dispersed rat testicular interstitial cells.
abstract: Recent studies have shown that beta-adrenergic agents stimulate steroidogenesis and cyclic AMP formation in mouse Leydig cells in culture. To obtain information about the possible presence and the characteristics of a beta-adrenergic receptor in rat testicular interstitial cells, the potent beta-adrenergic antagonist [125I]cyanopindolol (CYP) was used as ligand. Interstitial cells prepared by collagenase dispersion from rat testis were incubated with the ligand for 2 h at room temperature. [125I]cyanopindolol binds to a single class of high affinity sites at an apparent KD value of 15 pM. A number of sites of 6,600 sites/cell is measured when 0.1 microM (-) propranolol is used to determine non-specific binding. The order of potency of a series of agonists competing for [125I]cyanopindolol binding is consistent with the interaction of a beta 2-subtype receptor: zinterol greater than (-) isoproterenol greater than (-) epinephrine = salbutamol much greater than (-) norepinephrine. In addition, it was observed that the potency of a large series of specific beta 1 and beta 2 synthetic compounds for displacing [125I]cyanopindolol in rat interstitial cells is similar to the potency observed for these compounds in a typical beta 2-adrenergic tissue, the rat lung. For example, the potency of zinterol, a specific beta 2-adrenergic agonist, is 10 times higher in interstitial cells and lung than in rat heart, a typical beta 1-adrenergic tissue. Inversely, practolol, a typical beta 1-antagonist, is about 50 times more potent in rat heart than in interstitial cells and lung.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive; D004837:Epinephrine / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000502:physiology; D007457:Iodine Radioisotopes; D007545:Isoproterenol / Q000378:metabolism; D007985:Leydig Cells / Q000648:ultrastructure*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013737:Testis / Q000166:cytology
chemical_list: D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta; D006165:Guanylyl Imidodiphosphate; C047975:cyanopindolol; D010869:Pindolol; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine