Please use this identifier to cite or link to this item:
https://ahro.austin.org.au/austinjspui/handle/1/13632
Title: | [3H]Rilmenidine-labelled imidazoline-receptor binding sites co-localize with [3H]2-(benzofuranyl)-2-imidazoline-labelled imidazoline-receptor binding sites and monoamine oxidase-B in rabbit, but not rat, kidney. | Austin Authors: | King, P R;Suzuki, Satoshi;Hosseini, A R;Iakovidis, D;Nero, Tracy L;Jackman, G P;Louis, William J ;Gundlach, Andrew L | Affiliation: | The University of Melbourne, Department of Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia | Issue Date: | 15-Oct-1998 | Publication information: | Journal of the Autonomic Nervous System; 72(2-3): 118-28 | Abstract: | The distribution and relative densities of imidazoline-receptor binding sites (I-RBS) and monoamine oxidase (MAO)-A and -B enzyme(s) in rat and rabbit kidney were compared autoradiographically using fixed nanomolar concentrations of [3H]rilmenidine and [3H]2-(benzofuranyl)-2-imidazoline ([3H]2-BFI) to label I-RBS, and [3H]RO41-1049 and [3H]RO19-6327 to label MAO-A and -B isoenzymes, respectively. In rat kidney, high densities of I-RBS labelled by [3H]rilmenidine were observed in the cortex and outer stripe (120-280 fmol/mg tissue), in contrast to low I-RBS densities labelled by [3H]2-BFI (<4 fmol/mg). A relatively high density of [3H]RO41-1049 binding to MAO-A enzyme was present in all regions of the rat kidney (160-210 fmol/mg) compared with a low density of [3H]RO19-6327 binding to MAO-B (< 25 fmol/mg). Comparison of MAO-A and -B distributions with that of [3H]rilmenidine-labelled I-RBS strongly suggests a lack of association in rat kidney. Similarly, the extremely low densities of [3H]2-BFI-labelled I2-RBS in rat kidney contrasts with the density of MAO-A, but is consistent with the low density of MAO-B. Rabbit kidney cortex and outer stripe contained high relative densities of [3H]rilmenidine-labelled I-RBS (200-215 fmol/mg) and [3H]2-BFI-labelled I2-RBS (45-60 fmol/mg) with lower densities in the inner stripe and inner medulla (< or = 100 and 30 fmol/mg respectively). A high density of MAO-A binding was observed in the inner stripe (515 fmol/mg) with lower levels in the cortex and outer stripe (100-240 fmol/mg), while high densities of MAO-B binding were observed in the cortex and outer stripe (290-450 fmol/mg) with lower levels in the inner stripe (65 fmol/mg). The correlation between the localization of [3H]rilmenidine-labelled I-RBS and [3H]RO19-6327-labelled MAO-B in rabbit kidney (r = 0.87, P = 0.057) suggest that [3H]rilmenidine may label a binding site co-existent with MAO-B, but not MAO-A (n.s.), in this tissue, but rilmenidine did not inhibit [3H]RO41-1049 or [3H]RO19-6327 binding. The distribution of [3H]2-BFI-labelled I2-RBS overlapped the combined distributions of both MAO-A and -B isoenzymes, suggesting that [3H]2-BFI may label sites on both enzymes in the rabbit, but [3H]2-BFI binding only correlated with [3H]RO19-6327 (r = 0.84, P = 0.07), not [3H]RO41-1049 binding (n.s.). Moreover, 2-BFI only inhibited [3H]RO19-6327, not [3H]RO41-1049 binding. These data are consistent with reports that I2-RBS are located on MAO-B and allosterically influence the catalytic site. The relationship of [3H]rilmenidine- and [3H]2-BFI-labelled I-RBS and the identity of non-MAO-associated [3H]rilmenidine-labelled I-RBS requires further investigation. | Gov't Doc #: | 9851560 | URI: | https://ahro.austin.org.au/austinjspui/handle/1/13632 | Journal: | Journal of the autonomic nervous system | URL: | https://pubmed.ncbi.nlm.nih.gov/9851560 | Type: | Journal Article | Subjects: | Adrenergic alpha-Agonists.metabolism Animals Autoradiography Benzofurans.metabolism Imidazoles.metabolism Imidazoline Receptors In Vitro Techniques Isoenzymes.metabolism Kidney.enzymology.metabolism Male Monoamine Oxidase.metabolism Monoamine Oxidase Inhibitors.metabolism Oxazoles.metabolism Picolinic Acids.metabolism Rabbits Rats Rats, Inbred WKY Receptors, Drug.metabolism Species Specificity Thiazoles.metabolism |
Appears in Collections: | Journal articles |
Show full item record
Items in AHRO are protected by copyright, with all rights reserved, unless otherwise indicated.