title: Pharmacologic identification of putative D1 dopamine receptors in feline kidneys.
abstract: The presence of dopamine (DA) receptors in feline kidneys is a matter of contention. Radioligand binding and Western blotting studies were employed to determine whether DA receptors are present in feline kidneys. The pharmacologic profile of the selective D1-receptor antagonist [3H]-SCH 23390 was studied in renal cortical membrane preparations from cats by conducting saturation binding isotherm and competitive binding experiments. [3H]-SCH 23390 bound to feline renal cortical membranes in a manner consistent with labeling of a D1-like receptor. The binding profile revealed a single site D1-like or D1 receptor in the feline renal cortex with a Kd = 7.8 +/- 1.0 nmol/L and Bmax = 76.5 +/- 19.5 fmol/mg. Competitive binding studies for [3H]-SCH 23390 against unlabeled agonists yielded the following Ki values and rank order of competition: SKF38393 (Ki = 0.47 +/- 0.26 micro m) > fenoldopam (Ki = 3.12 +/- 1.1 micro m) > DA (Ki = 933.1 +/- 1.6 micro m). Competitive binding studies for [3H]-SCH-23390 against unlabeled antagonists yielded the following rank order of competition: SCH 23390 (Ki = 1.97 +/- 0.81 micro m) > spiperone (Ki = 3.79 +/- 0.79) > metoclopramide (Ki = 4.26 +/- 2.4 micro m). Western blot analysis with anti-DA D1 receptor antibodies detected a single band with Mr of 74 kDa corresponding to a D1 DA receptor. These results suggest that a putative D1-like or D1 receptor exists in feline kidneys different from those previously identified in rat, dog or human kidneys.
authors.affiliation: Walter Reed Army Institute of Research, Washington DC, USA.
authors.forename: W S
authors.initials: WS
authors.lastname: Flournoy
authors.forename: J S
authors.initials: JS
authors.lastname: Wohl
authors.forename: T J
authors.initials: TJ
authors.lastname: Albrecht-Schmitt
authors.forename: D D
authors.initials: DD
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D015153:Blotting, Western; D002415:Cats / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D007668:Kidney / Q000502:physiology*; D008024:Ligands; D017447:Receptors, Dopamine D1 / Q000032:analysis / Q000187:drug effects / Q000502:physiology*
chemical_list: D018492:Dopamine Antagonists; D008024:Ligands; D017447:Receptors, Dopamine D1