ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. The distribution and binding characteristics of the radioligand (-)-[125I]-cyanopindolol (CYP) have been examined in slide mounted mouse kidney sections, using the technique of in vitro labelling and autoradiography.2. (-)-[125I]-CYP binding to sections was of high affinity (KD=55.8 pmol/l, s.e.m. = 8. 1, n= 4) to a single population of non-interacting sites (nH = 0. 95, s.e.m. = 0. 01, Bmax= 0.74 fmol/section, s.e.m. = 0. 12, n= 4) and stereoselective with respect to the (-)- and (+)-isomers of both propranolol and pindolol.3. Autoradiographic studies showed that (-)-[125I]-CYP binding was localized to areas in the renal cortex and medulla. Both cortical and medullary binding were abolished by the inclusion of (-)-propranolol (1 μmol/l) in the incubation medium, whereas (-)-isoprenaline (200 μmol/l) selectively abolished cortical binding.4. Medullary binding could be prevented by the inclusion of the lipophilic compounds cinanserin (10 μmol/l), haloperidol (10 μmol/l) or phentolamine (10 μmol/l), either alone or together or by washing at 37°C. These results suggest that medullary binding sites are lipid rather than receptor-related.5. In conclusion, in mouse kidney sections, (-)-[125I]-CYP binds to discrete areas in the cortex and medulla. Cortical binding sites have the molecular characteristics of β-adrenoceptors while medullary binding sites are lipid-related. Caution should therefore be exercised when defining non-specific binding of lipophilic radioligands. The autoradiographic technique is useful for discriminating between receptor and non-receptor binding sites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1986.tb00339.x
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