Biomaterial Database

Putative melatonin receptors in the male guinea pig kidney. 1993

Y Song, and A M Poon, and P P Lee, and S F Pang

Department of Physiology, Faculty of Medicine, University of Hong Kong.

The direct action of pineal melatonin on the renal system is supported by our demonstration of 2-[125I]iodomelatonin binding sites in the male guinea pig kidney. Scatchard analyses and Hill coefficients revealed a single type of binding site with an equilibrium dissociation constant (Kd) of 22.3 +/- 1.6 pmol/l and a maximum binding density (Bmax) of 0.99 +/- 0.03 fmol/mg protein (n = 7) at mid-light. There was no significant difference in the Kd and Bmax values between kidney tissues collected at the middle of light and dark periods. The pharmacological profile of these 2-[125I]iodomelatonin binding sites indicated high specificity for melatonin, 2-iodomelatonin and 6-chloromelatonin while kinetic studies generated a Kd value of 28.4 +/- 7.3 pmol/l (n = 5) which was comparable to that determined from Scatchard transformations. Our results suggest that these binding sites are stable, reversible, saturable, specific, and of high affinity. Regional distribution study showed that specific binding of 2-[125I]iodomelatonin was 8-fold higher in the cortical region than that in the medullary region. Studies of subcellular distribution showed that 59.3% of binding sites were localized in crude nuclear fractions followed by crude mitochondrial fractions (22.3%) and crude microsomal fractions (18.3%) with no detectable binding in cytosolic fractions. Our present findings suggest the presence of putative melatonin receptors in the guinea pig kidney, which support the hypotheses of melatonin-regulated renin secretion together with renal excretory functions via melatonin receptors.

UI	MeSH Term	Description	Entries
D007672	Kidney Cortex	The outer zone of the KIDNEY, beneath the capsule, consisting of KIDNEY GLOMERULUS; KIDNEY TUBULES, DISTAL; and KIDNEY TUBULES, PROXIMAL.	Cortex, Kidney
D007679	Kidney Medulla	The internal portion of the kidney, consisting of striated conical masses, the renal pyramids, whose bases are adjacent to the cortex and whose apices form prominent papillae projecting into the lumen of the minor calyces.	Kidney Papilla,Kidney Medullas,Kidney Papillas,Medulla, Kidney,Medullas, Kidney,Papilla, Kidney,Papillas, Kidney
D008297	Male		Males
D008550	Melatonin	A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013347	Subcellular Fractions	Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)	Fraction, Subcellular,Fractions, Subcellular,Subcellular Fraction