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Culturing Primary Rat Inner Medullary Collecting Duct Cells
Published on: June 21, 2013
Characterization of a growth hormone-releasing hormone binding site in the rat renal medulla
Luce Boulanger1, Nathalie Girard, Julie Strecko
1Laboratory of Neuroendocrinology of Aging, Department of Medicine, CHUM Research Center, Notre-Dame Hospital, University of Montreal, 1560 East Sherbrooke Street, Que., H2L 4M1, Montreal, Canada.
Abstract:
Receptor binding analysis was performed in the renal medulla from 2-month-old rats, an extrapituitary tissue containing the highest level of GHRH receptor mRNA. At 4 degrees C, in the presence of a cocktail of protease inhibitors, binding of [125I-Tyr(10)]hGHRH (1-44)NH(2) to medullary homogenates was specific, time-dependent, reversible and saturable (K(d): 28 nM; B(max): 30 fmol/mgprot.). In these experimental conditions, no change of binding parameters could be detected in the course of aging. The structure-affinity profile was different in the two tissues and chemical cross-linking revealed the presence of 65-, 55- and 38-kDa 125I-GHRH-labeled complexes in the renal medulla compared to 65-, 47- and 28-kDa radioactive complexes in the anterior pituitary. It is suggested that GHRH binding sites, and possibly the receptor, may be different in the two tissues.
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