Osmolar ConcentrationGuanfacineIoxaglic AcidMannitolAdrenergic alpha-2 Receptor AntagonistsDiuresisHypertonic SolutionsAdrenergic alpha-2 Receptor AgonistsCentrifugation, Density GradientNaltrexonePrazosinIdazoxanQuinoxalinesAdrenergic alpha-AgonistsSodiumKidneyContrast MediaBlood Urea NitrogenSodium ChlorideReceptors, Adrenergic, alpha-2NatriuresisGlomerular Filtration RateWaterPotassiumAdrenergic alpha-AntagonistsDenaturing Gradient Gel ElectrophoresisRats, Sprague-DawleyHydrogen-Ion ConcentrationCell FractionationCentrifugation, IsopycnicModels, BiologicalKineticsChemotaxisMetrizamideDiffusionBiological TransportElectrophoresis, Polyacrylamide GelBiological Transport, Active