Osmolar ConcentrationGuanfacineIoxaglic AcidMannitolAdrenergic alpha-2 Receptor AntagonistsDiuresisHypertonic SolutionsAdrenergic alpha-2 Receptor AgonistsNaltrexonePrazosinIdazoxanQuinoxalinesAdrenergic alpha-AgonistsKidneyContrast MediaBlood Urea NitrogenReceptors, Adrenergic, alpha-2SodiumSodium ChlorideNatriuresisGlomerular Filtration RateAdrenergic alpha-AntagonistsWaterPotassiumRats, Sprague-Dawley