0.003 and 0.01 mg/ kg

Female New Zealand White rabbits renal proximal tubular cells (RPTC) were isolated using the iron oxide perfusion method and grown in 35-mm tissue culture dishes. The culture medium was a 1:1 mixture of Dulbecco’s modified Eagle’s medium/Ham’s F-12 (without glucose, phenol red, or sodium pyruvate) supplemented with 15 mM HEPES buffer, 2.5 mM L-glutamine, 1 mkM pyridoxine HCl, 15 mM sodium bicarbonate, and 6 mM lactate. Hydrocortisone (50 nM), selenium (5 ng/ml), human transferrin (5 mkg/ml), bovine insulin (10 nM), and L-ascorbic acid-2-phosphate (50 mkM) were added daily to fresh culture medium. RPTC monolayers were treated with either the pan-5-HT receptor antagonist AM-193 (Spiramide) (10 mkM) or vehicle control (dimethyl sulfoxide) for 30 min and then exposed to DOI (10 mkM) for 12 h.