title: Renal handling and acute urinary electrolyte effects of aminoglycoside antibiotics: use of a solitary renal autotransplant in the conscious sheep.
abstract: Renal handling of the aminoglycoside antibiotics gentamicin and tobramycin were studied before and after one hour of constant intravenous infusions adjusted to maintain a concentration of 15 micrograms/mL. A solitary renal autotransplant model in four conscious volume replete 40 Kg sheep was used. This unique surgical preparation allows sampling of renal arterial and renal venous blood as well as urine drained through an exteriorized parotid-ureteral fistula. This surgical preparation has considerable potential in renal pharmacology since it uses a conscious, large animal. Baseline studies in this preparation demonstrated normal, 51CrEDTA and 125 I PAH, clearances which were unaffected by the drugs. Aminoglycoside binding to pooled sheep sera was 11% at physiologic PH, calcium and magnesium concentrations. A-V difference was 1.3 +/- .3 micrograms/mL and extraction by the kidney was 9 +/- 3.2% with no differences between gentamicin and tobramycin. Clearance of gentamicin was 84% and tobramycin 86% of GFR. There was no evidence of tubular injury as evidenced by unchanged urinary beta-2 microglobulin excretion. Serum Na, K, Ca and Mg did not change over the course of the study. Both drugs caused a prompt decrease in absolute and fractional sodium excretion while only gentamicin produced a kaliuresis. Early aminoglycoside effects on electrolyte balance may be an eventual determinant of nephrotoxic potential rather than differences in renal drug handling.
mesh_terms: D000617:Aminoglycosides / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D004573:Electrolytes / Q000097:blood; D005839:Gentamicins / Q000378:metabolism; D005919:Glomerular Filtration Rate; D007668:Kidney / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D012756:Sheep; D014031:Tobramycin / Q000378:metabolism
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004573:Electrolytes; D005839:Gentamicins; D014031:Tobramycin