ABSTRACT
Previous studies have demonstrated that pretreatment with mannitol, furosemide, or bradykinin can attenuate the severity of norepinephrine-induced renal functional impairment. The present studies were designed to evaluate the possibility that these agents are protective, in part, by preserving cellular metabolic integrity. The renal cortex was repetitively biopsied during the course of this study, and high-pressure liquid chromatography was used to analyze the tissue content of adenine nucleotides (expressed in nanomoles per gram of wet tissue). The adenine nucleotide charge ratio (CR) and total adenine nucleotide (TAN) content were calculated as indices of cellular metabolic integrity. In addition to the above-established protective agents, phenoxybenzamine was used to evaluate a direct toxic effect of norepinephrine on renal tissue. Inulin clearance at 3 hours post infusion (expressed as a percent of control) was 7% with norepinephrine alone and, in the protected groups, 36% with bradykinin, 61% with furosemide, 51% with mannitol, and 100% with phenoxybenzamine. There was no change in CR or TAN with phenoxybenzamine. In contrast, during norepinephrine administration CR fell significantly in all other groups. Three hours after stopping norepinephrine, CR had returned toward control values and the level of CR was significantly better in all protected groups when compared with norepinephrine alone. Similarly, the levels of TAN were significantly diminished in the norepinephrine-alone group when compared to all protected groups, and there was significantly more tubular necrosis as well. The maintenance of higher levels of TAN and the preserved ability to regenerate adenosine triphosphate in the protected groups, when compared to the norepinephrine-alone group, support the contention that these agents offer protection, at least in part, by preserving cellular metabolic integrity.
