Renal Blood Flow, Glomerular Filtration Rate, Renal PAH Extraction Ratio, and the Role of the Renal Vasomotor Nerves in the Unanesthetized Rabbit

The unanesthetized rabbit has been found to be a satisfactory animal for studying the renal circulation. Techniques for measuring renal clearances and cardiac output, for carrying out renal vein catheterization, and for measuring renal clearances separately for each kidney are described. Normal values are presented from data obtained from 86 rabbits. Renal blood flow and glomerular filtration rate were found to be stable, judged by the reproducibility of these measurements over a period of three hours. Renal PAH extraction ratios averaged 95.5% in 16 unanesthetized animals. In 12 animals renal blood flow was 6% higher in one chronically denervated kidney than in the contralateral innervated kidney, indicating a low degree of sympathetic vasoconstriction in the normal resting circulation of the rabbit. All the results were obtained in the rabbit in the course of moderate water and mannitol diuresis.