Acute effect of changes in renal arterial pressure and sympathetic blockade on kidney function

¹ Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi

The effect of varying the renal arterial pressure on kidney function has been studied before and after complete spinal anesthesia. It is concluded that an increase in renal arterial pressure between 60 and 300 mm Hg always results in an increase in renal blood flow, glomerular filtration rate and urine formation, and that filtration rate and urinary output are related to renal arterial pressure in a linear fashion at pressures above 120 mm Hg. Sympathetic blockade, accomplished by complete spinal anesthesia, resulted in a higher rate of urine formation and renal blood flow but not of glomerular filtration rate at each level of arterial pressure than before the spinal anesthesia was administered. Since the sympathetic blockade was not followed by an increase in glomerular filtration rate, it is concluded that the diuresis which followed this blockade resulted from a decrease in reabsorption of glomerular filtrate.