Effect of levarterenol on renal blood flow and vascular volume in dogs

¹ Departments of Physiology and Pharmacology, Medical College of Georgia, Augusta, Georgia

T-1824 was injected quickly into the renal artery of dogs and the renal vein stream was divided into samples every second. From the analysis of these timed samples a dye concentration curve was plotted and the flow and mean transit time were calculated. Since the flow calculated from the area of this curve agreed closely with the flow measured in the sampling tubes it was assumed that all the injected dye was recovered and that the mean transit time multiplied by the flow equaled the capacity of the active vascular channels. In seven animals the infusion of levarterenol produced an increase in renal vascular resistance without curtailing renal blood flow to such a degree that the dye curve could not be plotted. In these animals the arterial pressure rose, on the average from 109 to 176 mm Hg. This change in resistance reduced the renal blood flow from 120 to 84 cc/min., increased the mean transit time from 7.5 to 13.9 seconds and increased the volume of actively flowing blood from 15 to 17 cc (from 30 to 34 cc/100 gm of kidney). From these experiments it is concluded that the classical renal swelling from injection of epinephrine is the result of an increase in the resistance of post capillary segments of the renal vasculature and a distention of glomerular and possibly of peritubular capillaries.