Injection of meglumine diatrizoate (Renografin-76) into the selectively perfused sinus node artery of the dog produces bradycardia which is unaltered by autonomic blockade or by changes in sinus node artery pressure. Contrast agents and other hyperosmolar substances prolong the R-R interval in proportion to their osmolarity. Selective injection of contrast media into other cannulated segments of the coronary tree produces no change in heart rate. Transfemoral arteriography, however, produces bradycardia with both right and left coronary injections. Both direct and reflex sinus node depression occur with coronary arteriography in the dog. Direct effects are mediated by hyperosmolarity.
To measure blood flow through fast and slow pathways of the kidney separately, a new method of analyzing dye-dilution curves was devised. Twenty-five patients with hypertension or renal disease were selected for study. Indocyanine green was injected into one renal artery and dye-dilution curves were recorded in blood from the ipsilateral renal vein, using a densitometer. Recirculation effect was eliminated by the curve obtained from the contralateral renal vein. For analyzing the dyedilution curves, a new mathematical model and an iterative least squares method of fitting the curve using a digital computer were employed. Basic assumption for the model was that the transit time of each molecule of the dye through fast and slow pathways was a random variable and followed a log-normal distribution. The fast flow measured by the new method was significantly decreased in 11 patients with azotemia compared with that in 14 without azotemia, while changes in slow flow were not significant. Consequently, the ratio of the slow flow to the total flow was increased in renal failure.
SUMMARYIn order to study the distribution of blood flow in diseased human kidneys, Xe133 washout curves were obtained from 34 patients with chronic renal disease or hypertension.The curves recorded for over 45 min. were resolved into 4 components, while the curves recorded for 30 min. showed 3 components. The values of components I, II and III in the 30 min. record coincided with those of the components I, the average of II and III, and IV in the 45 min. record, respectively.The percentage of the total renal blood flow (flow ratio) distributed to the component I of the 30 min. record was correlated with that due to cortical blood flow as determined by the dye-dilution method. It is suggested that the component I of the Xe133 washout curve from the human kidney represents the cortical blood flow.The results obtained from the Xe133 washout curves recorded for 30 min. were compared with the renal function of the patients. The flow for unit mass of tissue (flow rate) and the flow ratio of the fastest component (component I) were decreased in the azotemics. The flow rate of component I was also decreased in proportion to the reduction of the RBF calculated from CPAH (RBFPAH), GFR from CThio and maximal urinary osmolality, while the flow rate of component II did not change significantly. As the renal function became impaired to the level of RBFPAH less than 500ml./min., GFR 50ml./min. and maximal urinary osmolality 700mOsm, the flow ratio of component I decreased and that of component II increased progressively. AdditionalIndexing Words:Xe133 washout method Dye-dilution method Blood flow for unit mass of tissue (flow rate)Percentage of total renal blood flow (flow ratio) Chronic ranal failure
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