Journal of Applied Physiology

Published by American Physiological Society
Publications
Carbon dioxide labeled with oxygen 15 has been used to measure regional blood flow in the lung by counting over the chest during a short breath-holding period following a single breath of the gas. This gas has been found to exhibit different physiological behavior from carbon-11-labeled CO 2 . For example, the clearance rates of the oxygen-labeled gas are about twice as fast as those of carbon-labeled CO 2 . Measurements on alveolar gas expired immediately after inspiration of active gas show that the oxygen-labeled gas disappears from the alveoli about ten times faster than its carbon-labeled counterpart. In addition, if venous blood is drawn shortly after a breath of oxygen-labeled CO 2 , the activity cannot be removed from the blood by adding acid and shaking under vacuum, whereas the expected loss of activity occurs for carbon-labeled gas. These apparent discrepancies can be explained by exchange between the oxygen atoms of water and bicarbonate after the gas has been taken up by the blood. In vitro measurements show that the uptake of oxygen-labeled CO 2 into blood can be reduced by adding carbonic anhydrase inhibitor. The results affect the interpretation of the clearance rates of other radioactive gases in the lung. Submitted on December 7, 1960
 
The binding property of ionic indium (In3+) with plasma transferrin was utilized for determination of plasma volumes (PV) of whole body and individual organs in small animals. Plasma transferrin from a donor rat was labeled with 15-17 muCi 113mIn/ml plasma and injected into the tested rats. PV were determined either by extrapolation to the dilution at time zero (for whole animals) or by calculation of the ratio, organ radiation: radiation of a plasma unit volume (for organs). The reliability of the method for determination of whole-body PV was ascertained by comparing the results obtained with those obtained simultaneously by the Evans blue dilution method. Whole body PV values obtained by the two methods were similar, with a correlation coefficient (r) of 0.997. The short half life of 113mIn enables it to be used with other nuclides which have similar or different energies in the same sample; indium radiation was counted first and after it had disappeared the activity of the other nuclide could be measured.
 
Fourteen male Holstein-Fresian calves, 3–4 days of age, were placed on one of four diets for a 13-week experimental period. The diets included the following: milk and milk solids; milk and grain; milk, grain, and hay, inoculated (rumen ingesta from a mature steer introduced via stomach tube into the rumen of an experimental calf); or milk and grain, inoculated. Significant differences were noted in the effect of diet, age, and the interaction of diet and age on the fasting level of blood glucose. The calves on the diet containing milk and milk solids maintained a constant level of fasting blood glucose; however, the inclusion of grain and hay in the diet resulted in a decline of the fasting blood glucose. The rumen inoculation of one of the groups of calves on the milk and grain diet did not result in a fasting blood glucose which was statistically different from that of the calves not inoculated. ruminant blood glucose; diet and age interaction; milk solids Submitted on February 26, 1963
 
Values of PAH and Radio-Hippuran clearances, obtained simultaneously in 96 individual renal clearances for 16 patients, were plotted against each other and a regression line calculated which shows a linear relationship between the two substances. Knowing the value of the Radio-Hippuran clearance, by use of the regression line, the effective renal plasma flow in terms of PAH clearance can be estimated. This method of determination gives an accurate and less laborious measure of renal plasma flow than chemical determinations of PAH. Submitted on July 21, 1961
 
Radioiodinated diiodo-p-aminohippuric acid (DI ¹³¹ PAH) and N-(2,4-diiodo-3-hydroxyphenyl) urea (DI ¹³¹ HPU) were synthesized and examined for their potential usefulness in measuring the cardiac output in animals. These labeled compounds were injected intravenously into rats, rabbits and 13 dogs for study. The average rate of disappearance of DI ¹³¹ PAH from the blood stream of dogs was 50% and 90% in 1.0 and 6.9 minutes, respectively. Only a very small percentage of the injected radioactivity localized in the tissues, with approximately 0.5% in the thyroid at 24 hours. Under appropriate conditions of the experiment, more than 90% of the injected radioactivity was recovered in the excreta. Cardiac output values determined with DI ¹³¹ PAH on dogs were reproducible and in the range of reported values determined with other materials. Submitted on January 25, 1960
 
Tritiated and iodinated arginine vasopressin (AVP) were administered intravenously to human beings and to dogs. The level of plasma radioactivity was measured with time and showed a single exponential function in all cases, except with I ¹¹³ vasopressin in human beings, where two exponential components were evident. In the dog, the half-time for the disappearance of radioactivity from plasma ranged from 3.5 to 7 min after administration of I ¹¹³ AVP and from 4 to 5 min after H ³ AVP. In similar experiments in man, I ¹¹³ AVP gave a fast component with a half-time ranging from 0.3 to 2 min and a slow component with a half-time ranging from 1.6 to 6.5 min, whereas H ³ AVP gave a single component with a half-time ranging from 2.3 to 5.5 min. The similarity in the disappearance curve of antidiuretic activity and the disappearance curve of radioactivity suggests that the latter reflects the rate of degradation of the biologically active hormone. Therefore, these labeled hormones appear to be useful tools for evaluation of vasopressin turnover in physiological and clinical conditions alleged to be associated with increased levels of circulating antidiuretic hormone or with abnormal rates of vasopressin production, release, or inactivation. Submitted on March 9, 1961
 
We measured the steady-state volumes of distribution for radioactive chloride, sucrose, and albumin in the lung of six anesthetized, spen-thorax sheep. We allowed 2 days for [131I]albumin to equilibrate throughout the body, 2 h for the 36Cl, and a 40-min constant infusion for [14C]sucrose before killing the animal. Five minutes before death, we gave [125I]albumin to tag lung plasma volume. We killed the animals by clamping both lung hila; we then removed the lungs and homogenized them. We measured residual red cell and plasma volume, total extravascular lung water, and the extravascular content of the three tracers. The distribution volumes expressed as fractions of blood-free lung weight were: 36Cl equals 0.44, sucrose equals 0.28, and albumin equals 0.07. If the sucrose distribution volume is taken as the best estimate of the lung's extravascular extracellular space, then chloride clearly overestimates the interstitial fluid volume, being either bound or partially intracellular. On the other hand, albumin clearly underestimates the interstitial fluid volume.
 
A method is described which permits continuous estimation of adipose tissue blood flow (ATBF) in anesthetized female rats. The method is basesd on continuous monitoring of the elimination of 133Xe after labeling of the animal by intraperitoneal injection. From 2 to 6 h after the beginning of the elimination period close to 100% of the measured activity is shown to be located in adipose tissue, mainly in the parametrial fat. About 18% of the elimination is by way of intertissue diffusion, 82% of the perfusing blood. Changes in ATBF can readily be detected. The coefficient of variation for ATBF determinations is 9-11%. Changes in ATBF can be determined with great accuracy. Average ATBF per g tissue for fed and 48-h fasted rats were 0.105 and 0.122 ml-g-1-min-1, respectively. Total ATBF was lower in fasted than in fed rats (1.05 vs. 1.43 ml-min-1 for parametrial plus retroperitoneal fat). Intravenous administration of glucose (250 mg/h) decreased ATBF significantly in fed but not in fasted rats.
 
Top-cited authors
David L Costill
  • Ball State University
Karlman Wasserman
  • Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center
Björn Ekblom
  • Arizona School of Health Sciences
Giovanni Alfredo Cavagna
  • University of Milan
Solbert Permutt
  • Johns Hopkins Medicine