No abstract

No abstract

"4 have been comprehensively reviewed by Page and Bumpus. 5 Although the literature is replete with information on its overall pressor properties and its effects on the cardiac output, the effects of angiotensin on regional blood flow and organ vascular resistance have not been adequately evaluated for most regions. Observations on the regional effects of angiotensin have been confined to a few organs or areas. As will be shown in the Discussion, the results are not always consistent in different preparations, and little information is available in the intact animal.A method developed in the Department of Physiology at Ohio State University 0 allows the measurement of the distribution of the cardiac output to all organs simultaneously in the intact animal. The present report is concerned with the application of this method to the determination of regional blood flow and regional vascular resistance in rats anesthetized with sodium pentobarbital and infused with varying doses of angiotensin. MethodsTwo hundred and eleven female rats of the Sprague-Dawloy strain which had been fasted for 18 hours were used in these studies. Of these, 75 (51 control, 24 experimental) were used in blood From the Department of Physiology, Ohio State Univevsity, Columbus, and Aerospace Medical Laboratory, Wright Patterson Air Force Base, Ohio.This work was supported by grants-in-aid from the American Heart Association and the Central Ohio Heart Association. Support was also received from Grunt H-4730 from the National Heart Institute, U. S. Public Health Service.Dr. Mandol is a Captain (MC) in the United States Air Force. The opinions expressed in this paper are those of the authors and do not necessarily represent the views of the United States Air Force.Received for publication November 27, 1961. pressure measurements; 38 (10 control, 2S expei'iniental) were employed in cardiac output measurements; regional flow distribution for all organs other than the brain was measvii'ed in 71 (22 control, 49 experimental), and cerebral flow fraction was measured in 102 (37 control, 65 experimental). Water wns allowed ad libitum. The animals weighed between 190 and 250 Gm. Sodium pentoharbital (40 mg./Kg., intraperitoneally) was used as the anesthetic. Angiotensin 0 was infused into the femoral vein by means of a Harvard infusion pump for 5 to 25 minutes at 0.05 ml./niin. of solution containing concentrations of angiotensin sufficient to yield 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5 /i.g./Kg. body weight/min.Mean arterial pressures were measured from the femoral artery in heparinized rats with a mercury manometer connected to the artery by a 25-or 27-gauge needle. The same animals were also used for either the cardinc output or the regional flow determination. Cardiac outputs were measured by the indicator-dilution technique, using Rb 80 as the indicator. The rate of sample collection was 60/tnin. Because of the hemorrhage produced by the cardiac output determination, different animals were used for regional blood flow studies.Distribution of blood flo...

The indicator-fractiomition technic for measurement of regional blood flow has been applied to the measurement of blood flow in the aortic wall, using Rb S(i . The aorticindicator content declines slowly with time during the first minute, which shows that the aorta has a smaller extraction ratio for Rb sti than the rest of the body. The application of the indieator-fractionation teehnic when organ content of indicator changes with time is discussed. It is shown that the perfusion rate of rat aorta is at least 1.70 ml./Gm./min. This value is much larger than would be expected from in vitro studies of aortic oxygen utilization.

Rb86 and Iodo131 antipyrine were injected together by vein in rats. The brain, spinal cord, and nerve contents of each label were measured 30 or 60 sec later. Iodoantipyrine values were used to calculate blood flow to these portions of the nervous system. The ratio of Rb86 to iodoantipyrine uptake was used as an index of the efficacy of the hematoneural barrier. The barrier is most complete in the brain, less complete in the spinal cord, and absent in peripheral nerve. Blood flow values per gram are: brain .41 ml/g min; cord .28 ml/g min, and nerve .11 ml/g min. It is suggested that the blood-brain barrier is an anatomical entity rather than a functional one.