Leo A. Sapirstein

Fractionation of the Cardiac Output of Rats with Isotopic Potassium

A single injection of K42 given intravenously is initially distributed among the organs in proportion to the blood flow through them. By determining the organ content of K42 after such an injection the cardiac output may be fractionated. The conditions and limitations of the method are discussed and values are given for the fractional distribution of the cardiac output in the rat.

Effect of Hemorrhage on the Cardiac Output and Distribution in the Rat

The effects of moderate and severe hemorrhage on the cardiac output and its distribution have been studied in the rat. In moderate hemorrhage, cerebral and adrenal blood flow are well maintained through localized vasodilatation while most other organs show increased vascular resistance and diminished blood flow. After severe hemorrhage, despite further changes in territorial resistances, the blood flow is not maintained in any area of the body.

Alcohol and Regional Blood Flow in Brains of Rats

Summary Alcohol, in large amounts, increases the blood flow to brains of man and other animals. To what extent blood flow to specific regions of the brain varies with smaller, nonanesthetizing doses has been the subject of the present study. A new radioisotopic method was employed which permitted the simultaneous measurement of blood flow to each of ten regions of the brain in unrestrained, unanesthetized animals as small as rats. Three doses of alcohol were used: a low dose causing no behavioral change, an intermediate dose causing lack of coordination but no loss of consciousness, and a high toxic dose producing anesthesia. The blood levels of alcohol causing various signs of intoxication were the same in rats and man. At the low dose, no changes were seen in brain blood flow. At the intoxicating dose slight, but insignificant, increases were seen in the basal ganglia, frontal cortex, and olfactory bulb, while hippocampal blood flow decreased. At the anesthetic dose, blood flow increased to the olfactory bulb and the brain stem and actually decreased slightly to the parietal cortex. Support of the depressed ventilation rate observed at this dose of ethanol restored the pCO2 and pO2 values to control levels but did not reverse the observed acidosis; cardiac output fell, signaling increased peripheral resistance. Under these circumstances, the flow of blood to all brain regions fell, most notably to the hippocampus, cerebellum, and parietal cortex. The effects of ethanol and pentobarbital are compared. We are indebted to Dr. D. Knowlton for the analyses of blood levels of ethanol. This work was supported in part by a grant from The Licensed Beverage Industries and by Public Health Service Grant NB05526.

Theoretic Limitations of the Nitrous Oxide Method for the Determination of Regional Blood Flow

The nitrous oxide method for regional blood flow determination is based on the assumption that concentration equilibrium for nitrous oxide between the organ and its venous blood is reached. This assumption is examined, and it is shown mathematically that faulty equilibrium is not revealed by presently available criteria. It is shown that quantitatively and qualitatively erroneous results may be obtained by the use of this method for the estimation of regional blood flow.

Catheter Induced Error in Hepatic Venous Sampling

That the composition of hepatic venous blood sampled by catheter is not representative of the mixed hepatic venous blood has been shown by demonstrating that the concentrations of mesenterically infused para-aminohippuric acid and systemically infused Rose Bengal are exceedingly variable in blood sampled by a catheter placed at various positions within the hepatic venous system. These results suggest that a large and previously unsuspected error may confound the estimation of hepatic blood flow by dye infusion technics employing catheterization of the hepatic veins.

Effect of Ether Anesthesia on the Cardiac Output, Blood Pressure, and Distribution of Blood Flow in the Albino Rat

Rats anesthetized with ethyl ether were compared with rats anesthetized with sodium pentobarbital from the standpoint of cardiac output, peripheral resistance and regional blood flow. Cardiac output was measured by the indicator-dilution technic; regional blood flow was determined by the indicator-fractionation technic employing Rb86 or I131-antipyrine. The cardiac output is one and a half times as great in ether anesthesia as in pentobarbital anesthesia; the peripheral resistance is about two-thirds as great with ether. Compared to pentobarbital, ether increases myocardial, cerebral, and carcass blood flow, while decreasing renal, splanchnic and cutaneous blood flow. The pronounced difference in the cardiovascular effects of the two agents indicates the need for caution in the interpretation of experiments in which cardiovascular measurements are made under anesthesia.

Distribution of Myocardial Blood Flow in the Rat

RubidiumS6 distribution was used to estimate the distribution of myocardial blood flow in albino rats. The results indicate that the perfusion rates of the left ventricle, apex and interventricular septum are all substantially identical, averaging 2.6 to 2.9 ml./Gm. of tissue/min. The value for the right ventricle is 3.2 ml./Gm./min. The implications of these findings for the measurement of coronary blood flow by the nitrous oxide method are discussed.

Fractional Distribution of Right Ventricular Output in the Lungs of Dogs

Microspheres, approximately 50 μ in diameter and labeled with scandium46, were injected into the jugular vein of seven anesthetized dogs. Each lobe of lung contained nearly equal counts per minute per gram of tissue. This suggests that the indicator was completely mixed with the blood by the time it arrived in the pulmonary artery, and that the perfusion rate of blood per gram of lung is nearly identical for all lobes.

Distribution Volumes of T-1824 and Chromium51 Labelled Red Cells Immediately Following Intravenous Injection

The difference in distribution volumes of T-1824 and Cr51 labelled red cells is fully realized within 30 sec. after their simultaneous intravenous injection in the dog. This indicates the existence of a rapidly circulating extravascular protein pool.

A rapid blood sample collector for use in the determination of cardiac output

Abstract A plastic disk with appropriately spaced holes in the circumference is described for convenient collection of arterial blood samples at one- or two-second intervals for the determination of cardiac output by the dye-dilution method. A complete determination and cleaning of the apparatus may be easily completed in less than an hour.