bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical activity of the longitudinal muscle of dog small intestine studied in vivo using microelectrodes
Authors: Daniel E. E. , Honour A. J. , Bogoch A.
Published: December 2017

The electrical activity of longitudinal muscle cells of the small intestine of the dog have been recorded in vivo using microelectrodes. This activity is characterized by periodic slow depolarizations of from 3 to 15 mv starting from potentials of 35–50 mv. The frequency of these slow depolarizations is less in the ileum than in the jejunum and is diminished by reduction in body temperature. Asphyxia diminishes both frequency and amplitude of these slow depolarizations without affecting the resting potentials. Action potential spikes arise from the larger slow depolarizations. The records obtained in this study are compared with previously recorded monopolar extracellular records. It is concluded that the slow waves recorded using extracellular electrodes arise from slow depolarizations of intestinal muscle cells. It is proposed that these slow depolarizations are a coordinating mechanism for motility of the longitudinal muscle of the dog intestine. The mechanism of synchronization of the slow waves themselves remains to be elucidated.
Effect of handling on the thyroidectomized rat
Authors: Elrick Harold , Borda-Bossana D. , Diamant E. , Bernstein L. , Whitehouse J. M.
Published: December 2017

Experiments on the effects of handling of the thyroidectomized rat were performed. Handling resulted in significantly better maze learning ability, but had no effect on weight gain, food consumption or resistance to thiourea toxicity. The findings are compared with those previously obtained in the normal, hypophysectomized and adrenalectomized rat.
Proteolytic and polymerase activity of thrombin
Authors: Landaburu Ricardo H. , Seegers Walter H.
Published: December 2017

In addition to splitting peptides from fibrinogen, thrombin is necessary for the polymerization of fibrin monomer. Thrombin also uses fibrin as a substrate and eventually the clot may lyse. On the basis of these views, previous equations used to outline the events when thrombin and fibrinogen are mixed can be revised as follows: Proteolysis: F + T ⇆ f + P + T (1) Polymerization: Nf + T ⇆ NfT (2) (fibrin clot) Proteolysis: NfT → Inf + T + P2 (3) F is fibrinogen, T is thrombin, f is fibrin monomer, P is peptides and carbohydrates, N is any number, Inf is inactive fibrin monomer, and P2 is peptides or any reaction products. As the thrombin concentration increases the polymerization time becomes shorter. TAMe retards the polymerization time. For a given thrombin concentration the clotting time of fibrinogen may be inversely proportional to the concentration of fibrinogen. Most of the clotting time is accounted for as polymerization time, but the amount of thrombin required for the latter is relatively small. In 3 m urea solution thrombin may irreversibly lose its activity. When protected by a substrate such as TAMe, fibrinogen or fibrin, thrombin is active in urea solution. The activity then depends upon TAMe concentration under conditions when the enzyme behaves as if saturated with the substrate. To have this activity in urea solution the substrate must be in the urea before the thrombin is added. Esterase thrombin also uses fibrin as a substrate; it is, however, not a polymerase. It does not use fibrinogen as a substrate.
Role of plasma lipids in transport of fatty acids for butterfat formation
Authors: Riis P. M. , Luick Jack R. , Kleiber Max
Published: December 2017

Cow plasma containing P32- and C14-labeled lipids and proteins was infused into a lactating cow. The specific activity of the lipids and volatile acids of the plasma and of the expired CO2 and milk constituents was determined. The turnover rate of phospholipid P and of plasma lipid volatile acids was 0.1 hours–1, this means a half-time of 7 hours. Little radioactivity was found in the expired CO2 and none was found in plasma volatile acids. These findings and the distribution of C14 in milk constituents indicate that plasma proteins do not contribute carbon to butterfat and that the catabolism of plasma lipids and proteins does not lead to a significant formation of nonlipid butterfat precursors. These observations permit a further calculation which indicates that 50% of the butterfat C originates from plasma lipid C.
Renal metabolism of salicylate and salicylurate
Authors: Despopoulos Agamemnon
Published: December 2017

The renal metabolism of salicylate, salicylurate and p-aminohippurate (PAH) is examined to establish whether all three compounds share similar renal excretory mechanisms. The experimental data are collated with recorded observations of other investigators. In renal cortical slices, salicylurate is actively accumulated but salicylate is not. Slice to medium concentration ratios for salicylurate (as for PAH) are increased by acetate, and decreased by probenecid and by anoxia; under similar conditions, concentration ratios for salicylate remain unchanged. Both salicylate and salicylurate inhibit renal transport of PAH, but the effect of salicylate is associated with an enhanced tissue respiratory rate, thereby differing from salicylurate. These findings suggest that the renal metabolism both of salicylurate and of PAH are similar if not identical and both differ from that of salicylate.
Blood and cerebrospinal fluid glucose in the fasting state
Authors: Cooper Richard G. , Archdeacon James W.
Published: December 2017

A glucose oxidase method for determining glucose was used in analyzing the blood and cerebrospinal fluid in dogs. The animals were fasted from 66 to 84 hours and venous blood and cerebrospinal fluid samples were withdrawn simultaneously during this time. In 13 determinations the glucose concentration in the fluid from the cisterna magna was equal to or slightly higher than the glucose concentration in blood from the cephalic vein. In seven instances the venous glucose concentration was higher. There was a tendency, not always uniform, for the glucose level to drop slightly in both compartments as the days of fasting progressed. Greater fluctuation was observed in the venous glucose level than in the cerebrospinal fluid glucose level.
Transport of potassium by the gastric mucosa of the frog
Authors: Harris John B. , Edelman Isidore S.
Published: December 2017

The transport of potassium across the isolated frog gastric mucosa was studied by the chamber method. The net flux of potassium from the nutrient to the secretory phase ( JnsK) did not follow the predictions of simple passive diffusion when the mucosa was incubated with equivalent concentrations of K+ in the secretory and nutrient phases. Furthermore, a net gain in secretory potassium occurs against the electrochemical potential gradient if the mucosa is first incubated with nutrient solutions containing 4 mEq/1. of K+. Neither the loss of K+ from mucosal cells nor solvent drag appears to account for the positive values of JnsK under these circumstances. These data indicate, therefore, that there is a small but significant component of active potassium transport in this preparation.
Potassium and the transmucosal resistance of the frog gastric mucosa
Authors: Harris John B. , Edelman Isidore S.
Published: December 2017

The effects of modifications in the potassium concentration of nutrient solutions (K n) on the transmucosal potential difference (p.d.), initial resistance ( Ri), final resistance ( Rf) and the calculated initial current flow ( Ii) and final current flow ( If) were studied in vitro with application of external currents by direct current analysis. Stepwise increase of K n from 1 to 9 mEq/l. resulted in a 53% fall in p.d., a 14% fall in Ri and a 46% fall in Ii. The ratio of Ri: Rf remained constant at all K n levels, i.e. If fell to the same extent as Ii. When K n was raised to 40 mEq/l., the orientation of the p.d. reversed, indicating a net charge transfer of cation in excess of anion into the secretory phase. The ratio of the current flow at K n > 1.0 mEq/l. to the current flow at K n = 1.0 mEq/l. was found to vary linearly with K n. These data suggest that elevation of K n depresses active chloride transport while sustaining or enhancing the rate of hydrogen ion production. Alternative explanations of these results are discussed in the text.
Transfer of zinc65 across the placenta and fetal membranes of the rabbit
Authors: Terry Carolyn W. , Terry Boyd E. , Davies Jack
Published: December 2017

The distribution of radioactivity in the fetus and placental structures (fetal placenta, decidua, yolk sac) has been studied at different stages of gestation following the intravenous injection of Zn65 into the mother. The uptake of radiozinc by the products of conception increased with advancing gestation but never exceeded 8% of the total dose given. The recovery rose sharply between the 20th and 22nd day, suggesting the maturation of a fetal acceptor organ or an increased efficiency of the placental transport mechanism. Evidence is presented that the fetal liver is mainly responsible for the increased fetal recovery in the later stages of pregnancy. In addition, the placental recovery of radioactivity following the removal of the fetuses is equal to that obtained from the combined fetuses and placentae in the control side of the uterus; this suggests that the removal of radiozinc from the maternal blood is not dependent on a fetal acceptor. The transfer of radiozinc from the maternal blood is almost entirely via the fetal placenta. The yolk sac plays an insignificant part in both the storage and transport of the metal. Retrograde transfer from the fetus to the mother has also been demonstrated.
Serial pressure-volume studies in the excised canine heart
Authors: Griggs Douglas M. , Holt Peter R. , Case Robert B.
Published: December 2017

Serial left ventricular pressure-volume curves were obtained on excised canine hearts maintained at different constant temperatures. The technique employed permitted detection of slight changes in distensibility of the ventricular wall and in shortening of muscle fibers. The results demonstrated that the ventricular distensibility and fiber length at 36°C were unaffected until approximately 80 minutes after excision, beyond which time they decreased rapidly at a constant rate. Hypothermia prolonged the onset and rate of these changes and, at 5°C, changes did not occur until after 5 hours. Sodium fluoride, injected into the left coronary artery in order to block glycolysis, induced early and rapid changes in distensibility and fiber length.
Role of the pancreas in reduction of fecal fat and cholesterol by dietary protein
Authors: Fragola L. , Magee D. F.
Published: December 2017

Rats with separation of the pancreatic ducts and sham-operated controls were fed 8% and 30% casein diet. The fecal fats were lowered by the high-protein diet in each case. The magnitude of the decrease was not different in the two groups. The experiment was repeated with the addition of 2% cholesterol to the two diets. Both groups of animals while on the high-protein diet had less fecal cholesterol than when on the low-protein regimen.
Initiation of blanch-blush cycles in the mouse uterus by cholinergic drugs
Authors: Allgood Joel W. , Worthington W. Curtis
Published: December 2017

Epinephrine, Mecholyl and acetylcholine were tested for their effects on the ‘blanch-blush’ phenomenon of the uterus in 29 mice in three groups (ovariectomized, ovariectomized and estrogen-treated, and intact animals in estrus and diestrus). Spontaneous blanch-blush cycles occurred in each group. They were longer and more intense in the ovariectomized animals. Local application of acetylcholine and Mecholyl were followed by blanch-blush cycles similar to spontaneous cycles. Duration and intensity of these cycles varied directly with the concentration of the drugs. Atropine locally applied effectively blocked or interrupted the cycles associated with acetylcholine and Mecholyl application. Local application of epinephrine was followed by constriction of the vessels in the uterus. The evidence for the probability that an acetylcholine-like substance plays some role in the regulation of the blanch-blush phenomenon is examined and discussed.
Prolonged and patterned direct extracellular stimulation of single neurons
Authors: Strumwasser Felix , Rosenthal Suzanne
Published: December 2017

Current parameters for direct extracellular excitation and inhibition of single neuron activity in the frog brain (by application of current through the recording micropipette) are described. Rheobase for normally inactive cells is between 1 and 3 x 10–9 A; threshold for modulation of activity in spontaneous cells (25% effects) is about 2.5– 3.5 times lower than for initiation of activity in inactive cells. Rebound from inhibition, accumulation of post-inhibitory rebound, escape from inhibition, postexcitatory rebound depression and off-responses and after-discharges to direct stimulation are described at the unit level. The comparative aspects of current sensitivity of neurons is discussed and with the exception of the specialized electrical receptor in some fish, it is concluded that neurons so far investigated have no more sensitivity (slope, impulses/sec/10–9 A) to current than a nonadapting 20–30 µ diameter invertebrate unmyelinated nerve. The responses of cells after sustained depolarizations and the behavior of cells to patterned intermittent depolarizations are described; long after effects are revealed. Evidence is presented that some of the effects appear to be due to positive and negative feedback presumably from a small population of interconnected neurons whose activity can be modified by the one cell being excited. It is suggested that the classical excitabilities so far studied in single neurons are perhaps only rarely the limiting factors in natural patterned neuronal activity.
Brain stem augmentation of cardiovascular activity
Authors: Glasser Richard L.
Published: December 2017

Midpontile ischemic decerebration in vagotomized mesencephalic cats produced marked tachycardia and hypertension. Subsequent transection of the brain stem at or above the midpontile level did not affect the cardiovascular hyperactivity. Transection at the pontomedullary junction abolished the brain stem augmentation of heart rate and blood pressure. The results suggest the existence of a cardiovascular augmenter area in the caudal half of the pons and a cardiovascular depressor area in a more rostral portion of the brain stem.
Patterns of response of the paravertebral musculature to visceral stimuli
Authors: Eble John Nelson
Published: December 2017

Stimulation of abdominal viscera provokes reflex contractions of the paravertebral muscles. The reflex contractions change in intensity and in number of segments involved with variations in degree of stimulus. With minimal stimuli the response is limited to two or three segments. With increasing intensity of stimuli the response spreads to include adjacent segments and can extend to the contralateral side. Such visceromotor reflexes have been shown for the renal pelvis, ureter, small intestine and fallopian tube. When an unpaired organ such as the intestine is stimulated, the response is bilateral even to minimal stimuli. To a prolonged stimulus there is a build-up to a peak activity followed by a decrease which is then maintained for variable periods from seconds to hours. Such prolonged activity also frequently follows very brief stimuli. The influences of drugs and other stimuli on these visceromotor reflexes are demonstrated.
Function of the bovine omasum in ingesta transfer
Authors: Stevens C. E. , Sellers A. F. , Spurrell F. A.
Published: December 2017

Motor events in the omasum were studied by recording reticulo-omasal pressure changes and attempting to correlate these with ingesta flow. Fluid-filled, open-tipped catheters and strain gauges were used. Ingesta flow was studied by fluoroscopic examination, palpation, a funnel-reservoir system and by use of the Pitot tube principle. Results indicated that the omasal canal undergoes contraction with each primary and secondary contraction of the rumen. It is proposed that omasal canal contractions force more fluid components of the ingesta from the canal between the leaves of the omasal body. Canal contractions were often followed by contraction of the omasal body which forced accumulated fluid ingesta into the abomasum. The greatest flow of ingesta from the reticulum appeared to occur directly following the canal contractions. Backflow of large volumes of ingesta from omasum to reticulum was occasionally noted and seemed to occur when the omasal body contracted during closure of the omaso-abomasal orifice. Implications of this are discussed.
Nonsyncytial nature of cardiac muscle: membrane resistance of single cells
Authors: Sperelakis Nick , Hoshiko T. , Berne Robert M.
Published: December 2017

Previous work suggested that the myocardium is not a functional syncytium. In the present study of isolated frog ventricle, constant-current pulses were used to estimate the d.c. resistance between two microelectrodes when: a) both were extracellular, b) one was intracellular, and c) both were intracellular. A resistance of 12.4 ± 0.5 megohms was obtained for single cells. This large resistance indicates that the cells are functionally small units. The resistance between two cells was about twice that of one cell and was independent of the distance between the cells. Hence there are no low resistance pathways between cells. The results support the hypothesis that conduction in the heart does not involve a functional syncytium; rather junctional transmission may occur from cell to cell. Myocardial cells which had been previously punctured generally showed a much lower resistance, even though the resting and action potentials were normal.
Effects of calcium deficiency on cell membrane potentials of isolated frog hearts
Authors: Ware F. , Bennett A. L. , McIntyre A. R.
Published: December 2017

Membrane potentials were recorded in isolated frog hearts. Observations were made on the effects of calcium deficiency upon resting potential, action potential, overshoot, maximum depolarization rate and action potential contour. Calcium deficiency caused a significant fall in all observed potentials. Maximum depolarization rate was increased. Early repolarization rate was markedly decreased. Chelation of calcium caused changes indistinguishable from those caused by omission of the ion from the perfusate. These results are discussed in relation to current concepts.
Performance characteristics of the right heart bypass preparation
Authors: Grodins Fred S. , Stuart William H. , Veenstra Rodney L.
Published: December 2017

In eight dogs under morphine-barbital anesthesia, the right ventricle was replaced by a sigmamotor pump in order to study steady-state responses of circuit pressures to arbitrary variations in ‘right heart’ output. In the systemic circuit, it was found that arterial pressure (PAS, mm Hg) was a positive and venous pressure (PVS, mm Hg) a negative function of pump output (Q, cc/min). In the pulmonary circuit, both arterial (PAP) and left atrial (PLA) pressures were positive functions of pump output. Despite considerable variations in detail between animals, individual animal pressure-flow curves could all be represented to a reasonable degree of approximation by linear functions within the range of the data. Average regression equations for the eight animals were: PAS = 18.3 + 0.0639Q, PVS = 20.2 – 0.0124Q, (PAS – PVS) = 0.0756Q – 1.59 PAP = 11.2 + 0.0151Q, PLA = 7.0 + 0.00208Q, and (PAP – PLA) - 3.9 + 0.0154Q. These results were interpreted in terms of a quantitative theory of mechanical self-regulation in the cardiovascular system.
Effect of 1,2,4-triazole ethylamine on gastric secretion
Authors: Ivy A. C. , Liepins K. W.
Published: December 2017

3-(beta-aminoethylamine)-1,2,4-triazole, the triazole analogue of histamine, was found to be a potent excitant of gastric secretion, 0.42 mg of the triazole base being equivalent to 0.3 mg histamine in the dog. The action was slightly more prolonged than that of histamine. The evidence in this study along with earlier evidence strongly indicates that aminoguanidine (AG) acts additively with histamine, since AG inhibits the destruction of histamine. It was found that AG also augments the action of the triazole on gastric secretion, the mechanism of which is now uncertain.
Response of three strains of albino rats to xylose and galactose
Authors: Heggeness F. W.
Published: December 2017

Development time of cataracts induced by feeding a 60% galactose diet was 32 days for Carworth Farm Nclson (CN) strain rats, 20 days for Rochester colony-ex Wistar (RW) strain and 14 days for the Holtzman (H) strain animals. The magnitude of galactose calcariuria associated with galactose feeding was not significantly different in these three strains. A greater galactose-induced depression in bile volume flow occurred in animals of the H and RW strains than in the CN strain rats. No ophthalmologic changes developed in CN strain animals during the feeding of a 30% xylose diet. Cataractous changes accompanied by the characteristic decrease in lens potassium content occurred in RW and H strain rats fed xylose. Ophthalmologic changes were more marked in the H strain. These findings provide further evidence that a common mechanism is involved in the cataractous changes associated with xylose and galactose. Also, the findings suggest that the galactose-induced depression in bile volume flow but not the calcariuria show similar strain variations.
Role of the sympathetic nervous system in CCl4 hepatotoxicity
Authors: Calvert Deane N. , Brody Theodore M.
Published: December 2017

An hypothesis is proposed which states that the characteristic hepatic changes seen after the administration of carbon tetrachloride are the result of stimulation of central sympathetic areas which produce a massive discharge of the peripheral sympathetic nervous system. Stimulation of the sympathetic supply to the blood vessels of the liver results in restriction of blood flow in the liver, leading to anoxia and the characteristic necrosis around the central vein of the hepatic lobule. Similarly the discharge causes the release of unesterified fatty acids from the peripheral fat depots and the consequent deposition of lipid in the liver. This hypothesis is based upon experimental evidence using the following physiologic and pharmacologic maneuvers: adrenergic blocking agents, pretreatment with reserpine, adrenalectomy and section of the spinal cord—all are effective to a greater or lesser extent in preventing the changes characteristically seen in oxidative phosphorylation of the liver mitochondria, activation of a Mg-dependent ATPase and deposition of lipid in the liver. Transection of the spinal cord is the most effective treatment and prevents entirely the characteristic changes seen in the above-mentioned functions.
Functional changes in liver mitochondria following in situ anoxia
Authors: Moore Kenneth E. , Brody Theodore M.
Published: December 2017

Liver anoxia was produced in rats by ligating the anterior mesenteric and celiac arteries and the portal vein for a 2-hour period. Mitochondria prepared from the livers of these animals were compared with normal or sham-operated rats. Mitochondrial protein from treated liver was lower than normal by almost 50%. In the anoxic mitochondria the potassium ion concentration decreased, the Mg ATPase was stimulated and the dinitrophenol ATPase was inhibited. There was an impairment of the DPN-linked dehydrogenase activity while succinate oxidation was less affected. Oxidative phosphorylation was uncoupled with pyruvate, α-ketoglutarate and ß-hydroxybutarate but unaffected with glutamate and succinate. A method for the measurement of mitochondrial swelling in vivo is presented and indicates that mitochondria from liver of treated animals are swollen. The changes in mitochondrial function following in situ anoxia are compared with those changes seen following carbon tetrachloride administration.
Release of catechol amines from the adrenal medulla by CCl4
Authors: Brody Theodore M. , Calvert Deane N.
Published: December 2017

The single oral administration of an hepatotoxic dose of carbon tetrachloride (CCl4) causes a decrease in the amount of apparent epinephrine and norepinephrine in the adrenal medulla after 20 hours. There is also a parallel increase in the wet weight of the adrenal gland. The ability of CCl4 to induce catechol amine depletion has been demonstrated in both the rat and the rabbit. Adrenals of animals whose spinal cords have been transected prior to CCl4 administration do not exhibit this decrease in catechol amine content. These results will be discussed in the light of an hypothesis that the toxic action of CCl4 is an indirect one and may be mediated via a release of catechol amines.
Experimental obesity and osteoarthritis
Authors: Sokoloff Leon , Mickelsen Olaf , Silverstein Emanuel , Jay George E. , Yamamoto Richard S.
Published: December 2017

Experimental obesity was produced in DBA/2JN, STR/N and C57L/HeN mice as well as in Osborne-Mendel rats by several dietary regimens. One of these, containing 60% vegetable fat, increased the amount of degenerative joint disease in the rats and in two strains of mice. No increase of osteoarthritis occurred as a result of a 37.4% fat content in the diet, or from obesity produced by Ingle's diet, which has a relatively low-fat content. The mechanism by which the high-fat diet increased the joint disease is unknown, because neither obesity nor a high-fat diet alone had a deleterious effect on the articulations of the mice. Obese hybrid mice derived from a spontaneously obese and arthritis-prone strain (STR/1N) were resistant to articular degeneration. Dietary restriction of weight gain in the STR/1N mice failed to decrease the osteoarthritis in them.
Rate of loss of radioiron from mouse and man
Authors: Bonnet John D. , Orvis Alan L. , Hagedorn Albert B. , Owen Charles A.
Published: December 2017

Forty-two male and female mice, 8 weeks old, were given radioiron (Fe59) in doses of 0.006–0.1 µc, containing 0.013–0.17 µg of iron, by intraperitoneal or intravenous routes. Assays of the radioactivity of the whole body revealed an initial rapid loss of Fe59 (15–20%) lasting about 6 days. Thereafter the Fe59 left the mice at a steady rate of 0.39%/day (half-life 180 days). One 34-year-old normal man was given 10.6 µc of Fe59, containing 8.2 µg of iron, intravenously. Based on counts from the entire body, the biologic rate of loss of the Fe59 was about 0.14%/day (half-life 500 days), and there was little or no initial loss such as occurred in the mouse. The Fe59 in the circulating erythrocytes was essentially unchanged for the first 3 months. It then fell to a new level of about 90% of the previous one; the mid-point of the fall was about 120 days after the administration of the radioiron. The difference in the rates of loss of radioiron from mice and man seems to be related primarily to the life span of the circulating red cells.
Renal excretion of radiofluoride in the dog
Authors: Carlson Curtis H. , Armstrong W. D. , Singer Leon , Hinshaw Lerner B.
Published: December 2017

Renal clearances of continuously infused radiofluoride were measured in 10 dogs in which a large part of the skeleton had been excluded from the system in order to produce a more constant plasma radiofluoride concentration. The results were evaluated to describe the factors of glomerular filtration and tubular reabsorption of fluoride under several conditions. The animals that received carrier-free radiofluoride infusions excreted urine with a mean radiofluoride concentration 3.4–14.5 times that of the plasma. The urine-to-plasma concentration ratios obtained with animals given a load of stable fluoride was 13.5–29.6. An increased urine volume resulted in a decreased tubular reabsorption of fluoride and the clearance was increased. Chlorothiazide increased radiofluoride excretion but decreased the urine concentration. The radiofluoride clearances were always less than the creatinine clearances but were 7.8–179 times the chloride clearances. The effect of chlorothiazide was to decrease the ratio of fluoride to chloride clearance by increasing chloride clearance more than fluoride clearance.
Active transport of potassium by heart mitochondria
Authors: Ulrich Frank
Published: December 2017

Rabbit heart mitochondria contained potassium which could not be removed with four washings of isotonic sucrose or sodium chloride at 0–4°C. Aging, increasing concentrations of potassium, and a number of metabolic poisons either partially or completely inhibited the active transport of potassium into heart mitochondria when these particles were incubated for 15 minutes in air at 37.4° in a medium to which alpha-ketoglutarate and AMP or ATP had been added. Compounds uncoupling oxidative phosphorylation—such as arsenite, 2,4-dinitrophenol, l-thyroxine, calcium chloride, dicumarol, pentachlorophenol and methylene blue—inhibited potassium transport but usually only at relatively high concentrations (10–3 m). With the exception of p-chloromercuribenzoate, neither aging nor metabolic inhibitors prevented the extrusion of water by the mitochondria in the presence of alpha-ketoglutarate and AMP or ATP. Although addition of either ATP or substrate alone to the mitochondrial suspension resulted in a significant increase in the potassium gradient, the latter was much greater when both substrate and ATP (or ADP or AMP) were added together. ADP or AMP alone caused a very slight but probably not significant increase in the potassium gradient and creatine phosphate had no effect.
Estimation of hepatic blood flow using a single injection dye clearance method
Authors: Banaszak Edward F. , Stekiel William J. , Grace Robert A. , Smith James J.
Published: December 2017

In dogs anesthetized with morphinesodium barbital, hepatic blood flow was estimated from the concentration-time slopes of peripheral arterial and hepatic venous blood following a single injection of either indocyanine or BSP. The injection of indocyanine in doses ranging from 5 to 50 mg produced 20-minute decay slopes which were logarithmic. The mean estimated hepatic plasma flow in 25 dogs using indocyanine was 23 ± 1.3 ml/kg/min. and the mean estimated hepatic blood flow was 43 ± 2.2 ml/kg/min. These mean blood flow values were about 12% higher than the hepatic blood flows estimated with Bradley's constant infusion (BSP) method but there was quite close agreement in hepatic plasma flow values with the two methods. The mean indocyanine space in 25 dogs was 49 ± 1.4 ml/kg. Indocyanine appears to be preferable to BSP for use with the single injection method. From a theoretical as well as practical standpoint, the single injection method appears to have potential usefulness for the estimation of hepatic blood flow.
Effects of various ganglionic blocking agents on blood pressure and on activity of pressor agents
Authors: Haas Erwin , Goldblatt Harry
Published: December 2017

Five structurally dissimilar ganglioplegic drugs used in the diagnosis and treatment of human hypertension were investigated in normotensive, trained dogs under conditions of profound, uniform, ganglionic blockade. Slow, continuous intravenous infusion did not lower the blood pressure of the conscious dog, and even induced a slight elevation. In a model experiment with tetraethylammonium chloride, the effect on the blood pressure depended on the rate of administration of the drug and on the state of consciousness of the animal. Rapid intravenous injection of a massive dose into an anesthetized dog, induced a profound fall of blood pressure. The pressor action of sympathomimetic amines, whether administered in a single dose or by continuous slow infusion, was greatly enhanced by the administration of ganglionic blocking agents, but the activity of other pressor agents, such as angiotensin and renin, was not enhanced under identical conditions. It is concluded that the potentiation of pressor agents cannot be ascribed to the blockade of compensatory, autonomic reflexes or to the considerable increase in heart rate which was observed in conscious dogs in all the experiments with ganglionic blocking agents.
Comparative effects of prenatal gamma radiation and x-irradiation on the reproductive system of the rat
Authors: Ershoff Benjamin H. , Brat Ved
Published: December 2017

Experiments were undertaken to determine the comparative effects of prenatal x-irradiation and gamma radiation from a cesium-137 source on the development and morphology of the reproductive system of the young rat. Findings indicate that a sex difference in response occurred. The male offspring of rats exposed to either 300 r x-irradiation (administered as a single dose at the rate of 17.92 r/min.) on the 18th day of pregnancy or to 300 r gamma radiation administered continuously from the 13th to 20th day of pregnancy (at a dose rate slightly less than .03 r/min.) exhibited a significant degree of gonadal injury. In female offspring, the ovaries were normal in size and appearance in the case of rats whose mothers were administered x-irradiation, but were significantly reduced in size and contained neither follicles nor corpora lutea when the mother rats received gamma radiation.
Changes in bone sodium during acute acidosis in the rat
Authors: Bergstrom W. H. , Ruva Frank D.
Published: December 2017

Acute acidosis was induced in male albino rats by intraperitoneal dialysis against ammonium chloride. The concentration of sodium in the inorganic phase of bone was measured at short intervals following the procedure to determine the rate and extent of change. Bone sodium loss was immediate in onset, linear in rate and complete in 4 hours. The amount released was 28% of the original total. The equations Na = 157 – 10 T (when Na = mEq/kg fresh bone and T = hours after dialysis) and log Na = 2.1932 – 0.0318 T expressed the observed changes equally well.
Similarity of cardiovascular responses to exercise and to diencephalic stimulation
Authors: Smith Orville A. , Rushmer Robert F. , Lasher Earl P.
Published: December 2017

Devices to measure left ventricular pressure, diameter and heart rate in animals with closed chests were placed on the hearts of dogs. After recovery from this operation the dogs were trained to exercise on a treadmill and the cardiovascular responses to this exercise were recorded. Stimulating electrodes were then stereotaxically placed in the diencephalon. In some dogs the electrodes were chronically implanted, and the stimulation was carried out after recovery from this second operation. In other animals stimulation was carried out immediately while they were under chloralose anesthesia. Stimulation of the H1 and H2 fields of Forel and the periventricular gray of the third ventricle resulted in cardiovascular responses similar to those which result from exercise.
Red blood cell volume and distribution before and after bleed-out in the rat
Authors: Dellenback Robert J. , Muelheims Gerhard H.
Published: December 2017

The distribution of red blood cells in nine normal Nembutalized rats (323.2–415.0 gm body weight) was determined by the Cr51-labeled red blood cell technique. Microliters of red blood cells per total and per gram of tissue are reported for the testes, brain, intestine, kidney, heart-lung, spleen, liver, bone, muscle and skin. Values are also listed for the same organs and tissues determined after rapid bleed-out as found by Muelheims, Dellenback and Rawson. A comparison of these values shows that the liver, heart-lung and muscle contribute approximately 80% of all red blood cells removed in the hemorrhage. The skin, bone, kidney and intestine contribute as a group the remaining 20% with a negligible contribution from the testes and brain and no contribution from the spleen.
Acute magnesium depletion and excess induced by hemodialysis
Authors: Grantham Jared J. , Tu W. H. , Schloerb Paul R.
Published: December 2017

The present study was undertaken to investigate in dogs the effects of acute magnesium depletion and excess induced by hemodialysis. Bath fluid for the hemodialyzer was normal in extracellular electrolyte concentrations and pH, except for magnesium which was omitted or added for the respective depletion and excess studies. Plasma depletion 58% of the original magnesium concentration was observed in a steady state following 90 minutes of dialysis. The rate of magnesium extraction during this steady state was 0.7 mEq/hr. Following 150 minutes of dialysis to induce depletion, blood pressure, electrocardiogram and observed physical signs demonstrated no remarkable aberrations when compared with the control animals, other than giant hives which developed in two of the depletion animals. With loading studies, plasma magnesium concentrations which were increased to 15 mEq/l. in nephrectomized dogs, were accompanied by anesthesia, slowing of pulse rate and minimal lengthening of the P-R and Q-T intervals. It is concluded that marked alterations of the extracellular magnesium ion concentration are accompanied by slower compensatory changes in nonextracellular magnesium.
Effects of potassium on frog skeletal muscle in a chloride-deficient medium
Authors: Falk Gertrude , Landa Jorge F.
Published: December 2017

Muscle fibers give prolonged action potentials with a characteristic plateau in a medium in which chloride has been replaced by anions which do not carry charge across the membrane. Repolarization is aperiodic or oscillatory with negative damping. Duration of the plateau and growth of oscillations are potassium sensitive and independent of changes in resting potential. In the absence of external K, spontaneous spikes are fired off until the membrane potential becomes set at the plateau level or oscillates in the region thereof. Fibers remain depolarized indefinitely until K is added. A fiber may have two modes of oscillation, one associated-with deviations from the resting state, the other with a depolarized steady state. Both forms of oscillations belong to excitable systems but their voltage dependence differs. Lithium can substitute for sodium in the prolonged response.
Prompt effects of high-level irradiation on animal metabolism
Authors: Ellis James P. , Clark Robert T. , Rambach Walter A. , Pickering John E.
Published: December 2017

Blood acid-base related components and free amino acids in plasma, spinal fluid, and five tissues were measured in rhesus monkeys exposed to whole-body irradiation doses (500– 30,000 r). Samples collected 2 hours later showed increased acidity in blood. This change was paralleled by a rise in blood lactic acid. No consistent change was found in blood pyruvate. A correlation of these findings with reductions in the arterial CO2 tension and plasma CO2 content indicated that the metabolic acidosis was greater than the respiratory alkalosis resulting from increased pulmonary ventilation. Two-dimensional chromatograms indicated that plasma glucose was reduced and plasma uric acid was increased. The altered levels were related to the postirradiation interval and the total dose. The free amino acid content of plasma was increased in proportion to the dose. Of the seven amino acids detected in spinal fluid, an elevated glutamine level was the only consistent change.
Changes in sensitivity of uteri of ovariectomized rats to estrogen in relation to age
Authors: Liu Frank T.Y.
Published: December 2017

Groups of female rats, ovariectomized at 21 days of age, were injected with 0.5 µg estradiol-17ß at 22, 26, 46, 66, 96, 156 or 186 days of age. They were autopsied at the end of the 24th hour after initial estrogen treatment. The sensitivity of the uteri to estrogen increased with advancing age and a peak was reached at about 46 days of age when the animals, if intact, would have reached puberty. The uterine sensitivity to estrogen decreased markedly with further increase in age. Similar results were shown when 1.0 µg or 2.0 µg estradiol-17ß per 100 gm body wt. was administered. The duration of postovariectomy period of adult rats did not influence the sensitivity of the uteri to estrogen. It was suggested that under normal conditions the change in uterine sensitivity is as important as the hormonal factor in bringing the female rat to a stage of puberty.
Effects of various sympathicomimetic drugs on renal hemodynamics in normotensive and hypotensive dogs
Authors: Mills Lewis C. , Moyer John H. , Handley Carrol A.
Published: December 2017

The effects of l-epinephrine, l-norepinephrine, phenylephrine, methoxamine, metaraminol and mephentermine on renal hemodynamics were studied in six groups of dogs. Although comparable rises in blood pressure were obtained, there were marked differences in the effects on renal hemodynamics. While infusion of mephentermine led to only slight reductions in glomerular filtration rate and renal blood flow, and only a slight increase in renal vascular resistance, methoxamine produced a marked fall in flow and a marked increase in resistance. The other agents tested had effects which were intermediate between these two. The effects of these same drugs on renal hemodynamics were also compared in dogs made hypotensive by bleeding. While blood pressure increased significantly in all groups, glomerular filtration rate and renal blood flow increased significantly only during infusion of mephentermine, metaraminol and phenylephrine. Since assays relative to the inherent vasodilator properties of these agents revealed epinephrine to be the only agent with marked activity, it seems unlikely that the observed effects were due to this factor. It is concluded that the observed changes were due to a greater reactivity of renal vascular vasoconstrictor adrenergic receptors with certain sympathicomimetic drugs than those of the vasculature in general.
Renal responses of the bullfrog to oxytocin, arginine vasotocin and frog neurohypophysial extract
Authors: Uranga Julia , Sawyer Wilbur H.
Published: December 2017

The antidiuretic responses of bullfrogs to oxytocin, frog neurohypophysial extract and arginine vasotocin are compared. Frog extract and arginine vasotocin injected into the ventral lymph sac are approximately 500 times as potent in inhibiting diuresis in frogs as is oxytocin, if they are compared on the basis of oxytocic units. This observation is consistent with the hypothesis that arginine vasotocin is present in the frog neurohypophysis and accounts for its antidiuretic activity in the frog. Diuresis rather than antidiuresis is occasionally seen in bullfrogs after intravenous injection of these preparations. Diuresis is accompanied by an increase in glomerular filtration rate. The presence of diuresis cannot be correlated directly with changes in arterial blood pressure. The mechanism underlying this diuresis remains obscure.
Lipid absorption, transport and hepatic assimilation studied with electron microscopy
Authors: Ashworth C. T. , Stembridge V. A. , Sanders E.
Published: December 2017

An electron microscopic study of intestine and liver in rats ingesting a high-lipid diet or receiving corn oil by stomach tube was carried out. Studies of the intestinal phase of lipid absorption in rats showed what appears to be the direct transfer of particles across the cell membrane confirming the postulate that some of the process of lipid absorption involves triglyceride particles. Lipid droplets, representing chylomicrons were identified in hepatic sinusoids. They were traced into the pericellular space of Disse, which they had entered through the wide pore spaces in the sinusoidal endothelial cytoplasm. Lipid particles were also observed in different stages of direct transfer across the hepatic parenchymal cell membrane, and their formation of larger cytoplasmic lipid droplets within the cytoplasm of liver cells. This mechanism is proposed as a major device of the body in dispersing the lipemia which occurs after the ingestion of a fat meal.
Ouabain contracture of frog heart: Ca45 movements and effect of EDTA
Authors: Thomas Lyell J.
Published: December 2017

Ethylenediaminetetraacetic acid (EDTA) renders frog heart muscle fibers indiscriminately permeable to Na, K and S35O4 and causes relaxation of contractures induced by ouabain but has no effect on contractures induced by iodoacetate. The contracture induced by iodoacetate under anaerobic conditions can be reversed aerobically either in the presence or absence of EDTA. These observations indicate that the ouabain contracture is not due primarily to an intracellular shift in Na+ or K+ concentration nor to a gross interference with intracellular energy metabolism but could be due to an altered handling of Ca++ by the ouabain-treated muscle. A slightly greater than normal uptake of perfusate Ca45 was found to occur during ouabain contracture but not during exposure to concentrations of the drug causing only positive inotropic effects.
Transfer of Ca45 across intestinal wall in vitro in relation to action of vitamin D and cortisol
Authors: Harrison Harold E. , Harrison Helen C.
Published: December 2017

The transfer of calcium across the intestinal wall of rats was measured in vitro by the device of everted intestinal loops with Ca45 as an indicator. The conditions were developed so that the rate of diffusion of calcium across the intestinal wall as well as active transport against a concentration gradient could be determined. Vitamin D treatment increases the rate of diffusion of calcium across the intestinal wall. This action of vitamin D is exerted along the entire length of the small intestine and is not affected by inhibition of oxidative metabolism. The active transport of calcium on the other hand is localized to the proximal part of the intestine and is dependent on the energy of oxidative metabolism. Cortisol treatment antagonizes the vitamin D effect on the diffusion of calcium and also reduces the active transport of calcium. It is suggested that vitamin D and cortisol influence calcium transport by action on the permeability of cell surfaces to calcium.
Potentiation of the life-maintaining activity of desoxycorticosterone by sodium salts and water
Authors: Swingle W. W. , DaVanzo J. P. , Glenister D. , Rowen R. , Wagle G.
Published: December 2017

Adrenalectomized dogs, symptom-free, are readily maintained by injection of 0.5 mg/day of desoxycorticosterone (DOC) plus a small salt supplement, but fasted animals can not be revived from severe insufficiency by mineralocorticoid. Evidently the Na and water in food potentiates the life-maintaining activity of DOC since their administration readily restores activity and vigor to the prostrate animal. Thus mineralocorticoids plus salt and water can maintain a normal electrolyte pattern in the extracellular fluids by regulating renal excretion and retention of Na, Cl and K but they apparently are unable to mobilize fluid and electrolytes from extravascular sites of starved adrenal insufficient dogs and shift them to the intravascular compartment for maintaining the plasma volume. Glucocorticoids induce recovery of such starved, dehydrated, adrenalectomized animals in absence of exogenous sources of food and water. The presence of oxygen functions at C11 and C17 of adrenal steroids confers upon the molecule ability to mobilize and regulate internal shifts of water and electrolyte between extra- and intravascular compartments.