bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiovascular functions in the dog rewarmed rapidly and slowly from deep hypothermia
Authors: D'Amato H. E. , Kronheim Suzanne , Covino B. G.
Published: December 2017

Heart rate, blood pressure, cardiac output and cardiac minute work were measured in pentobarbitalized dogs prior to induction of hypothermia, at rectal temperatures of 25°C or 20°C and following rapid rewarming in warm water or slow rewarming by wrapping in heated sheeting. During rapid rewarming from either 25°C or 20°C no consistent failure in recovery of normal cardiovascular function was observed, although 1 out of 10 dogs did suffer cardiovascular collapse during rapid rewarming. Slow rewarming from 25° and 20°C resulted in consistent failure of some or all of these functions to recover to prehypothermic levels. Moreover, 5 out of 15 slowly rewarmed dogs suffered cardiovascular collapse during the rewarming process. In five dogs slowly rewarmed from 20°C saline was infused into the superior vena cava. This procedure resulted in moderate increases in blood pressure but dramatic increases in cardiac output and minute work (200% and 270%, respectively), thereby negating myocardial failure as the primary cause of the occasionally observed cardiovascular failure.
Effect of starvation and refeeding on incorporation of C14-amino acids into protein of isolated rat diaphragm
Authors: Wool Ira G.
Published: December 2017

Starvation for 48 hours followed by refeeding for 24 hours increased the incorporation of several C14-amino acids into the protein of isolated diaphragm. Amino acid incorporation was increased by refeeding independent of the nature of the diet, but a high carbohydrate diet produced the greatest increase. The adaptive change in protein synthesis occurred in the absence of the anterior pituitary and its hormones.
Precocious ovarian stimulation following hypothalamic and amygdaloid lesions in rats
Authors: Elwers Mildred , Critchlow Vaughn
Published: December 2017

The effects of neural lesions on the functional development of the reproductive system were studied in prepubertal female rats. Small electrolytic lesions were placed bilaterally in 66 female rats at 18–20 days of age; 42 littermates served as controls, and 7 rats were blank-operated. All animals were weighed two to three times a week and examined daily for vaginal opening. At 33 days of age the uteri, ovaries and adrenals were weighed and prepared for histological study. All brains were examined histologically for lesion localization. Lesions in the anterior hypothalamus or in the medial portion of the amygdaloid complex were associated with precocious ovarian stimulation. With the exception of one lesion in the basal septum and one in caudate-putamen, bilaterally symmetrical lesions in other parts of the brain and asymmetrical lesions have been ineffective. These results are compatible with an anterior hypothalamic mechanism involved in the inhibition of gonadotropin secretion and suggest the inclusion of the medial portion of the amygdaloid complex in this mechanism.
Pharmacological behavior of spinal cord potentials relative to reflex and ascending discharge
Authors: Libet B. , Alberts W. W. , Perryman J. H.
Published: December 2017

The slow negative and positive potentials recorded at the cord dorsum and at an adjacent dorsal root in response to a dorsal root volley were relatively insensitive to mephenesin, morphine, Dial, Nembutal, chloralose, eserine, amyl carbamate and, less clearly, urethane. In the doses used, mephenesin (and, to a lesser extent, morphine) markedly depressed the longer-latency, polysynaptic components of the reflex discharge and of the ascending tract responses in the contraventrolateral and ipsidorsolateral columns. The other drugs affected the monosynaptic reflex as much as or more than the polysynaptic discharge. The carbamates used depressed the monosynaptic reflex in smaller doses with increasing length of the aliphatic chain. The lack of parallelism between behavior of the slow cord potentials and the reflex or ascending discharge is explainable by the hypothesis that the slow potentials result from graded postsynaptic potentials in certain groups of interneurons. The insensitivity to eserine suggests that such postsynaptic potentials are developed at noncholinergic junctions.
Regulation of shivering and nonshivering heat production during acclimation of rats
Authors: Davis T. R. A. , Johnston D. R. , Bell F. C. , Cremer B. J.
Published: December 2017

When cold acclimating rats are treated with diathermy, curare and a combination of both, two main fractions of the increase in cold-induced oxygen consumption can be delineated. First, a fraction which diathermy replaces by virtue of the fact that it, in the intensities used, can raise core temperature without altering the temperature of the skin; therefore this fraction appears to be dependent upon changes in central temperature and is found to persist throughout the period of acclimation investigated. Second, a fraction of cold-induced oxygen consumption which is not replaced by diathermy and which is presumed to be dependent upon changes in skin temperature. By the administration of curare, this second fraction can be separated into two further fractions acting reciprocally depending upon the duration of cold exposure. In the early stages of acclimation, the curare-suppressed fraction of oxygen consumption appears to be entirely due to shivering. As shivering disappears with acclimation, it is replaced by a peripherally regulated nonshivering heat source which eventually takes over all the duties of heat production previously performed by shivering.
8-Azaguanine, 3, 3' -4, 4' -tetrahydroxy-chalcone and purine in experimental shock in the rat
Authors: Janoff Aaron , Zweifach B. W.
Published: December 2017

Two substances, 8-azaguanine (8AG) and 3, 3' -4, 4' -tetrahydroxy-chalcone (THC), believed to be nonoxidized in vivo inhibitors of xanthine oxidase in the rat, were used in an attempt to depress iron-release mechanisms during shock. Purine, a substrate of xanthine oxidase, was administered during shock as a means of stimulating these same mechanisms. No protection was obtained with 8AG and subsequent tests revealed that 8AG failed to depress the release of iron and uric acid both in shocked and untreated rats. The data point, instead, to inhibition of uricase by 8AG in the intact rat and not to inhibition of xanthine oxidase activity. Despite occasional depression of xanthine oxidase activity, THC exacerbated the course of traumatic shock in rats, possibly as a result of interference with pressor amine mechanisms. Purine loads were administered to normal rats and to rats primed with thorotrast. Although purine is known to elevate plasma iron in other species, rats treated with this metabolite were not unusually susceptible to lethal traumatic injury.
Tension response of mammalian muscle to intra-arterial acetylcholine
Authors: Rowley Peter T. , Wells Jay B. , Irwin Richard L.
Published: December 2017

Using isometric tension recording of the tibialis anterior muscle of the cat, the response to intra-arterial acetylcholine injection was studied and compared to the response to electrical stimulation of the nerve. The amount of acetylcholine, the rate of injection and the volume of diluent injected are interrelated factors in the production of tension. Regardless of the amount and concentration of the acetylcholine injected, the contractile response of the muscle has a slower rate of rise and a longer duration than the response from single maximal impulse stimulation to the nerve and a maximal tension less than from a tetanic neural stimulation. The dose-response relationship between the injected acetylcholine and the resultant tension and its modification by curare are described. The steep portion of the dose-response curve was found to occur in most experiments between 0.5 and 6.0 µg. A method of supplying blood to the muscle is described which provides more reliable intermittent arterial occlusion during injection.
Modification of cortical, reticular and hippocampal unit activity by nicotine in the rabbit
Authors: Dunlop C. W. , Stumpf C. , Maxwell D. S. , Schindler W.
Published: December 2017

Of the three regions examined, the hippocampus had the lowest threshold for nicotine effects. Following nicotine injection, regularization of the EEG in all regions was accompanied by increased unit excitability, and during seizures the unit activity was depressed. Modification of neocortical and reticular unit activity without any concomitant EEG changes in these regions was occasionally recorded after nicotine injection. Further experiments indicated that these changes of unit activity were due to alterations in hippocampal excitability elicited by the drug. Electrical stimulation of the hippocampus which evoked regularization and seizure discharges similarly modified the reticular unit excitability, but no conclusive results could be obtained regarding the hippocampal influence on neocortical units.
Polydipsia in the hen following lesions in the supraoptic hypothalamus
Authors: Ralph Charles L.
Published: December 2017

Ablation of the supraoptic region of the hen's hypothalamus by electrolytic lesions resulted in polydipsia in a number of birds. Rates of water consumption were increased, following lesions, by two to three times the initial rate. Although not all hens sustaining lesions in the supraoptic region exhibited polydipsia, lesions elsewhere in the anteroventral hypothalamus uniformly failed to cause increased water consumption.
Magnesium excretion in the dog studied by stop-flow analysis
Authors: Murdaugh H. V. , Robinson R. R.
Published: December 2017

Stop-flow analysis performed in the dog using Mg-28 demonstrated active reabsorption of magnesium in the proximal portion of the distal nephron. ‘Interrupted’ stop-flow analysis failed to document the existence of a renal tubular secretory mechanism for magnesium. During magnesium-loading reabsorption of potassium occurs in the distal nephron despite the presence of hyperkalemia.
Effect of drugs that alter uric acid excretion in man on uric acid clearance in the chicken
Authors: Berger Lawrence , Yü T'sai Fan , Gutman Alexander B.
Published: December 2017

In 43 chickens, the mean Cinulin was 4.7 ± 1.8 ml/min. (1.8 ± 0.8 ml/kg/min.), mean Curate 29.0 ± 14.9 ml/min. (11.3 ± 6.0 ml/kg/min.) and mean Turate 1.30 ± 0.69 mg/min. (0.48 ± 0.24 mg/kg/min.). Tubular secretion accounted for a mean of 81% of the total urinary urate. Probenecid, sulfinpyrazone, zoxazolamine and high dosages of phenylbutazone, all uricosuric in man, reduced urate excretion in the chicken, apparently by suppressing tubular secretion of urate; CPAH also was reduced. Salicylate, in doses uricosuric in man, had no effect on chicken urate excretion. Pyrazinamide and sodium r-lactate, agents which decrease urate excretion in man, did not alter urate excretion in the chicken. PAH loading experiments demonstrated that as TPAH increased, Turate decreased. These latter findings suggest competition of urate and PAH for renal tubular transport in the chicken.
Effects of magnesium and calcium loading on renal excretion of electrolytes in dogs
Authors: Samiy A. H. E. , Brown J. L. , Globus D. L.
Published: December 2017

Effects of intravenous infusion of magnesium and calcium salts on excretion of electrolytes in dogs were investigated by clearance and stop-flow studies. Infusion of these salts, irrespective of the anions, caused a marked increase in the excretion of potassium and a minor change in the urinary excretion of sodium. Stop-flow studies revealed that infusion of magnesium or calcium salts increases the clearance ratios for potassium both in the proximal and the distal samples. These data could be interpreted as indicating that magnesium and calcium loading increase the excretion of potassium by interfering with its reabsorption and/or augmenting its secretion in both proximal and distal segments of the nephron. However, they can be interpreted with equal justification as indicating depression of reabsorption and/or increased secretion of potassium in either the proximal or distal segments. The stop-flow method cannot distinguish between these several possibilities.
Effect of adrenaline on nitrogen excretion in normal rats
Authors: Granitsas A. N.
Published: December 2017

The effect of adrenaline on the urinary excretion of total nitrogen, creatinine and purine metabolites was studied in normal male rats. It was found that adrenaline produces a significant increase in purine metabolites in urine and a marked increase in total nitrogen excretion. This action of adrenaline is not duplicated by cortisone and not inhibited by adrenergic blocking ergot alkaloids; noradrenaline has a less pronounced effect on nitrogen excretion.
Site of origin of plasma triglyceride
Authors: Byers Sanford O. , Friedman Meyer
Published: December 2017

The plasma lipid concentrations 6 hours after injection with p-iso-octyl polyoxyethylene phenol polymer (Triton) were compared in groups of 7–12 rats subjected to surgery. When the gastrointestinal tract alone was removed, plasma lipids were the same as in the sham-operated controls (except for a small cholesterol deficit). Although the rats deprived of liver but still retaining the gastrointestinal tract accumulated some triglyceride and cholesterol, the amount was small compared with that in the viscerectomized rat with a functioning liver, or the sham-operated controls. When both liver plus gastrointestinal tract were removed, lipid values were the same as in normal rats not given Triton. The authors conclude that the liver is the major source of plasma triglyceride.
Changes in membrane potentials, K content, and fiber structure in irradiated frog sartorius muscle
Authors: Darden Edgar B.
Published: December 2017

Changes in membrane potential, K content, and fiber structure were studied in excised frog sartorius muscles that had received massive single doses (50–200 kr) of ionizing radiation. With muscle in normal Ringer's solution at 25°C, the median membrane potential declined and K leakage increased progressively, as measured at intervals, after exposure doses above ∼100 kr; in K-rich Ringer's solution, decline was appreciably slower. In individual irradiated fibers, membrane potentials recorded at different points along a fiber tended to be nonuniform. When subsequent histologic alteration occurred, it often originated as a focal disorganization of structure in a region of minimum membrane potential. Visible pathologic changes resembled in part Zenker degeneration in intact muscle. It is suggested that decline in membrane potential, histologic changes, and increased K leakage are different expressions of the same basic radiation lesion. Radiation-induced changes were markedly retarded by posttreatment storage at 3°C.
Survival and body composition of normal and hypothalamic obese rats in acute starvation
Authors: Montemurro D. G. , Stevenson J. A. F.
Published: December 2017

Female hypothalamic obese rats contained approximately 240% more fat, 10% more protein and 18% more water than did their controls, however ratio total water/fat-free mass remained within normal limits in this frank obesity. At death from starvation, the water, fat-free mass and protein compartments were significantly smaller than those of the controls, the fat compartments were not significantly different. Control rats survived starvation for 16.4 ± 1.3 days, obese rats 42.7 ± 1.8 days ( P < .001). The resting metabolic rates of normal and obese rats in the fed state were not different and both fell gradually throughout starvation. The prolonged survival of obese rats is due primarily to their excess reserve of energy and not to alterations in metabolic rate. As in the fed state, hypothalamic obese rats drank less water during starvation than did the controls. This is thought to result from direct interference with hypothalamic elements regulating thirst and the spontaneous consumption of water.
Conversion of glucose to glycogen after ingestion of a high-carbohydrate diet
Authors: Chari-Bitron A. , Lepkovsky S. , Lemmon R. M. , Dimick M. K.
Published: December 2017

The glycogen content of nine tissues of trained-fed rats was investigated at fasting and at different times after eating with and without water. With the exception of the brain and muscles, the tissues contained little or no glycogen at fasting and accumulated variable amounts during the course of digestion with peak accumulation in most cases 4–7 hours after the commencement of feeding. The brain glycogen did not vary in the rats in spite of the different experimental conditions of this study. The amount of muscle glycogen in the fed rats was the same or slightly more than the amount found in the fasting rats. The fasting liver incorporated C14 substrates into glycogen while it was decreasing in amounts. Fasting muscles incorporated C14 substrates almost as fast as fed muscles indicating that muscle glycogen behaved as an intermediate compound and was metabolized as fast as formed. Accumulation of glycogen in the mesenteric, renal and subcutaneous fatty tissues was decreased by a) feeding without water and b) excessive deposits of fat in the fatty tissues.
Effect of temperature on the heart in the alligator
Authors: Wilber Charles G.
Published: December 2017

Electrocardiograms were taken on 12 alligators, 18–30 inches in length. Some were exposed to elevated temperatures; the resulting ECG's were compared with controls obtained at 22°C, which were as follows: rate, 40/min.; P-R, 0.4 seconds; Q-T, 0.6 seconds; T, 0.24 second, 0.05 mv; QRS, 0.04 second. Heart rate increased with increased colonic temperature. At 34°C there was marked increase in variability of rate. Above 40°C the heart became irregular and was damaged irreversibly. Duration of T decreased with elevated temperature to about 33°C above which T was prolonged. Optimal temperature for the alligator in terms of tolerance and general behavior is between 32°C and 35°C, with a critical maximum of 38°C. Slightly above that temperature the heart became disorganized. The present results suggest that the alligator's temperature preferendum is sound with respect to cardiac well being.
Experimental transfusion of lymphocytes
Authors: Shorter Roy G. , Bollman Jesse L.
Published: December 2017

Lymphocytes, obtained from the intestinal lymph of rats and labeled with radiochromium or radiophosphate, were injected intravenously into rats. Both autogenous and homologous lymphocytes which were motile at the time of injection were used. No appreciable radioactivity became evident in the intestinal lymph until 4 hours after injection, but as much as half of the injected material was recovered in the lymph of the subsequent 24 hours. All the radioactivity disappeared from the blood within a half-hour, and began to reappear within 4 hours to reach maximal activity at about 24 hours. Tissue distribution determined at intervals indicated that 73% of the injected material was in the spleen at one-half hour, and that there was a gradual decrease to 7% by 72 hours. The content in bone marrow decreased from 4.5 to 1.3% at the same time. The thymus gland, lymph nodes, liver and small intestine showed increases over this same period. An active migratory process of lymphocytes is clearly indicated.
Cationic excretion by the dog kidney
Authors: Domer Floyd R.
Published: December 2017

The cells of the renal tubules are known to secrete both organic cations and potassium. A method of demonstrating potassium secretion is to force feed a potassium salt for a period of time and then infuse potassium during a clearance experiment. In these experiments the organic cations, tolazoline (Priscoline), N'-methylnicotinamide (NMN) and mepiperphenidol (Darstine) were force fed to dogs. The effects on cationic excretion during standard clearance experiments before and after this procedure indicated an increased efficiency of the renal tubular handling of Priscoline and NMN but not of Darstine. In animals force fed potassium chloride there was also an increased efficiency in the handling of mecamylamine (Inversine). These results add further evidence to the close interrelationship of the transport systems involved in the secretion of potassium and organic cations by the kidney tubules.
Alloxan diabetes, insulin and adenosine phosphates of liver
Authors: Blaylock Barbara A. , Rothrock Eleanor , Sacks Jacob
Published: December 2017

An overnight fast of rats leads to decrease in the adenosinetriphosphate (ATP) content of the liver, with corresponding increases in the adenosinediphosphate (ADP) and adenosinemonophosphate (AMP) contents. Glucose administration to the fasted animal does not restore the ATP level to that in the fed animal. Alloxan diabetes leads to a moderate decrease in total adenosine phosphates per gram of liver, with marked decrease in ATP content, and absolute increase of AMP above the highest values found in fasted normal animals. A single injection of insulin causes some increase in the ATP content. Diabetic animals fasted overnight show greater ATP levels in the liver than fed ones. It is postulated that the low levels of ATP found in the livers of the diabetic animals may be the rate limiting factor in synthetic reactions, and that insulin in some way accelerates the rate of formation of glucose-6-phosphate without necessarily restoring the ATP concentration to normal levels.
Effect of insulin on potassium efflux from rat muscle in the presence and absence of glucose
Authors: Zierler Kenneth L.
Published: December 2017

Potassium efflux from rat extensor digitorum longus muscle was measured by counting the decrease in K42 in muscle bathed in K42-free solution. The rate constant for K efflux was 0.27 hr.–1 at 37°C and 0.16 hr.–1 at 26°C. Insulin decreased the rate constant for K efflux to 0.22 hr.–1 at 37°C and to 0.09 hr.–1 at 26°C. The effect of insulin on efflux was quantitatively the same when glucose was removed from the bathing solution. From measurement of net change in intracellular K and from measurement of changes in the driving potential for K it is concluded that insulin probably also decreases K influx, but to a lesser degree. However, when half the chloride is removed from the bathing solution, efflux and influx are decreased equally. The data can be interpreted by the hypothesis that insulin increases the positive fixed charge within the muscle membrane.
Comparison of fasting ketosis in pregnant and nonpregnant guinea pigs
Authors: Bergman E. N. , Sellers A. F.
Published: December 2017

It was found that late-pregnant guinea pigs usually developed initially lower blood glucose and markedly higher blood acetone concentrations when fasted for 3 days than did nonpregnant controls. When parturition did not occur, nearly all the late-pregnant animals became ill during this fasting period and died 1–4 days after replacement of the feed. Some animals that underwent parturition after the onset of symptoms died. The symptoms exhibited, effects of fetal maturity and numbers, necropsy findings, fat content of the livers, blood urea nitrogen concentration, reduced output of CO2, ketonemia, early hypoglycemia and, later, euglycemia or hyperglycemia, suggest a marked similarity of this starvation syndrome to ‘pregnancy toxemia’ of ewes and guinea pigs.
Water conservation following prolonged vasopressin administration
Authors: Hollander Walter , Blythe William B.
Published: December 2017

Rats were injected with vasopressin tannate in oil twice daily for 80 days and aqueous vasopressin every 4 hours for the next 3 days. During vasopressin administration, spontaneous water imbibition was less than and serum osmolality remained the same as that of controls receiving peanut oil. After 80 days, renal response to vasopressin was still normal. Beginning 4 hours after vasopressin was stopped, rats were subjected to a 3-day period of water deprivation during which there was no significant difference between previously vasopressin-treated and control rats with respect to: a) urine volume and urine osmolality measured at 12-hour intervals; b) weight loss; c) rise in serum osmolality. No polydipsia developed during 4 weeks after vasopressin was discontinued. It is concluded that prolonged administration of vasopressin to rats does not cause even transient subsequent impairment of water conservation mechanisms including neurohypophyseal release of ADH. This may imply that regulation of ADH secretion does not include a ‘feed-back’ mechanism involving a direct action of circulating ADH on the hypothalamic-neurohypophyseal system.
Supersensitivity to neostigmine and resistance to d-tubocurarine in mice with hereditary myopathy
Authors: Baker Nome , Wilson Leon , Oldendorf William , Blahd W. H.
Published: December 2017

Mice having a hereditary myopathy (dystrophia muscularis) and normal controls were injected with neostigmine and/or d-tubocurarine. Neostigmine (8–19 µg/kg, i.v.) either induced or increased tremors in 16 of a group of 18 myopathic mice. Only 1 of 27 normal mice showed any twitching after the same treatment. Neostigmine when given intraperitoneally in larger doses (21–37 µg/kg) failed to produce twitching in either myopathic or normal mice if the animals were less than 4 weeks old. However, in mice of ages >30 days intraperitoneally administered neostigmine (7 g-18 µg/kg) did produce twitching in dystrophics (12/12) but not in most normals (1/12). A dose of d-tubocurarine (200–250 µg/kg, i.v.), which caused death in 78% of nine normal mice, was lethal to only 22% of nine myopathic mice. The data suggest that muscle from the myopathic mice may share with denervated muscle the property of supersensitivity to acetylcholine.
Ventricular fibrillation during uniform myocardial anoxia due to asphyxia
Authors: Coffman Jay D. , Gregg D. E.
Published: December 2017

Thirty-three anesthetized dogs of varying weights were subjected to complete asphyxia by tracheal occlusion to produce uniform anoxia of the heart. Eleven showed electrocardiographic evidence of ventricular fibrillation while the other twenty-two demonstrated cardiac arrest. The development of ventricular fibrillation correlated with the heavier body and heart weights and with a lower average right atrial serum potassium level as compared to the dogs not fibrillating. Other serum electrolytes, pH, body temperature and sex showed no correlation with the arrhythmia. The importance of the fact that large dogs have a greater susceptibility to develop ventricular fibrillation during uniform anoxia of the heart is discussed in relation to experimental research on dogs and to a current theory of the cause of ventricular fibrillation.
Roles of certain minerals, vitamin E and other factors in the genesis of myocardial fibrosis in mice
Authors: Lee Y. C. P. , King Joseph T. , Visscher M. B.
Published: December 2017

Thirty groups of inbred male C3H mice were studied in relation to the role of dietary minerals and other nutrients in the induction of myocardial damage. It has been found that a level of vitamin E in the diet which was adequate in the presence of ferric phosphate was not adequate in the presence of ferrous sulfate, and became more inadequate when the trace minerals, Co, Cu, Mn, Zn and I were added in amounts provided in the Jones-Foster salt formula. These variables are of critical importance in the development of heart lesions. Reduction of the cod liver oil content of the diet did not prevent the myocardial damage although there was a progressive decline in frequency and increase in the age at onset of the heart failure as the level of the cod liver oil varied from 2, to 1, and to 0%. The incidence of such diet-induced myocardial damage could be greatly reduced by caloric restriction alone. In the absence of vitamin E caloric restriction only delays the onset of myocardial damage. The heart-body weight ratio is increased in mice with myocardial damage as is the water content of the heart. Additions of vitamin E, orally or parenterally at 350 days of age, did not markedly protect mice against later development of the disorder. The age at onset may have been increased by such treatment.
Excitability and electrical response of ischemic heart muscle
Authors: Brooks Chandler McC. , Gilbert Jerome L. , Greenspan Martin E. , Lange Gertrude , Mazzella Hector M.
Published: December 2017

Measurements were made of the changes in the monophasic action potential, excitability, durations of the refractory periods and conduction times in an area of left ventricular muscle during the development of ischemia subsequent to ligation of the ramus descendens anterior. The degree and duration of the ischemia produced varied greatly and effects were related thereto. It was found that action potentials shortened as did the refractory periods; thresholds fell momentarily and then rose progressively as tissue responsiveness failed due to continuing ischemia. Latency of responses increased, the action potentials decreased in amplitude and alternation occurred before the tissue became completely unresponsive. Early re-establishment of a blood supply caused a reversal of the abnormalities. The significance of these changes to the origin of arrhythmias is discussed.
Evidence against an increase in circulating pressor material in renal hypertensive rats
Authors: Blaquier Pedro , Bohr David F. , Hoobler Sibley W.
Published: December 2017

The role played by circulating pressor substances in the renal hypertensive rat was studied by means of an isovolemic cross-circulation technique which is capable of detecting pressor activity in the blood of rats made hypertensive by continuous infusions of renin or synthetic angiotensin. When rats are made hypertensive by release of a completely occluded renal pedicle, this pressure elevation is transferred to an assay rat cross-circulated from the test animal several minutes after the release of the pedicle clamps. It follows that this form of renal hypertension is humorally mediated. On the contrary, when rats with renal hypertension of over 1 week's duration are cross-circulated no rise in blood pressure results in the assay rat, indicating that the maintenance of the elevated blood pressure in renal hypertension in the rat is not dependent on a circulating pressor material.
Some factors influencing O2 consumption of isolated heart muscle
Authors: Whalen William J.
Published: December 2017

Oxygen consumption and resting and developed tension in isolated strips of mammalian myocardium were simultaneously measured in specially constructed chambers. In a resting preparation the O2 consumption increased significantly as the length of the muscle was increased. The evidence suggests that the augmented Qo2 (µl/mg dry wt/hr.) is largely a result of the lengthening, per se, and is not due to the maintenance of tension. In the beating preparation, variations in rate and length accounted for most of the change in the O2 uptake, tension being a less significant factor. The possible relationship of these findings to ‘Starling's law of the heart’ is discussed.
Levels of plasma-bound iron in experimental shock in the rabbit and dog
Authors: Janoff Aaron , Zweifach Benjamin W. , Shapiro Lawrence R.
Published: December 2017

In order to determine whether plasma iron becomes elevated in other forms of experimental shock as it does in hemorrhagic shock, plasma iron was measured in rabbits subjected to lethal doses of endotoxin or infused with lethal amounts of catecholamines, and in dogs in superior mesenteric artery (SMA) occlusion shock. Patterns obtained from these animals were compared with those obtained from rabbits and dogs shocked by hemorrhagic hypotension. In both species hemorrhagic hypotension caused marked elevations in plasma iron, while iron levels were depressed in rabbits treated with endotoxin or lethal infusions of catecholamines and in dogs in shock following SMA-occlusion. The implications of these observations are discussed with respect to differences in tissue oxygen supply in normovolemic and hypovolemic forms of shock and with respect to the presumed role of hyperferremia in the vasculotoxic sequelae of the shock syndrome.
Comparative effects of acidosis induced by acid infusion and CO2 accumulation
Authors: Ligou J. C. , Nahas G. G.
Published: December 2017

Thirteen dogs were paralyzed with succinylcholine and ventilated at constant rate and volume with 100% O2. The control animals were given an i.v. infusion of .15–.30 m lactic acid at the rate of .33 mm/kg/min. for the first 30 minutes and at the rate of .16 mm/kg/min. for the following 30 minutes. After 1 hour pH had fallen from 7.39 to 7.00, diuresis was maintained and mean blood pressure, catecholamine and glucose blood levels were unchanged. By contrast animals with a similar fall in pH produced by CO2 retention presented signs of marked stimulation of the sympatho-adrenal system, such as increased blood pressure, anuria, elevated catecholamine and glucose blood levels. These data indicate the importance of intracellular [H+] changes in the regulation of circulation. The fixed ‘addition acidosis’ produced by lactic acid infusion as described, was corrected by an i.v. infusion of .33 mm/kg/min. of .33 m tris(hydroxymethyl) aminomethane (THAM) which was administered during the second 30-minute period of lactic acid infusion. A similarly produced acidosis required for correction an amount of bicarbonate of sodium double that of THAM.
Effect of adrenal steroids and diethylstilbestrol on growth and fat content of cockerels
Authors: Baum Geneva J. , Meyer Roland K.
Published: December 2017

Graded doses of hydrocortisone, cortisone, corticosterone and diethylstilbestrol were administered to 2-week old cockerels for 7 days and the amount of fat in depots, blood and liver was determined. Hydrocortisone and corticosterone inhibited growth, increased carcass fat and blood and liver lipids. Hydrocortisone is the more potent of the two compounds. Cortisone had no effect on growth or fat content at any of the doses used. Diethylstilbestrol increased blood and liver lipids and stimulated fat deposition without inhibiting growth.
Tactoid formation in deer hemoglobin
Authors: Moon John H.
Published: December 2017

Sickle cell preparations were made on eight Virginia white-tail deer ( Odocoileus virginianus) killed during the 1958–59 hunting season. All preparations showed sickling. Paper electrophoresis of carboxyhemoglobin from these animals revealed identical mobilities and a single hemoglobin component present at pH 8.6. Alkali denaturation of the deer carboxyhemoglobin solution showed that it was markedly resistant to alkali denaturation and that the kinetics of the denaturation were different from that of human cord hemoglobin. Deer carboxyhemoglobin migrated 0.6 x 10–5 cm2/volt/sec.–1 faster than human carboxyhemoglobin A in moving boundary electrophoresis in veronal buffer at pH 8.2. Tactoids were demonstrated in free hemoglobin solution with phase microscopy after concentration of the solution. These particles are very similar morphologically to these prepared from hemoglobin solution containing hemoglobin S.
Abrupt changes of water and sodium excretion in normal and adrenalectomized dogs
Authors: Berlin R. D. , Barger A. C. , Muldowney F. P. , Barnett G. O.
Published: December 2017

An experiment was designed to induce rapid changes in sodium and water excretion. With this procedure normal dogs showed a prompt and marked water diuresis, with an accompanying antinatriuresis. The same dogs, adrenalectomized and maintained on constant adrenal cortical hormone therapy, demonstrated an identical response despite the constancy of steroid concentration, suggesting a ‘permissive’ action of the hormones. When the animals were deprived of therapy for several days the excretion patterns of sodium and water did become markedly abnormal. Acute replacement with hydrocortisone restored the water excretion pattern to normal but did not correct the abnormal sodium excretion pattern. Aldosterone, given prior to and during the experiment, failed to restore either the water or sodium excretion patterns. The results obtained with acute replacement of hydrocortisone and aldosterone were identical with those obtained with hydrocortisone alone.
Autoregulation of intestinal blood flow
Authors: Johnson Paul C.
Published: December 2017

Previous experiments have shown that the arterial vessels of the intestine are responsive to changes in portal venous pressure, with pressure elevation causing arterial constriction. The purpose of the present study was to determine whether these vessels respond in a similar fashion to changes in arterial pressure. In 39 pressure flow studies on segments of terminal ileum, resistance decreased with pressure reduction in 72% of the experiments and increased in 28%. The passive increase in resistance with pressure reduction was seen primarily shortly after the surgical procedure was completed. Thus, it appears that the resistance vessels of the intestine are not ordinarily passively distensible with changes in arterial pressure. As a result of this vascular reaction, the influence of arterial pressure on blood flow is at least partially counteracted. The mechanism of this autoregulation of flow is not a local reflex, a change in interstitial fluid volume, or a change in tone of the intestinal muscle. Changes in concentration of aerobic or anaerobic metabolites, and oxygen tension of the tissues were likewise eliminated. It is concluded that autoregulation of intestinal blood flow is a result of the sensitivity of vascular smooth muscle to change in tension (a myogenic response).
Connective tissue studies. IV: l-ascorbic-1-C14 acid excretion in intact and wounded guinea pigs on varying vitamin C intakes
Authors: von Schuching Susanne , Enns Theodore , Abt Arthur F.
Published: December 2017

Tissues of scorbutic guinea pigs take up a greater percentage of radioactive ascorbic acid following a single injection than do the tissues of guinea pigs on higher vitamin C diets. After wounding, the scar tissue area contains a larger amount of ascorbic acid than distant tissue. Studies of total excretion following a single injection of l-ascorbic-i-C14 acid were conducted at three dietary intake levels, both before and after wounding. Results obtained show that the greatest differences from the preoperative C14 excretion occur during the immediate postoperative period, and after 36 hours the rate constants approximate. Relative to wounding, the guinea pigs on the three different dietary levels react with the same basic pattern; increased deposition of l-ascorbic-i-C14 acid in the scar tissue accompanied by less excretion of C14O2 and a slight increase in C14 activity in the urine. A simplified method for measurement of C14O2 is described. An explanation of human vitamin C requirement and a possible simple assay of ascorbic acid analogues are also suggested.
Pressure-flow studies in the isolated artificial heart-lung perfused mammalian kidney
Authors: Rosenfeld Sheldon , Sellers Alvin L.
Published: December 2017

This study attempts to define some of the physiologic characteristics of the isolated whole blood artificial heart-lung perfused rabbit kidney and describes a modification of an original method previously described. The effects of anesthesia of the kidney donor animal with intraperitoneal ethyl alcohol, intravenous sodium pentobarbital and cervical spinal cord transection (performed on unanesthetized animals) have been compared in terms of renal function and the relationship of renal blood flow to changing perfusion pressures. When spinal cord transection was used, relatively normal levels of renal function were obtained in better than 90% of the experiments. Average values for 12 experiments are: observed renal plasma flow = 1.70; creatinine and p-aminohippuric acid (PAH) clearance = .28 and 1.3 ml/min/gm kidney weight; PAH extraction = 75%; and U:P ratios for creatinine and glucose = 26:1 and 0.1:1. Autoregulation of renal blood flow was demonstrated in a completely denervated kidney perfused with whole blood but was abolished when alcohol anesthesia was used in the kidney donor rabbit. There appeared to be no correlation between the presence or absence of this phenomenon and the level of clearance function achieved by the kidney.
Kinetics of edema formation in rats as influenced by critical doses of dextran
Authors: Kátó L. , Gözsy B.
Published: December 2017

The severity and time of edema formation is characteristically influenced by doses of dextran if injected intravenously into rats. The dose-response curve revealed that small doses of dextrans (0.1–0.8 mg/100 gm) provoke maximal edema formation within 10 minutes, while increasing doses produce less severe edema and delay in its appearance, until a critical dose is arrived at, which provokes no hyperemia and no edema at all. Further increase in dose provokes edema again. The critical dose is relatively sharp and characteristic for each type of dextrans. If antihistamines are injected simultaneously with the critical dose, edema appears with full intensity. Experiments suggest that dextrans contain two fractions with opposite effects, one which provokes the edema formation and another which inhibits the response.
Kinetics of response to epinephrine of isolated rabbit ear
Authors: Stinson R. H. , Burton A. C.
Published: December 2017

A theory for the response of the isolated rabbit ear to various concentrations of catecholamines, based on the reversible formation of a drug-receptor complex, is presented. For application of such a theory the response measured must be primary. The response measured is the increase in driving pressure required to maintain a constant flow of perfusate when a pressor drug is added. This, with a slight correction, is proportional to vascular smooth muscle tension. The agreement between results (50 curves) and theory is very good. For the reaction the over-all equilibrium constant, K, is 8.19 x 106 (S.E.M. = 1.28 x 106), ΔF° = –9.4 Kcal and, from the change in K with temperature, ΔH = 14.5 Kcal; values within the normal biological range. A negative correlation between K and the maximum response of the preparations suggests that the reaction may consist of two, or more, steps. The equilibrium constant for the first step, i.e. formation of the complex, can be roughly estimated as 15.8 x 106.
Role of adrenergic system in thermoglycemic response in baby rabbits
Authors: Chaudhuri Sukhen , Sadhu D. P.
Published: December 2017

Baby albino rabbits housed at 32°C were subjected to an ambient temperature of 42°C and 45°C for a period of 2 1/2 hours. They showed a rise of rectal temperature from 38.0° to 39.0° and 39.4°, respectively; a tachycardia from 235 to 318 and 365, respectively. However, there was no significant change in blood composition, such as erythrocyte or leukocyte count, specific gravity of blood or the hematocrit reading of the ear vein blood. These rabbits showed an increase of blood sugar level from normal 68.5 mg/100 ml blood to 98.7 and 115.1 mg, respectively. This thermoglycemic response is common in birds and has been demonstrated here also in baby rabbits. This response was abolished by the ganglion-blocking agent, pentamethylene-1,5-bis (1-methylpyrrolidinium) hydrogen tartrate and also by the adrenergic blocking agent, ergotamine tartrate. It is concluded that the thermoglycemic response, hyperthermia and tachycardia are mediated by the adrenergic system and are probably evidence of defective thermoregulatory power in baby rabbits.
Fasting gastric contents in the spider monkey
Authors: Smith G. P. , Brooks F. P. , Davis R. A. , Rothman S. S.
Published: December 2017

Five spider monkeys ( ateles) were equipped with chronic gastric fistulae of a modified Thomas type. After an 18-hour fast, gastric contents were collected by dependent drainage with the animals restrained in a chair for 18 experiments and loose in their cages during 17 experiments. Restraint in the chair significantly decreased the acidity of one monkey's gastric contents. Single subcutaneous injections of 0.13–0.27 mg histamine base/kg body weight were given hourly and juice was collected during a 4-hour period. Total acid and pepsin outputs were increased in all 12 experiments. Approximately 2 u of insulin/kg body weight were injected intravenously to produce hypoglycemia. Gastric content was collected after the insulin injection for 3 hours 15 experiments and for 5 hours in 9 experiments. Total acid and pepsin outputs were increased in all experiments, but there was significant variation in the acid response in all the monkeys during the fourth and fifth hours following the insulin injection. These results may have particular significance for studies of nervous control of gastric content in man.
Bile secretion during experimental hyperthyroidism in the dog
Authors: Gans Joseph H.
Published: December 2017

Experimental hyperthyroidism in the dog was accompanied by a significant decrease in the enterohepatic content of bile acids with no significant change in biliary cholesterol output. Plasma cholesterol concentrations decreased consistently in all hyperthyroid dogs. Alterations in the diet were followed by marked changes in bile secretion both in the euthyroid and hyperthyroid dogs. The euthyroid dogs given a diet supplemented with protein and cholesterol secreted greater amounts of cholesterol and bile acids into bile. Hyperthyroidism, induced in dogs given the supplemented diet, was associated with a decrease in the biliary output of both cholesterol and bile acids when compared with the controls given the supplemented unchanged. Changes in the secretion of biliary steroids and sterols during experimental hyperthyroidism in the dog may be the result of a disproportionate increase in the rate of the oxidation of acetate. Confirming earlier investigations in thyroidectomized dogs, dietary constituents may influence plasma cholesterol concentrations in the dog regardless of the state of thyroid activity.
Venae cavae flow pattern in cats: as studied with high-speed cinefluorographic technique
Authors: Lynch Peter R. , Carter Barbara L. , Gimenez Jose , Krisch Robert
Published: December 2017

Movements of Lipiodol droplets were studied in the venae cavae of cats by high-speed cinefluorography at 260 frames/sec. Oscilloscopic tracings of simultaneous cardiac events were recorded on the same movie film. Droplets in the inferior vena cava flowed two to three times faster than in the superior vena cava. The flow pattern of these droplets in the superior vena cava changed between tachycardia and bradycardia, in that they moved predominantly with ventricular systole during tachycardia but moved both in ventricular systole and diastole during bradycardia. No appreciable change was noted in the inferior vena cava between tachycardia and bradycardia.
Stop-flow analysis of ionic transfer in the dog parotid gland
Authors: Langley L. L. , Brown R. S.
Published: December 2017

Page 60: L. L. Langley and R. S. Brown, "Stop-flow analysis of ionic transfer in the dog parotid gland." Substitute corrected figure 1.