bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparative study of the hemodynamic actions of histamine and endotoxin
Authors: Hinshaw Lerner B. , Emerson Thomas E. , Iampietro P. F. , Brake Charles M.
Published: December 2017

The present study is a logical extension of earlier work with the aim of evaluating the relative role of histamine in endotoxin shock. A variety of experiments on 91 dogs were carried out in which the hemodynamic actions of histamine, a histamine releaser (48/80), and endotoxin were compared. Results indicate definite similarities of action in a number of vascular parameters: a) an early increase in portal venous pressure coincident with a decrease in venous return, pooling, and a rapid decrease in systemic arterial pressure and b) eventual increases in foreleg resistance, foreleg small vein pressure, leg weight, and circulating hematocrit. The early responses to endotoxin are greatly altered when 48/80 is administered prior to endotoxin which suggests a common underlying mechanism for the action of each agent. Histamine appears to serve as a triggering device for the sustained release of adrenergic-like agents which superimpose their effects on those of histamine. These findings offer additional evidence for the early release of histamine in endotoxin shock.
Oxytocic action of arachidonic acid under different hormonal environments
Authors: Ichikawa Shigetaka , Yamada Jiro
Published: December 2017

The minimum effective doses of oxytocin and arachidonic acid to produce contractions of pregnant and estrous rat uteri were determined. The pregnant rat uteri were significantly less sensitive to oxytocin and more sensitive to arachidonic acid than the estrous uteri. This mode of action of arachidonic acid on the uterine musculature indicates that the fatty acid may serve as an oxytocic substance for parturition.
Effects of load and duration of tension on pain induced by muscular contraction
Authors: Park Syuk Ryun , Rodbard Simon
Published: December 2017

Pain was induced in the ischemic forearm in more than 300 tests in seven subjects by an exercise which consisted of compression of an air bulb to raise or maintain a mercury column at 50, 100, or 200 mm for periods of 1, 2, 4, or 5.5 sec. The rate of pain development could be correlated with the product ( P) of the number of contractions, square root of the load (in mm Hg), and cube root of the duration of contraction (in sec). Slight pain appeared at a product of about 345 P, moderate pain at approximately 433 P, severe pain at 536 P, and intolerable pain at 626 P. A similar relationship could be shown in maintained contraction provided the total duration was treated as if each 5.5 sec of the maintained contraction constituted a separate contraction. Ischemia of the arm for periods up to 15 min had no effect on product. Recovery from the effect of exercise was complete in 10 min. Simultaneous exercise of the other arm had no effect on the rate of pain development. The results support the concept that muscle pain results from the local accumulation of a slowly diffusible material released during muscle contraction.
Effects of hypophysectomy and growth hormone on utilizable amino acid accumulation
Authors: Snipes C. A. , Kostyo J. L.
Published: December 2017

Hypophysectomy decreased the concentrations of alanine and histidine in the cell water of the rat diaphragm, but had no influence on the levels of these amino acids in plasma. The concentrations of alanine and histidine in the cell water did not vary appreciably from in vivo values, when "intact" diaphragms of either normal or hypophysectomized rats were incubated in Krebs bicarbonate buffer. Addition of l-alanine or l-histidine to the incubation medium resulted in the accumulation of these amino acids in the cell water of both normal and hypophysectomized rat diaphragms. However, muscles or hypophysectomized rats accumulated these amino acids to a lesser extent. When added to the incubation medium, bovine growth hormone stimulated the accumulation of l-alanine and l-histidine by diaphragms of hypophysectomized rats. Thus, these experiments suggest that growth hormone participates in the regulation of utilizable amino acid transport into muscle.
Depression of heme formation and production of free porphyrin in duck erythrocytes
Authors: Klein J. Raymond
Published: December 2017

The effects of a number of substances that depress protoheme formation and affect free protoporphyrin production in duck erythrocytes in vitro were measured. The findings indicate that inhibition of some phase of porphyrin synthesis accounts for depression of heme formation by divalent lead and that inhibition of some phase of the conversion of porphyrin into heme accounts for depression of heme formation by pyridoxine and certain derivatives, adenosine, adenine, chloromycetin, benzimidazole and certain derivatives, and physostigmine. The compounds also inhibit porphyrin synthesis, but under certain conditions pyridoxamine phosphate and physostigmine stimulate porphyrin synthesis.
Mechanism of cardiac arrhythmias induced by diencephalic stimulation
Authors: Manning John W. , Cotten Marion deV.
Published: December 2017

Electrical stimulation of numerous areas in the midbrain reticular formation and in the posterior hypothalamus of the cat increased blood pressure and caused a variety of electrocardiographic changes, including sinus tachycardia, ventricular premature contractions, bigeminal rhythm, A-V dissociation, and ventricular tachycardia. Most commonly, these arrhythmias developed immediately after cessation of diencephalic stimulation but also developed during the period of stimulation in 5 of the 23 cats studied. The arrhythmias disappeared upon cooling and reappeared upon rewarming the vagus nerves. The arrhythmias also were abolished by methylscopolamine, by bilateral vagotomy, or by extirpation of the stellate ganglia. Electrical stimulation of the distal end of the cut right vagus nerve slowed the sinus rate and electrical stimulation of the right stellate ganglion elevated sinus rate, but neither of these procedures caused arrhythmias. Simultaneous stimulation of both the right vagus nerve and the right stellate ganglion, however, caused arrhythmias similar to those observed after diencephalic stimulation. These data are interpreted to indicate that the cardiac arrhythmias evoked by diencephalic stimulation result from the interplay of both sympathetic and parasympathetic influences on the heart.
Renal effect of tris (hydroxymethyl)aminomethane during CO2 load
Authors: Nahas Gabriel G. , Réveillaud René J. , Strauss José , Schwartz Iris , Verosky Mariagnes
Published: December 2017

Renal studies were made on ten dogs treated with an infusion of tris(hydroxymethyl)aminomethane (THAM) during a CO2 load induced by apneic oxygenation. There was a 5 fold increase in diuresis with no significant change in inulin clearance. The urine-plasma osmolal ratio approached unity and there was a rapid elimination of the infusate demonstrating that THAM acts largely as an osmotic diuretic. The clearance of THAM was similar to that of inulin until plasma levels exceeded 19 mEq/liter. At that time the amount of THAM eliminated exceeded the filtered load indicating tubular excretion. The percentage of the filtered load of K excreted increased from 24 to more than 100% and, in spite of a rising pCO2, the tubular reabsorption of bicarbonate reached a plateau after 20 min indicating that when THAM penetrates into the tubular cell, it interferes with the (H+) – (Na+) exchange mechanism. After 1 hr 35% of the THAM given had been excreted and after 4 days up to 93% had been recovered in the urine. The amount of ionized THAM excreted approximated the cationic deficit within 10%. There was a significant net increase in H+ excretion which paralleled the elimination of ionized THAM (R.NH3+).
Maturation, iron deficiency, and ligands in enteric radioiron transport in vitro
Authors: Ruliffson W. S. , Hopping J. M.
Published: December 2017

The effects in rats, of age, iron-deficiency anemia, and ascorbic acid, citrate, fluoride, and ethylenediaminetetraacetate (EDTA) on enteric radioiron transport were studied in vitro by an everted gut-sac technique. Sacs from young animals transported more than those from older ones. Proximal jejunal sacs from anemic animals transported more than similar sacs from nonanemic rats, but the reverse effect appeared in sacs formed from proximal duodenum. When added to media containing ascorbic acid or citrate, fluoride depressed transport as did anaerobic incubation in the presence of ascorbic acid. Anaerobic incubation in the presence of EDTA appeared to permit elevated transport. Ascorbic acid, citrate, and EDTA all enhanced the level of Fe59 appearing in serosal media. These results appear to agree with previously established in vivo phenomena and tend to validate the in vitro method as one of promise for further studies of factors affecting iron absorption and of the mechanism of iron absorption.
Kinetics of procaine-acetylcholine antagonism
Authors: Bloom Floyd E. , Schoepfle Gordon M.
Published: December 2017

The depression in action potential induced by procaine can be arrested or even reversed by acetylcholine in the previously eserinized frog sciatic single fiber preparation. The extent and time course of the reversal are related to the relative concentrations of both procaine and acetylcholine and to the duration of the previous procaine exposure. Resting membrane potential is not affected. Repeated exposures to procaine are characterized by increasingly rapid onset of block, reduced susceptibility to actylcholine competition, and failure of complete recovery after removal of procaine. The time parameters of recovery from procaine depression are independent of the previously applied concentrations of either acetylcholine or procaine. Since acetylcholine has been shown not to cross the nerve membrane, the results are interpreted as indicating that the receptor involved in the competition exists on the external surface of the membrane.
Inhibition of frog (Rana esculenta) antidiuretic action of vasotocin by some analogues
Authors: Morel Francois , Jard Serge
Published: December 2017

The inhibition of the frog antidiuretic action of small amounts of arginine- or lysine-vasotocin by 10–700 times higher amounts of oxytocin and of six of its analogues has been investigated. Oxytocin antagonizes the two tubular actions of the vasotocins (stimulation of water and sodium reabsorptions) but not their glomerular action. The decrease of the relative free water clearance was used as an index of the antidiuretic action of vasotocin. Oxytocin, Ileu8-oxytocin, deamino-oxytocin, and Val3-oxytocin almost completely inhibit the antidiuretic action of vasotocin, whereas lysine-vasopressin, oxypressin, and Phe2-Phe3-Lys8-oxytocin do not. Among the inactive analogues tested, it is suggested that those having a cyclic part identical or closely similar to that of vasotocin are inhibitors by competitive fixation on the reactive site, the different side chain explaining the absence of activity, and that those having a ring different from that of vasotocin (even with an identical side chain) are neither inhibitory nor active because they cannot be bound by the hormonal receptor.
Pineal and ependymal respiration with diverse substrates and inorganic ions
Authors: Quay W. B.
Published: December 2017

Respiration of minced pineals and teased ependymal layers from ventricle IV of adult rats ( Rattus norvegicus) was measured with standard Warburg apparatus and Krebs-Ringer-phosphate media. In studies of the effects of 13 substrates pineal O2 uptake was greatest with succinate and glutamate; ependymal O2 was greatest with glucose, pyruvate, mannose, and lactic acid. In isotonic media lacking substrate but with different Na:K ratios (total concentration = 150 mm), both tissues increased O2 uptake as K concentration was increased from 0 to near 75 mm. At greater concentrations of K, O2 uptake was reduced to a low level, above that when K was lacking, in ependyma, but significantly below even this level in pineal. Presence of glucose led to maximal O2 uptake by both tissues with 125 mm Na and 19 mm K. Pineal respiration was not modified by changes in concentrations of Ca, Mg, PO4, or Cu++. Ependymal respiration was increased by small amounts of Ca, Mg, and increasing amounts of PO4 (0–45 mm), and inhibited by Cu++.
Effect of systemic venous pressure on drainage of lymph from thoracic duct
Authors: Wégria René , Zekert Horst , Walter Kenneth E. , Entrup Richard W. , Schryver Christian De , Kennedy William , Paiewonsky Donald
Published: December 2017

In acute experiments on the anesthetized dog, partial or complete occlusion of the left innominate vein resulting in a rise of pressure in the venous territory into which the thoracic duct drains, commensurate with the venous pressure rise seen in congestive heart failure, reduces the flow of lymph in the thoracic duct. This decrease in thoracic duct lymph flow is due, at least partially, to the accumulation of lymph in the lymphatic system and possibly the intercellular spaces. The present acute experiments suggest the possibility that this factor may play a role in the genesis of the systemic edema of chronic congestive heart failure, although only chronic experiments now under way will permit definitive conclusions.
Cardiovascular response to graded exercise in the sympathectomized-vagotomized dog
Authors: Ashkar Edmundo , Hamilton William F.
Published: December 2017

Seven dogs who ran well on a motor-driven treadmill were completely sympathectomized (including adrenal denervation) and subjected to unilateral vagotomy below the recurrent laryngeal branch. After recovery and retraining, a terminal experiment was performed in which, after completing the vagotomy, direct Fick determinations of cardiac output and continuous recordings of mean arterial pressure, heart rate, and oxygen consumption were made at rest and during increasing exercise The results were compared with those described by Barger et al. ( Am. J. Physiol. 184: 613, 1956) for normal dogs running at smaller speeds and grades. The heart rate of the operated dogs increased from 117 to 134. Barger's normal dogs doubled their heart rate. The A-V oxygen difference increased with work slightly less than Barger's normal dogs but the scatter in both groups was wide, as was the case with the stroke volume. The resting cardiac output was nearly normal in the operated dogs but increased only 34% with exercise, as against 200–300% in Barger's normals. Oxygen consumption increased about twofold as against the expected normal of three- to sevenfold. Peripheral resistance in both groups went down about 40%. The blood pressure in the normal increased substantially while that in the operated dogs fell about 20% to an average of 60 mm Hg.
Energy metabolism in dogs during anesthesia, curarization, or acute arterial hypotension
Authors: Galvão Paulo Enéas , De Magalhães Carlos Alberto E. , Tarasantchi Jacob
Published: December 2017

Forty-two determinations of metabolism (O2 consumption measured by air analysis of the expired air) were made in 14 dogs anesthetized with Dial or Nembutal-morphine (shown not to alter the dog's basal metabolism). Fifty determinations in 14 other dogs (under the same anesthesia) were made before (with spontaneous respiration) and after gallamine curarization (under artificial respiration). The metabolic level after many hours was not significantly altered, either by the anesthesia used or after the gallamine curarization (fair constancy of the arterial pressure was observed in both series of experiments). Therefore, tonus of skeletal muscle and activity of respiratory muscles do not contribute significantly to the total energy metabolism of dogs at rest. The influence of arterial hypotension on metabolism was studied in 18 anesthetized dogs, before (with spontaneous respiration) and several hours after transection of the cervical spinal cord (under artificial respiration and curarization). In all, 71 determinations of heat production were made. The fall in blood pressure, about 50–60% from normal, had no immediate or delayed influence upon the metabolism level.
Brain-to-body ratios and time of maturation of the mouse brain
Authors: Kobayashi Tsukasa
Published: December 2017

Studies on the relationships of brain weight to body weight during development were conducted in 218 mice, and revealed three distinct phases. During the first phase, the ratios are relatively constant. The second phase of short duration is characterized by abrupt reductions. In the third phase, which is the most enduring, the ratios again assume more constant values. The abrupt change in the ratios took place around 14 days of age. It is suggested that the abrupt change in the ratio is, in general, an indicator of the maturation of the brain, because there are several other parameters which approach mature levels around the 15th day. A review of the data on other species supports this suggestion.
Single proximal tubules of Necturus kidney. V: Unidirectional sodium movement
Authors: Oken Donald E. , Whittembury Guillermo , Windhager Erich E. , Solomon A. K.
Published: December 2017

Proximal tubules of Necturus kidneys have been perfused with isotonic solutions of various NaCl concentrations, using the stopped-flow microperfusion technique. At the close of the perfusion period, the tubular fluid was collected for measurement of: Na concentration, Na24 concentration, and freezing point depression. Net H2O movement was measured with C14 inulin. When the tubule is filled with 100 mm NaCl, net Na efflux is 62 ± 13 pmoles/cm2 sec. Since this net Na efflux is directed against an electrochemical potential gradient, it provides direct experimental evidence for active Na transport. Apparent unidirectional Na fluxes have also been calculated from the disappearance of Na24 from the perfused tubule under various experimental conditions.
Measurement of chloride movement across single proximal tubules of Necturus kidney
Authors: Giebisch Gerhard , Windhager Erich E.
Published: December 2017

To study the relationship between chloride fluxes and electrochemical potential difference, single proximal tubules of Necturus were perfused with a modified Ringer's solution containing Cl36. Collected fluid samples were assayed for radioactivity of inulin-C14 carboxylic acid and of Cl36, and chloride concentration was measured by electrometric titration. No significant concentration gradient for chloride was observed while inulin concentration ratios significantly above unity indicated fluid reabsorption. The results indicate that net reabsorptive chloride movement represents only a small fraction of chloride efflux. The relationship between chloride outflux/influx ratio and transtubular electrochemical potential difference is tentatively interpreted as indicating that reabsorptive chloride movement is passive in nature.
Site of potential difference measurements in single renal proximal tubules of Necturus
Authors: Whittembury Guillermo
Published: December 2017

The electrical potential differences from cells and lumina of the proximal tubules of the kidney of Necturus maculosus were measured with micropipette-electrodes, in vivo, and the site of measurement was permanently marked by deposition of carmine in the tissue by iontophoresis from the tip, during recording of each potential difference. The carmine deposits were subsequently localized using serial histological sections. Two negative electrical potential steps were measured, with reference to the interstitial fluid, and the tip position unequivocally marked. a) The potential difference across the peritubular face of the cell, with the microelectrode tip in the cell, averaged –70 mv (cell negative); b) the transtubular potential difference with the tip in the tubular lumen, averaged –21 mv (lumen negative).
Effect of infusion of a protein hydrolysate on blood cell amino acid distributions
Authors: Lund Charles C. , McMenamy Rapier H.
Published: December 2017

The relationships between the concentrations of unbound amino acids in the plasma and erythrocytes, together with amino acid utilization, are studied during the intravenous infusion of a protein hydrolysate in adults. Concentrations of alanine, proline, tyrosine, histidine, valine, phenalanine, leucine plus isoleucine, and urea increase in both the plasma and the erythrocytes. Lysine and methionine concentrations change much less in the erythrocytes than in the plasma. Ornithine and serine plus glycine concentrations in the erythrocytes do not change. It is concluded that amino acids with hydrophobic groups equilibrate readily whereas glycine and amino acids which contain charged or hydroxyl groups equilibrate poorly across the erythrocyte membrane. The changes in glutamine and alanine concentrations during and after infusion suggest that the infused amount of these two amino acids is less than optimum. An expression for amino acid uptake is given.
Lack of facilitation in maze learning by picrotoxin and strychnine sulfate
Authors: Prien R. F. , Wayner M. J. , Kahan S.
Published: December 2017

The purpose of this experiment was to determine the effects of subconvulsant doses of strychnine sulfate and picrotoxin, on maze learning in the hooded rat. At 100 days of age 100 female hooded rats were randomly divided into ten groups of ten animals each. Groups 1, 3, 5, 7, and 9 were injected intraperitoneally with the appropriate solution 20 min prior to each daily trial. Groups 2, 4, 6, 8, and 10 received intraperitoneal injections 1 min after each daily trial. Groups 1 and 2 received 1.00 mg/kg of strychnine sulfate; groups 3 and 4, 0.75 mg/kg of strychnine sulfate; groups 5 and 6, 0.75 mg/kg of picrotoxin; groups 7 and 8, 0.50 mg/kg of picrotoxin; and groups 9 and 10, 1.00 ml/kg of distilled water. Each animal was run one trial a day for 15 days on a 32-unit elevated T maze. A daily record of maze errors was kept for each animal. The results and statistical analyses of this study show that neither strychnine sulfate nor picrotoxin administered before or immediately after training trials affects learning. The results are discussed in terms of their implications for J. L. McGaugh's recent modification of the neural perseveration-consolidation hypothesis.
Seasonal variations in blood volume and circulating metabolite levels of the Husky dog
Authors: Hannon John P. , Durrer John L.
Published: December 2017

The total blood volumes of Alaskan Husky dogs, continuously exposed out-of-doors in the subarctic, were approximately 25% greater in the winter than in the summer. This increase was the summated result of a 38% increase in total erythrocyte volume and a 14% increase in total plasma volume. Chemical analyses of the blood plasma showed large summer to winter increases in total lipids (44%) and phospholipids (40%) and more moderate increases in plasma proteins (28%), cholesterol (24%), and nonprotein nitrogen (14%).
Effect of temperature on incorporation of l-lysine-U-C14 into testicular proteins
Authors: Davis Joseph R. , Firlit Casimir F. , Hollinger Mannfred A.
Published: December 2017

The incorporation of l-lysine-U-C14 into proteins of slices of rat testis, liver, kidney, and spleen has been investigated following a 1-hr incubation period at temperatures of 20, 26, 32, 37.5, and 44 C. In the testis, maximal incorporation of labeled lysine into protein occurred at 32 C, whereas in the liver, kidney, and spleen the maximal incorporation of isotope into protein occurred at 37.5 C. The data obtained indicate that the enzymatic systems involved in the incorporation of labeled lysine into proteins of the rat testis are more heat labile than those of rat liver, kidney, and spleen. It is suggested that the increased heat lability of the protein-synthesizing systems of the testis may offer a partial explanation for the deleterious effects of temperature on spermatogenesis occurring in cases of cryptorchism.
Characteristics of contraction in glycerinated uterine smooth muscle
Authors: Briggs Arthur H.
Published: December 2017

Glycerinated guinea pig uterine fibers developed a maximal tension of 40 g/cm2 in castrated animals and 100 g/cm2 in animals pretreated with estrone or estrone-progesterone in the presence of both adenosine triphosphate (ATP), 5 mm, and Mg, 5 mm. In the absence of Mg, Ca had no effect on contraction induced by ATP (pH 6.5). However, following maximal contraction in ATP and Mg, 1 mm Ca induced a variable slight increase in tension in freshly extracted fibers (4 days-1 month) but not in fibers extracted for over 2 months. At a constant Mg level, 5 mm, the tension developed was a function of the ATP concentration from 0.1 mm to 5 mm (ADP and creatine phosphate had no effect). Above 5 mm, ATP resulted in relaxation which could be prevented by raising the Mg concentration. It was concluded that contraction in uterine muscle was basically similar to contraction in skeletal and cardiac muscle and that these uterine preparations may contain a labile relaxing factor(s) but did not contain ATP restituting systems.
Electromyography of the diaphragm in rabbits
Authors: Boyd William H. , Basmajian John V.
Published: December 2017

A series of 25 adult male rabbits had multiple clip electrodes implanted in their diaphragms at open operation. Following postoperative recovery, the wires from these electrodes were connected to an electromyograph and records were made along with spirometry under normal physiological conditions. The spirometric tracings show four, rather than two, distinct respiratory phases. Just prior to the inspiratory and expiratory phases, a brief but appreciable phase exists during which no air moves into or out of the lungs. These static phases are called pre-inspiratory and pre-expiratory. Diaphragmatic activity continues throughout the respiratory cycle and surveys of the individual recordings reveal beyond question that, although there are many minor variations in degrees of activity between various muscular slips of the same rabbit's diaphragm (even adjacent slips), no obvious general pattern of difference exists. There is no electromyographic peculiarity of behavior in either the lumbar, costal, and sternal parts or for the right and left sides of the rabbit's diaphragm.
High Na content of early embryonic chick heart
Authors: Klein Richard L.
Published: December 2017

Ultrafiltration and fractional centrifugation methods using Na24- and K42-labeled myocardia were employed to demonstrate the fractions of bound and free Na and K in isolated embryonic chick ventricles between 2 and 19 days of development. The data revealed a high percentage of bound Na in the cell-solids fraction of 2- and 3-day hearts. After 5 days Na binding remained constant at 25–30% in the whole homogenate. Bound K remained constant at 25–30% throughout development agreeing with the 70% exchangeability calculated from earlier unidirectional flux experiments. The data confirmed a high degree of Na binding in the early embryonic myocardium and indicated that the large fraction of nonexchangeable ventricular Na at 7 days, measured by flux studies, might depend at least in part on the structural integrity of the myocardial cell rather than on specific binding. Polysaccharide analyses were performed on early embryonic hearts which contained relatively large amounts of cardiac jelly substance. The 2-day heart contains 2–3% acid and 6% neutral polysaccharide. The mucoprotein cardiac jelly is discussed in terms of its Na binding and occluding capacity from the viewpoint of the physicochemical properties of macromolecular systems.
Effect of calcium on uptake of α-aminoisobutyric acid by parathyroid glands
Authors: Raisz Lawrence G. , O'Brien James E.
Published: December 2017

The uptake of α-aminoisobutyric acid (AIB) has been used as a model for the study of amino acid transport in the parathyroid gland. Freshly excised, whole rat parathyroids rapidly took up AIB when incubated in Krebs bicarbonate buffer under 5% CO2, 95% O2 at 37 C, with glucose as the only nutrient. Uptake was inversely proportional to calcium concentration in the medium over the range of 0.75 to 2.25 mm/ liter. Increasing magnesium concentration enhanced AIB uptake. Although AIB uptake was decreased in the absence of phosphate there was no stimulatory effect of increasing phosphate concentration from 0.5 to 3.0 mm/liter. Strontium had an inhibitory effect on uptake but was not as effective as calcium on an equimolar basis. High concentrations of leucine and glycine caused inhibition of uptake as did acidifying the medium to pH 7.1. Growth hormone, vitamin D, parathyroid extract, and hydrocortisone were without effect. AIB uptake of thyroid, kidney, muscle, and liver were not inhibited by calcium. The hypothesis that changes in calcium concentration control parathyroid hormone synthesis by inhibition of amino acid transport at the cell membrane is presented.
Dietary lipids and fatty acid deposition in various calf tissues
Authors: Erwin E. S. , Sterner W.
Published: December 2017

Calves were fed from 5 to 85 days of age a synthetic milk that contained either 10% corn oil (ca. 50% linoleic acid) or 10% methyl myristate. The fatty acid composition of almost all tissues studied was altered to some extent by the change in dietary fatty acids. In the central nervous system, the medulla and spinal cord were resistant, but the peripheral nervous system (sympathetic trunk, brachial plexus, and vagus nerve) profoundly reflected alteration in dietary fatty acids. In peripheral nervous tissue from calves fed corn oil the proportion of linoleic acid increased from 2 to 5% to 25 to 30%. Similarly, in such tissues, myristic acid increased from 2 to 6% to 16 to 43% in methyl myristate-fed calves. Even the fatty acid composition of endocrine glands (pituitary, adrenal, and testis) reflected dietary fatty acids. The fatty acid composition of the skeletal muscle, adipose tissue, and aorta changed with different dietary fats. The greatest change occurred in the cardiac muscle and liver, in which the proportion of linoleic acid increased in the corn oil-fed calves to 50% of the total fatty acids.
Glucuronic acid pathway activity in adipose tissue
Authors: Winegrad Albert I. , Shaw Walter N.
Published: December 2017

Paired samples of rat adipose tissue were incubated with glucose-U-C14 and the effect of unlabeled glucuronolactone on C14O2 production from glucose determined. Glucuronolactone significantly diluted C14O2 production in tissue from starved or alloxan diabetic rats, but not in tissue from normal fed animals. A dilution effect was observed in tissue from fed rats incubated with growth hormone; this effect was also observed with glucose-6-C14, but not with glucose-1-C14. In tissue from starved rats incubated with insulin, glucuronolactone did not dilute C14O2 production from glucose. A dilution effect was observed in tissue from normal rats after the injection of growth hormone, or barbital, which is known to stimulate this pathway in liver. The relative significance of the contribution of the glucuronic acid pathway to total CO2 production from glucose appears to be greater in tissue from starved or diabetic rats than in tissue from normal fed animals; it appears to be increased by growth hormone in vitro or in vivo, but in tissue from starved animals insulin appears to decrease it.
Effect of high oxygen pressure on ground squirrels in hypothermia and hibernation
Authors: Popovic V. , Gerschman R. , Gilbert D. L.
Published: December 2017

The protective role of hypothermia has been demonstrated in barometric depression or hypoxia, in X irradiation, after intoxication with carbon monoxide or after intoxication with other substances, after severe hemorrhage, hyperuremia, or insulin shock. In the present work ground squirrels (hibernators) in three different metabolic states (euthermia, hypothermia, and hibernation) were exposed to 6 atm of pure oxygen and their survival was measured. The hibernating ground squirrels exposed to 6 atm of pure oxygen lived for over 18 hr, the hypothermic ground squirrels for over 6 hr, and the euthermic ground squirrels for a half-hour only. The oxygen consumptions of ground squirrels in three different physiological states—in hibernation, in hypothermia, and in euthermia—were in the proportion of 1:12:40, while the survival times of these animals show an inverse correlation of 33:13:1. Thus it appears that the lowering of body temperature has a protective role against high oxygen pressure mainly because of a decreased metabolism.
Mechanism of negative chronotropic and inotropic effects of some antifibrillatory agents
Authors: Rothman Sol , Yang William C.
Published: December 2017

Three compounds, 1,10-phenanthroline, tripyridine, and quinidine sulfate, which have potent antifibrillatory actions on isolated rabbit atria, were found to have negative chronotropic and inotropic effects on spontaneously beating rabbit atria. During the first 15–20 min, a progressive decrease in rate was observed with 1,10-phenanthroline and quinidine. A second period of rate decline was noted during which some of the atrial electrical complexes appeared to drop out. This second phenomenon was also noted with tripyridine. High amplification recording showed a splitting of the electrical complex with subsequent sudden losses of portions of the complex. Both tripyridine and quinidine produced apparent atrial standstill. During the standstill, amplification of the electrical recording showed regular electrical activity with the absence of contractions. It is concluded that quinidine and 1,10-phenanthroline affect the S-A node initially to produce atrial slowing; whereas, all three compounds produce a later atrial slowing by junctional blockade, presumably at anatomic junctions such as the region between the S-A node and the atrium, or at the intercalated discs within the atrium proper. The negative inotropic effects of all three compounds are in part explained by this junctional blockade.
Effects of bronchoactive agents on static pressure-volume characteristics of dog lungs
Authors: Yoshida Seiichi
Published: December 2017

Static pressure-volume characteristics of the lung in the thoracotomized dog have been studied during continuous infusion of bronchoconstrictor agents into the isolated bronchial arteries, or of sympathomimetic amines into the pulmonary arteries. At inflation pressures less than 20 mm Hg, static airway pressures were higher for a given volume during histamine or acetylcholine infusion than those of the controls. The difference in pressure was marked during inflation from the collapsed state; it was small when inflation was initiated from the end-inspiratory level. When the lung was fully expanded the difference in pressure was insignificant, i.e., drug infusion had no effect on airway pressures. During deflation the pressure-volume curve nearly retraced that of the controls, and pulmonary compliance calculated from the middle third of the deflation curves showed minimal differences. Infusions of epinephrine or norepinephrine into the pulmonary artery did not alter static pressure-volume characteristics. The present findings suggest that bronchoconstriction may lead to closure of some of the pulmonary air spaces by surface tension forces, resulting in a decrease in the number of units sharing a given air volume.
Adenosine triphosphate and electrical activity in chicken vagus
Authors: Dahl Nancy A. , Samson Frederick E. , Balfour William M.
Published: December 2017

Chicken vagus nerves in vitro were placed in an atmosphere of nitrogen; some nerves were first immersed in iodoacetate to inhibit glycolysis. The electrical activity was observed and the nerves then chemically analyzed. The action potential reveals two populations of fibers, presumably nonmyelinated C fibers and small myelinated B fibers. Resting nerves in oxygen have 30 µm ATP/ g protein. In anoxia, ATP concentration and the compound action potential decrease rapidly; this occurs more rapidly when glycolysis is also inhibited. Electrical stimulation during energy deprivation decreases the spike height, conduction rate, and ATP proportionally to the amount of stimulation. The calculated ATP cost of activity is 540 pmoles/impulse per gram wet weight.
Respiratory periodicity in the paralyzed, vagotomized cat: hypocapnic polypnea
Authors: Cohen Morton I.
Published: December 2017

The phrenic nerve discharge was recorded in locally anesthetized, vagotomized cats which were immobilized with gallamine. When the alveolar CO2 tension is reduced, there is a decrease in phrenic discharge, as well as an increase of respiratory frequency, which may become as high as several cycles per second ("hypocapnic polypnea"). Diencephalic section (level of optic chiasma) results in a marked increase of phrenic discharge during hypocapnia; it is therefore concluded that forebrain structures may exert a tonic inhibitory effect on inspiratory discharge. While diencephalic section does not prevent hypocapnic polypnea, mesencephalic section (intercollicular level) eliminates the phenomenon or drastically reduces its extent; it is therefore concluded that at the posterior diencephalic and upper midbrain levels there are systems whose tonic activity tends to increase the respiratory frequency. In naturally breathing, midcollicular decerebrate cats, it was found that CO2 inhalation while the vagi are intact causes an increase of respiratory frequency, whereas after vagotomy it causes a decrease of frequency; thus, vagal afferent input results in reversal of the phenomenon of hypocapnic polypnea.
Vasoactive properties of plasma protein fractions
Authors: Wurzel M. , Bacon R. C. , Kalt R. B. , Zweifach B. W.
Published: December 2017

The capacity of plasma to potentiate norepinephrine (NOR)-induced contractions of the rabbit aortic strip can be attributed to the plasma protein fractions, perhaps almost exclusively to their albumin content. Albumin, 0.2–2 mg/15 ml, potentiated a threshold test dose of NOR from minimal to maximal effect. In the presence of albumin 1–2 mg/15 ml, the threshold dose of NOR was decreased about five to ten times. Albumin, 500 mg/15 ml, did not have a greater potentiating effect. Albumin itself had no contracting ability. The blood of the anesthetized rabbit does not contain sufficient NOR to contract the aortic strip; such concentrations of NOR even in the presence of plasma proteins or albumin were ineffective. The data suggest that NOR does not contribute directly to the maintenance of normal vascular tone.
Acid control by the antrum—effect of antral pH on vagally stimulated antral response
Authors: O'Callaghan W. J. , Kubota N. N. , Harrison R. C.
Published: December 2017

Food was employed to elicit the vagal-antral-gastrin response which was measured by Heidenhain pouch secretion in three dogs. Direct antral stimulation by the food was avoided by making a double-mucosal diaphragm which isolated the antrum from the gastric contents without interfering with its vagal innervation. Antral pH was modified by irrigation in a series of acute stands. In the chronic portion of the experiment the innervated antrum was first isolated with an acid-secreting gastric cuff attached whereas in a succeeding preparation the antrum alone was separated from the gastric contents. In both the acute and chronic experiments changes in antral pH markedly influenced pouch secretion. It is concluded that antral pH greatly modifies gastrin output subsequent to vagal stimulation of the antrum.
Physiological levels and action of dehydroepiandrosterone in Yucatan miniature swine
Authors: Tagliaferro A. R. , Ronan A. M.
Published: December 2017

The biological role of dehydroepiandrosterone (DHEA) and its less active sulphated conjugate DHEAS was investigated in two experiments using Yucatan miniature swine. In experiment 1, plasma levels of both DHEA(S) among males were greater than female pigs that ranged in age from 0.3 to 84 mo old ( P< 0.0001). In males, DHEA(S) were related inversely to serum triglycerides; DHEA was positively related to triglycerides in females ( P < 0.01). In experiment 2, four 2-yr old male pigs, used as their own control, showed a 5% decrease in body weight, 11% increase in energy expenditure, 88% increase in lipid, and 100% decrease in glucose utilization ( P < 0.0001) in response to DHEA vs. placebo treatments when adjusted for body weight. Plasma DHEA(S) were not different between treatment conditions. Glucose tolerance and plasma insulin levels were not different from controls. In vivo response to norepinephrine indicated β-adrenergic sensitivity was altered by DHEA. Present findings suggest DHEA and/or its hormone products are important in modulating energy expenditure and lipid utilization for energy in male animals. The role of DHEA in energy metabolism and the difference between sexes warrant further investigation.
Rectal temperature measurement results in artifactual evidence of selective brain cooling
Authors: Maloney Shane K. , Fuller Andrea , Mitchell Graham , Mitchell Duncan
Published: December 2017

Selective brain cooling (SBC) is defined as a brain temperature cooler than the temperature of arterial blood from the trunk. Surrogate measures of arterial blood temperature have been used in many published studies on SBC. The use of a surrogate for arterial blood temperature has the potential to confound proper identification of SBC. We have measured brain, carotid blood, and rectal temperatures in conscious sheep exposed to 40, 22, and 5°C. Rectal temperature was consistently higher than arterial blood temperature. Brain temperature was consistently cooler than rectal temperature during all exposures. Brain temperature only fell below carotid blood temperature during the final few hours of 40°C exposure and not at all during the 5°C exposure. Consequently, using rectal temperature as a surrogate for arterial blood temperature does not provide a reliable indication of the status of the SBC effector. We also show that rapid suppression of SBC can result if the animals are disturbed.
Metabolic responses to leptin in obese db/db mice are strain dependent
Authors: Harris Ruth B. S. , Mitchell Tiffany D. , Yan Xiaolang , Simpson Jacob S. , Redmann Stephen M.
Published: December 2017

Obese, diabetic C57BL/Ks db/db mice that lack the long-form leptin receptor exhibit no decrease in body weight or food intake when treated with leptin. Here we compared responses to leptin in two strains of db/db mice: C57BL/6J mice that are hyperglycemic and hyperinsulinemic and C57BL/Ks that are hyperglycemic and normo- or hypoinsulinemic. Chronic intraperitoneal infusion of 10 μg leptin/day partially reversed hyperglycemia in C57BL/6J male mice but exaggerated the diabetic state of female mice. Bolus intraperitoneal injections of 40 μg leptin/day did not effect glucose in either strain of male db/db mice, whereas chronic intraperitoneal infusion of 20 μg leptin/day significantly reduced fasting blood glucose in male mice from both strains, especially C57BL/6J mice. Food intake, body weight, rectal temperature, and body fat did not change. Chronic intraperitoneal infusion of 10 μg leptin/day significantly reduced body fat in lean db/+ C57BL/6J but not in C57BL/Ks mice. Thus peripherally administered leptin is active in mice that have only short-form leptin receptors, and the response is dependent on the method of leptin administration and the background strain.
Effect of in vivo fetal infusion of dexamethasone at 0.75 GA on fetal ovine resistance artery responses to ET-1
Authors: Docherty Cheryl C. , Kalmar-Nagy Judit , Engelen Marc , Koenen Steven V. , Nijland Mark , Kuc Rhoda E. , Davenport Anthony P. , Nathanielsz Peter W.
Published: December 2017

At 110–111 days gestation, instrumented fetal sheep were administered saline or dexamethasone (2.2 μg · kg−1· h−1iv) for 48 h. Measurement of fetal blood pressure showed a greater increase in dexamethasone-treated ( n = 6) compared with control ( n = 5) fetuses (7.3 ± 2.3 vs. 0.6 ± 2.3 mmHg, P < 0.05). Fetuses were delivered by cesarean section, and the femoral muscle and brain were obtained under halothane anesthesia. Femoral and middle cerebral arteries (∼320-μm internal diameter) were evaluated using wire myography. Sensitivity to KCl (2.5–125 mM) and the magnitude of the maximal vasoconstriction to 125 mM K+were similar in femoral and middle cerebral arteries from dexamethasone-treated vs. control fetuses. Acetylcholine-induced vasorelaxation was similar in femoral arteries from control and dexamethasone-treated fetuses. Middle cerebral arteries did not relax to acetylcholine. Sensitivity to endothelin-1 (ET-1; 0.1 pM-0.1 μM) and magnitude of the ET-1-induced vasoconstriction were greater in femoral arteries from dexamethasone-treated vs. control fetuses ( P < 0.05). Autoradiographical studies with receptor-specific ligands demonstrated increased ETA-receptor binding, the principal receptor subtype, in femoral muscle vessels ( P < 0.001) but decreased ETA-receptor binding in middle cerebral arteries ( P < 0.01) from dexamethasone-treated compared with control fetuses. Relatively little ETB-receptor binding was evident in all tissues examined. We conclude that hyperreactivity to ET-1, due to increased ETA-receptor binding, may be involved in the dexamethasone-induced increase in peripheral vascular resistance in fetal sheep in vivo.
Chronic effect of insulin-like growth factor I on renin synthesis, secretion, and renal function in fetal sheep
Authors: Marsh Amanda C. , Gibson Karen J. , Wu June , Owens Phillip C. , Owens Julie A. , Lumbers Eugenie R.
Published: December 2017

In the adult, insulin-like growth factor I (IGF-I) increases glomerular filtration rate (GFR) and renal blood flow (RBF) during both acute and chronic treatment. To study its effects on the developing kidney, chronically catheterized fetal sheep (120 ± 1 days gestation) were infused intravenously for up to 10 days with 80 μg/h IGF-I ( n = 5) or vehicle (0.1% BSA in saline, n = 6). In contrast to previous acute studies in adult rats and humans, after 4 h of IGF-I fetal GFR and RBF were unchanged. Fractional sodium reabsorption increased ( P< 0.05). However, by 4 days, GFR per kilogram had risen by 35 ± 13% ( P < 0.05), whereas RBF remained unchanged. Tubular growth and maturation may have occurred, as proximal tubular sodium reabsorption increased by ∼35% ( P < 0.005). Therefore, despite a marked increase in filtered sodium (∼30%, P < 0.05), fractional sodium reabsorption did not change. Although the effects of IGF-I on renal function were delayed, plasma renin activity and concentration were both elevated after 4 h and remained high at 4 days ( P < 0.05). Despite this, arterial pressure and heart rate did not change. Kidneys of IGF-I-infused fetuses weighed ∼30% more ( P = 0.05) and contained ∼75% more renin than control fetuses ( P < 0.005). Thus, in the fetus, the renal effects of long-term IGF-I infusion are very different from the adult, possibly because IGF-I stimulated kidney growth.