bluuebunny/crossref_metadata_2025 huggingface dataset:
Hepatic circulatory changes following endotoxin shock in the dog
Authors: Muller Walter , Smith Louis L.
Published: December 2017

Hepatic arterial and portal venous pressure, flow, and resistance changes have been measured in healthy dogs following the administration of intravenous Salmonella enteritidis endotoxin. The hepatic circulatory changes have been compared with those occurring in total body hemodynamics. Intravenous endotoxin caused an immediate fall in blood pressure, cardiac output, and central venous pressure. There was an abrupt rise in the net portal pressure which was associated with a marked fall in hepatic arterial and portal venous flows following endotoxin administration. There was a gradual reduction in the ratio of portal venous to hepatic arterial flow indicating relative maintenance of the hepatic arterial circulation during the period of endotoxin shock. Hepatic arterial flow increased from 7 to 9% of cardiac output, whereas portal venous flow fell from 15 to 11% of cardiac output following endotoxin administration. The hematocrit showed a progressive rise during the period of observation indicating acute plasma volume reduction. This finding suggests that some of the changes observed in hepatic circulation following endotoxin administration may be due to acute plasma volume reduction.
Pressure-flow relationships in the perfused dog spleen
Authors: Frohlich Edward D. , Gillenwater Jay Y.
Published: December 2017

Isolated and nonisolated preparations of dog spleens were perfused at various rates by means of a blood pump inserted proximal to the splenic artery. Pressures were measured continuously and vascular resistances were calculated. In both preparations vascular resistance decreased as perfusion pressure gradient increased over a wide range (67–313 mm Hg). Pressures and resistances were consistently lower at each perfusion rate in the isolated preparations, presumably due to periarterial nerve transection. The data suggest that the fall in vascular resistance is primarily brought about by a passive opening of closed channels and a further distention of open vessels unrelated to neurogenic factors. There is no evidence that the smooth muscle of the perfused splenic vascular bed actively contracts as flow and pressure increase.
Afferent projections to the lateral cervical nucleus: a microelectrode study
Authors: Morin F. , Kitai S. T. , Portnoy H. , Demirjian C.
Published: December 2017

The lateral cervical nucleus was explored with microelectrodes in lightly anesthetized cats. Extracellular responses were recorded from 160 neurons following physiological stimulation of the ipsilateral side of the body from the neck to the tail. The stimuli activating the neurons were touch, pressure, and joint movement. Neurons responding to touch were more prevalent than neurons responding to pressure on the skin or on deep structures; those responding to joint movements were a small fraction of the neuronal sample studied. For the three stimuli tested, the limbs were more prominently represented than the trunk. Tactile and pressure peripheral fields activating single neurons were of three types: restricted (a few hairs, small areas within one segment of a limb), large (wide areas of the trunk, whole limb), and very large (whole ipsilateral aspect of the body, both limbs). Restricted fields were less numerous than the large fields. One-third of the fields activating single neurons following tactile stimulation was of the very large type. The existence of the very large fields indicated a high degree of convergence of afferents onto neurons of the cervical nucleus.
Effects of zinc, cadmium, and mercury on renal transport systems
Authors: Vander Arthur J.
Published: December 2017

The cysteine salts of zinc, cadmium, and mercury were studied for their effects on sodium, glucose, and p-aminohippurate (PAH) transport in the anesthetized dog by means of clearance technic. PAH Tm was reduced by cadmium and zinc but not by mercury. Glucose Tm was reduced by zinc and mercury but not by cadmium. Pretreatment with dimercaptopropanol completely prevented cadmium inhibition of PAH secretion, but did not alter its enhancement of sodium reabsorption. Zinc did not alter sodium reabsorption at doses which inhibited glucose and PAH transport, but was diuretic at higher doses (3 mg/kg).
Effect of acute alcohol intoxication on steroid output of rat adrenals in vitro
Authors: Kalant Harold , Hawkins Rosemary D. , Czaja Caroline
Published: December 2017

Ethyl alcohol, 2 g/kg in 20% solution, was given to rats by gavage and the adrenals were removed 1 1/2 hr later and incubated in vitro. Their corticosteroid production was not significantly different from that of glands from water-treated or untreated controls. However, when this dose of alcohol was administered by intraperitoneal injection, a significant elevation in adrenal steroid output was observed. Increasing the dose of alcohol to 4 g/kg by stomach tube also evoked an increased adrenocortical response, but when this total dose was divided into two spaced doses, each one of 2 g/kg by stomach tube, 1 1/2 hr apart, no significant alteration in adrenocortical production was observed, despite higher blood alcohol levels and equally deep intoxication. Thus, although the blood alcohol level attained may influence the activity of the adrenal cortex, the rate of change in blood and tissue alcohol levels also seems to be a significant factor in determining whether adrenal cortical stimulation will occur. None of the treatments appeared to modify the relative proportions of the various steroids released.
Ovarian response to gonadotrophins after pretreatment with diethylstilbestrol
Authors: Smith B. D. , Bradbury J. T.
Published: December 2017

Hypophysectomized or intact immature female rats were given follicle-stimulating hormone (FSH), pregnant mare's serum gonadotrophin (PMS), human chorionic gonadotrophin (HCG), or luteinizing hormone (LH) for 3 days, with or without prior administration of diethylstilbestrol for 2 days. Priming with estrogen augmented the ovarian weight response produced by FSH or PMS in both hypophysectomized and intact animals. In contrast, estrogen pretreatment enhanced ovarian growth in intact rats given HCG or LH, but not in hypophysectomized animals similarly treated. Longer periods of priming also failed to augment the ovarian response to HCG in hypophysectomized rats. The ovaries of intact rats given diethylstilbestrol and FSH contained many corpora lutea, whereas luteinization was never noted in hypophysectomized animals similarly treated. Ovarian weight augmentation in the latter was due to enhanced follicular growth throughout the ovary. Estrogen and HCG produced cystic, luteinized follicles in intact rats, in contrast to the lack of such follicular stimulation in hypophysectomized animals. It is concluded that estrogen increases the ovarian response to gonadotrophins by 1) directly stimulating granulosal proliferation, and 2) effecting the release of endogenous gonadotrophins from the pituitary gland.
Lymphatic drainage of the spleen
Authors: Godart Sabine J. , Hamilton William F.
Published: December 2017

The spleens of a series of rats, mice, and guinea pigs were observed by the Knisely transillumination technique with the circulation undisturbed. An injection into the parenchyma of the spleen usually entered a vein and was distributed to the venous sinuses. India ink did not go through the walls of the sinuses but was taken up by phagocytes in these walls. Patent blue dye filled the vessels and immediately diffused into the interstitial space. It was quickly and clearly visible in structures that were taken to be the lymph capillaries and appeared about 5 min later in lymph channels in the same sector of the hilus as the injection. Contractions of the lymphatic wall helped move the dyed lymph into the splenic lymph node and on into the cisterna. On numerous occasions the injecting needle entered a parenchymal lymph space and the injected material appeared immediately and in high concentration in a hilar lymph channel. Only after trauma did red cells or India ink leave the blood stream to appear in the hilar lymph channels. These observations support the theory that the splenic circulation is closed and that as the cells concentrate in the spleen, the fluid drains off through lymphatics. Physical and morphological considerations are advanced which also favor the idea that the splenic circulation is closed.
Mechanisms by which ganglioplegics and atropine enhance cardiovascular responsiveness
Authors: Page Irvine H. , McCubbin J. W.
Published: December 2017

At least four mechanisms contribute to the increased responsiveness to pressor drugs caused by ganglioplegic agents: 1) Elimination of parasympathetic reflexes alone was found to have a prominent effect on pressor responsiveness, especially to norepinephrine. 2) Elimination of sympathetic compensatory reflexes caused the expected increase in responsiveness. 3) Tetraethylammonium had a direct effect on blood vessels of the dog's perfused hind limb that resulted in sensitization to norepinephrine, though not to angiotensin; this direct effect of the ganglioplegic was similar to that produced by surgical denervation. 4) Tetraethylammonium caused enhancement of response to epinephrine but not to norepinephrine in pithed cats and this effect seems best explained by a blocking action of the ganglioplegic on adrenergic vasodilator receptors. Because of the participation of these different mechanisms, ganglioplegics and surgical denervation do not necessarily affect pressor responsiveness in the same manner. Additionally, the different mechanisms involved account for the various degrees of augmentation of response to different pressor drugs since the latter have their major actions on different portions of the cardiovascular system. Responsiveness may vary greatly during a single experiment and also from day to day; this variability is due in large part to the nervous system since it is abolished by cervical section of the spinal cord.
Mechanism by which dietary protein enhances renal concentrating ability
Authors: Manitius Andrzej , Pigeon Gilles , Epstein Franklin H.
Published: December 2017

Renal ability to concentrate nonurea solutes in the urine is improved in dogs by feeding protein. This effect is most apparent during osmotic diuresis induced by mannitol and, though partially explicable by increases in GFR, the data suggest that other factors are also involved. The enhanced concentrating ability of protein-fed dogs is probably related to an increased concentration of both sodium and potassium in the renal papilla.
Effects of certain quinones on renal excretion of sodium
Authors: Weinstein Stephen W. , Kessler Richard H.
Published: December 2017

Coenzyme Q (Q10), an essential of the electron transport system, is located between flavoprotein and the cytochromes. Coenzyme Q consists of a benzoquinone nucleus, having one methyl, an aliphatic and two methoxy constituents. We have attempted to inhibit renal coenzyme Q by the administration of several structural variants directly into one renal artery. Ureteral urines were collected separately for measurement of sodium excretion and renal clearances. Unilateral natriuresis was observed only with aqueous soluble benzoquinones in the oxidized state. The infusion of .001 mmole of one such compound (Q0) was sufficient to block reabsorption of 17% of the filtered sodium load. Natriuresis did not occur with either reduced quinones or those having a long-chain aliphatic constituent. A moderate increase in the renal clearances of creatinine and PAH was typically, but not invariably, observed. These results suggest that Q0 blocks the electron transport system and, therefore, some fraction of sodium reabsorption by competitively inhibiting coenzyme Q. This effect may be mediated through energy metabolism.
Critical oxygen tensions in newborn, young, and adult mice
Authors: Cassin S.
Published: December 2017

Critical oxygen tensions of newborn, young, and adult mice are presented. At neutral environmental temperature, oxygen consumption of newborn mice is unaffected by reducing the oxygen tension of inspired air to 85 mm Hg. Five-day-old mice, at neutral environmental temperature, tolerate a decrease in ambient oxygen tension to 100 mm Hg without a depression of oxygen consumption. Adult mice behave in a qualitatively similar fashion. When the ambient temperature is lowered below neutral, the mice are unable to maintain a constant oxygen consumption if hypoxia is induced. It appears as though the depression of oxygen consumption during hypoxia is linearly related to the hypothermic increment to metabolism: the greater the extra oxygen consumption, the more readily it is reduced. Although the newborn mouse is unable to combat hypothermia effectively, it does respond to mild hypothermia for short periods by increasing its rate of oxygen consumption. Evidence is presented of a rapid maturation of temperature controlling mechanisms during growth.
Response of salt-loaded rats to abrupt withdrawal of salt
Authors: Fordham Christopher C. , Newton Margaret
Published: December 2017

This study was designed to determine whether transient salt wasting follows the abrupt withdrawal of a salt load in rats. Two groups of 30 rats were pair fed an electrolyte-free diet by gavage. One group received 2.5 mm/day of sodium chloride, the other 15 mm/day; both were given 1 mm/day of potassium. After 55 days, salt was withdrawn and the animals sacrificed at several-day intervals. In part I, specimens of aortic blood and skeletal muscles were obtained for chemical analysis, and the adrenal glands were excised for histologic study. In part II, carcass values for sodium and chloride were obtained. The results were: a) There was no evidence of impaired sodium conservation following abrupt salt withdrawal. b) Histologic study of the adrenal cortices revealed flattened glomerulosa zones in the high-salt group and a striking sequential increase in width following salt withdrawal. Evidence of a renal salt-wasting defect following the abrupt removal of a sustained salt load in rats could not be demonstrated.
Effect of thyrotropin on fractional blood flow of chick thyroid gland
Authors: Solomon David H. , Prujan Ross L. , Triplett H. Wayne
Published: December 2017

The effect of thyrotropin (TSH) on the blood flow of the chick thyroid has been estimated by the distribution of Rb86. Mean thyroidal blood flow estimated from the 30-sec Rb86 uptake was 4.60% of cardiac output/g of tissue. During the 1st hr after the intracardiac administration of TSH, there was no effect on the thyroidal blood flow fraction; at 2 hr there was a significant response; by 4 hr the blood flow fraction had doubled. The response then gradually ebbed and disappeared by 24 hr. The long latency of the hyperemic response to TSH is interpreted as indicating that hyperemia is secondary to earlier metabolic activation. Of the various consequences of TSH action, only those with similarly long latencies, such as enhancement of iodide uptake, could possibly be dependent on the hyperemia. The thyroidal blood flow fraction remained constant during growth from 1.5 to 30 days of age, while the relative thyroid weight declined sharply. TSH produced its characteristic effect at all ages studied.
Effect of sodium pentobarbital anesthesia on plasma volume of adrenalectomized dogs
Authors: Swingle W. W. , Swingle A. J.
Published: December 2017

Pentylenetetrazol-shocked, adrenalectomized dogs are unable to raise their lowered plasma volumes when fed a low-sodium diet despite administration of large doses of deoxycorticosterone. The plasma volume rises to preshock levels following injection of glucocorticoids or when the animals are anesthetized with pentobarbital. The plasma volume again decreases to shock levels on recovery from the anesthetic. Dogs exhibiting symptoms of adrenal insufficiency react similarly; the volume rises to normal level under barbiturate anesthesia and falls to the insufficiency level when the anesthetic wears off. Although the plasma volume returns to normal under anesthesia, the arterial pressure of the adrenal-insufficient dogs continues to fall and the plasma potassium to rise. Plasma volume changes evidently have no survival value unless accompanied by increased cardiac and renal efficiency and a sustained blood pressure such as occurred in the deoxycorticosterone-treated animals. Increased plasma volume induced by pentobarbital is apparently due to strong vasodilating properties of the drug. Presumably it relieves the vasoconstriction and opens large areas of closed microcirculatory beds thereby releasing sequestered plasma dammed up at the periphery of the vascular tree.
Stimulation parameters for cardiovascular responses from medulla and hypothalamus
Authors: Wilkus Robert J. , Peiss Clarence N.
Published: December 2017

Electrical stimulation was carried out in the medulla and hypothalamus of 33 vagotomized cats anesthetized with alpha-chloralose. A wide range of stimulation frequencies was used at pulse durations of 2.0, 0.2, and 0.02 msec. The lowest frequency at which the majority of animals reach a maximal response in heart rate or blood pressure was 100 cycles/sec at all three pulse durations. At 2 msec pulse duration, the response declined by 30% at 225 cycles/sec. At pulse durations of 0.2 and 0.02 msec, 30% decline in response occurred, respectively, at 1,040 and 1,250 cycles/sec. The response curves were essentially similar for both heart rate and blood pressure. Strength-duration curves, using a 3% change in heart rate as a threshold response, showed a similarity in the curves for fibers mediating sympathetic acceleration and those mediating sympathetic inhibition of heart rate. The decline in response at high frequencies does not appear to be due to transmitter depletion. The basis for optimal frequency of 100 cycles/sec and for declining responses at higher frequencies is discussed.
Measurement of capacity of biliary tree in rats
Authors: Barber-Riley G.
Published: December 2017

A method is described for measuring the capacity of the normal and of the distended biliary tree. The method depends on the use of dyes rapidly excreted in the bile, which are used as marker substances, and is here applied to rats. The use of an alternative suitable dye, or large alterations in the quantity injected, produced in most cases only small changes in the measured capacities. The measured capacity of both the normal and of the distended biliary tree was found to be proportional to the liver weight, and was altered by an expected amount when a lobe of the liver was functionally removed. The measured extra capacity produced by obstruction of the common hepatic duct was similar to that found using another method. The reliability of the method and some probable errors are briefly discussed. It is concluded that measurements made in this manner might be used to examine the biliary tree during short periods of obstruction.
Actomyosin-like protein of arterial wall
Authors: Filo Ronald S. , Ruegg J. Caspar , Bohr David F.
Published: December 2017

A structural protein is extractable from hog carotids in solutions of low ionic strength (0.05 m KCl + 0.02 m histidine buffer). The following procedures cause precipitation of this protein: 1) standing 12 hr at 2–4 C, 2) dialysis against 0.05 m KCl, or 3) addition of 10 mm CaCl2. The crude preparation obtained by any of these precipitation procedures fails to show superprecipitation on the addition of ATP, but when dissolved in 0.6 m KCl it does demonstrate a viscosity change on the addition of ATP and is capable of ATPase activity. If this crude preparation is purified by repeated calcium precipitation and dialysis against 0.05 m KCl, it then shows the following characteristics typical of actomyosin: 1) superprecipitation, 2) reversible viscosity change on addition of ATP, and 3) ATPase activity characteristically influenced by calcium, or magnesium, or ionic strength. We conclude that this structural protein from hog carotid is an actomyosin-like protein involved in a standard contractile system, and its initial high solubility at low ionic strength may be due either to a reduction in bound calcium or to the presence of an unusually effective solubilizing factor which, like relaxing factor, can be inhibited by calcium.
Effects of hormones on Na and H2O transport and on phospholipid metabolism in toad bladder
Authors: Hestrin-Lerner Sarah , Hokin Lowell E.
Published: December 2017

Incubation of tied paired lobes of bladder from Bufo marinus with 0.025–0.25 U/ml of oxytocin led to appreciable stimulations of both sodium transport and of water transport from the mucosal (luminal) to serosal side. Incubation with aldosterone led to a very slight stimulation of sodium transport, which was statistically significant, in one out of three series. P32 from orthophosphate was incorporated into phosphatidic acid, phosphatidyl ethanolamine, phosphatidyl choline, and phosphatidyl inositol. There were no statistically significant stimulations in the incorporation of P32 into phosphatidic acid, phosphatidyl choline, or phosphatidyl inositol at any concentration of oxytocin. However, there was a statistically significant stimulation of P32 incorporation into phosphatidyl ethanolamine with 0.025 U/ml oxytocin. There was a statistically significant inhibition in incorporation in phosphatidyl choline and phosphatidyl inositol with 0.25 U/ml oxytocin. Cholinergic agents did not produce statistically significant stimulations of either water or sodium transport in toad or turtle bladders, but they led to significant stimulations of incorporation of P32 into some of the phosphatides (phosphatidic acid, phosphatidyl choline, and phosphatidyl inositol in the toad bladder, and phosphatidic acid and phosphatidyl inositol in turtle bladder). On the basis of the fine structure of the epithelium of the toad bladder it is suggested that the phospholipid effect in response to cholinergic agents may be related to stimulation of the secretion of an organic material by the epithelial and/or goblet cells.
Venous and arterial responses to norepinephrine in dogs treated with reserpine
Authors: Abboud Francois M. , Eckstein John W.
Published: December 2017

Experiments were done to see if the effects of norepinephrine upon veins, arteries, and small vessels are augmented in dogs after treatment with reserpine. With intra-arterial injection of increasing doses of norepinephrine into the perfused foreleg there were progressive increments in total, arterial, small vessel, and venous resistances. In animals treated with reserpine the increments in total and small vessel resistances were greatly augmented while increments in segmental arterial resistance were increased only slightly. The venous responses in these treated dogs were not augmented. Similar effects on segmental resistances were noted with infusion of norepinephrine into a systemic vein. The vasoconstrictor effect of tyramine was reduced in treated dogs and was restored after intra-arterial and intravenous norepinephrine. The results indicate that veins do not participate in the increased vascular responsiveness to norepinephrine which occurs in forelegs of dogs after treatment with reserpine.
Effects of inanition, semistarvation, and protein-free diets on serum proteins
Authors: Weimer Henry E. , Godfrey James F.
Published: December 2017

The effects of inanition, semistarvation, and protein-free diets on the partition of serum proteins in adult, male, Sprague-Dawley rats was investigated following weight losses of 12, 26, and 33%. The quantitative changes in the serum protein fractions under the various types of nutritional stress showed significant differences. The albumin, α1- and γ-globulin fractions decreased significantly in the rats on the starvation regimen, while the semistarvation diet caused major alterations in the α1- and ß-globulins. Feeding a protein-free diet elicited the greatest decline in total serum proteins, reflecting the changes in the albumin, α1-, and α2-globulin fractions. The conclusion was drawn that the electrophoretic fractions of serum do not respond in a uniform and nonspecific manner to diverse nutritional stresses.
Mast cells and histamine concentration in muscle and liver of dystrophic mice
Authors: Bois Pierre
Published: December 2017

The distribution of mast cells in muscle and liver of dystrophic mice was studied; histamine and histidine decarboxylase activity was also measured in the same tissues. Mast cells were significantly more numerous in dystrophic muscles. On the other hand, very few cells could be counted in the liver of either control or dystrophic animals. Histamine concentration was higher in muscle and liver of dystrophic mice; no visible increase in histidine decarboxylase activity could be measured by the methods used. It is concluded that histamine-binding capacity is increased in some tissues of dystrophic mice.
Intestinal transport of tryptophan and its derivatives
Authors: Cohen Linda L. , Huang K. C.
Published: December 2017

The intestinal transport of l- and d-isomers of tryptophan and ten derivatives were studied in everted intestinal sacs of golden hamsters. It was found that l-tryptophan, 4-CH3-, 5-CH3-, and 6-CH3-dl-tryptophan, and N-chloroacetyl-l-tryptophan were transported against a concentration gradient and the d-isomer, 5-OH- and 5-benzyloxyl-dl-tryptophan, N-acetyl-l- and N-2,4-dinitrophenyl-dl-tryptophan, tryptamine and 5-OH-tryptamine were not transported. The rate of l-tryptophan transport was much greater than that of the methyl derivatives and N-chloroacetyl-derivative. The transport reached saturation at 3 mm concentration and was inhibited in presence of 6 mm of l-tyrosine or l-phenylalanine. Kinetic study showed that this inhibition was a competitive one. Studies with H3-dl-tryptophan have shown that the transport mechanism was mainly located in the mucosal, not the serosal side. Replacement of Na+ ion either by Li+, K+, or choline in either mucosal or both sides, inhibited the tryptophan transport. Replacement of chloride by sulfate did not show any inhibitory effect.
Sympathetic function and development of temperature regulation
Authors: Wekstein David R.
Published: December 2017

Experiments were performed to determine the role of the sympathetic nervous system in the maturation of temperature regulation in the preweanling rat. Animals 6–16 days of age were placed in a 15 C air environment. The time required for their colonic temperatures to drop from 30 to 20 C was taken as an index of cooling rate. Reserpine, pentolinium, and nerve-growth-factor antiserum were used to evaluate autonomic function. None of these blocking agents influenced the rate of cooling of the 6-day-old animal. In the 16-day-old animal the same agents had a pronounced effect, such that control animals did not cool, while animals that had received reserpine cooled at a rate of 0.18 C/min, animals that had received the pentolinium cooled at a rate of 0.07 C/min, and animals that had received the antiserum for the first 5 days of life cooled at a rate of 0.15 C/min. This study indicates that the sympathetic nervous system is concerned with the development of homeothermy in the rat.
Response of pulmonary circulation of resting, unanesthetized dogs to acute hypoxia
Authors: Thilenius Otto G. , Hoffer Paul B. , Fitzgerald Robert S. , Perkins John F.
Published: December 2017

By means of chronically implanted vinyl catheters, pressures in aorta, pulmonary artery (PAP), left atrium (LAP), and intrapleural space (by capsule) were recorded simultaneously and continuously, together with cardiac output (Q) by dye-dilution technic every 2 min, in unanesthetized, unsedated trained dogs for 1 hr during breathing of air and low oxygen mixtures (6–15%) via a chronic tracheostomy. In nearly all of 54 experiments on 5 animals there were striking responses to hypoxia, consisting of a marked rise in PAP (up to 120%), in Q (up to 75%), in pulmonary vascular resistance (PVR) (up to 200%), and of a significant fall in LAP. In some animals these changes were not maintained throughout hypoxia. The PVR usually returned toward normal first, followed by the PAP, while Q remained elevated. The time sequence of these events varied in different animals. Effects of the same magnitude as in hypoxia accompanied restlessness caused by stress, but fluctuated markedly, were of shorter duration, and could largely be climinated by providing quiet surroundings and by avoiding prolonged experiments. It was concluded that active vasoconstriction occurs in the pulmonary vascular bed during acute hypoxia (breathing of 6–15% O2) in the intact, unanesthetized dog. Furthermore, normal values for PAP, Q, and PVR for the resting, waking dog are reported.
Alterations in chemical composition of canine heart after sympathetic denervation
Authors: Jellinek Max , Kaye Michael P. , Nigh Charles A. , Cooper Theodore
Published: December 2017

Sympathetic denervation of the canine heart, which is extensive enough to insure depletion of myocardial catecholamines, results in an increased accumulation of myocardial fat and carbohydrate substances. Myocardial histamine, ubiquinone and nitrogen contents are unaffected. These observations provide additional evidence for the participation of the autonomic nervous system in the regulation of cardiac metabolism.
Role of ETA receptors in experimental ANG II-induced hypertension in rats
Authors: Ballew Jennifer R. , Fink Gregory D.
Published: December 2017

The objectives were to determine if ANG II-induced hypertension is maintained by activation of endothelin type A (ETA) receptors by endogenous ET-1 and if this effect is influenced by salt intake. Male rats were maintained on high sodium intake (HS; 6 meq/day) or on normal sodium intake (NS; 2 meq/day). Hypertension was produced by intravenous infusion of ANG II (5 ng/min) for 15 days. Five-day oral dosing with the selective ETA-receptor antagonist ABT-627 (∼2 mg · kg−1 · day−1) reduced mean arterial pressure (MAP) to baseline levels in rats on HS receiving ANG II infusion, but it did not affect MAP in normotensive HS controls. In rats on NS, ABT-627 only transiently decreased MAP in rats receiving ANG II and slightly reduced MAP in normotensive controls. ABT-627 produced mild retention of sodium and water in NS rats receiving ANG II, but not in any other group. These results indicate that ET-1 plays a role in ANG II-induced hypertension via activation of ETAreceptors and that this role is more prominent in rats on HS.
Sleep is differently modulated by basal forebrain GABAA and GABAB receptors
Authors: Manfridi Alfredo , Brambilla Dario , Mancia Mauro
Published: December 2017

There is evidence that GABA plays a major role in sleep regulation. GABAA receptor agonists and different compounds interacting with the GABAA receptor complex, such as barbiturates and benzodiazepines, can interfere with the sleep/wake cycle. On the other hand, there is very little information about the possible role of GABAB receptors in sleep modulation. The nucleus basalis of Meynert (NBM), a cholinergic area in the basal forebrain, plays a pivotal role in the modulation of sleep and wakefulness, and both GABAA and GABABreceptors have been described within the NBM. This study used unilateral infusions in the NBM to determine the effects of 3-hydroxy-5-aminomethylisoxazole hydrobromide (muscimol hydrobromide, a GABAA receptor subtype agonist) and β-(aminomethyl)-4-chlorobenzenepropanoic acid (baclofen, a GABAB receptor subtype agonist) on sleep parameters in freely moving rats by means of polygraphic recordings. Muscimol (0.5 nmol) and baclofen (0.7 nmol) induced an increase in slow-wave sleep and an inhibition of wakefulness. Muscimol, but not baclofen, also caused a decrease in desynchronized sleep parameters. The results reported here indicate that 1) the NBM activation of both GABAA and GABAB receptors influences the sleep/wake cycle, and 2) GABAA but not GABAB receptors are important for desynchronized sleep modulation, suggesting that the two GABAergic receptors play different roles in sleep modulation.
Arachidonate dilates basilar artery by lipoxygenase-dependent mechanism and activation of K+channels
Authors: Faraci Frank M. , Sobey Christopher G. , Chrissobolis Sophocles , Lund Donald D. , Heistad Donald D. , Weintraub Neal L.
Published: December 2017

Dilatation of cerebral arterioles in response to arachidonic acid is dependent on activity of cyclooxygenase. In this study, we examined mechanisms that mediate dilatation of the basilar artery in response to arachidonate. Diameter of the basilar artery (baseline diameter = 216 ± 7 μm) (means ± SE) was measured using a cranial window in anesthetized rats. Arachidonic acid (10 and 100 μM) produced concentration-dependent vasodilatation that was not inhibited by indomethacin (10 mg/kg iv) or NG-nitro-l-arginine (100 μM) but was inhibited markedly by baicalein (10 μM) or nordihydroguaiaretic acid (NDGA; 10 μM), inhibitors of the lipoxygenase pathway. Dilatation of the basilar artery was also inhibited markedly by tetraethylammonium ion (TEA; 1 mM) or iberiotoxin (50 nM), inhibitors of calcium-dependent potassium channels. For example, 10 μM arachidonate dilated the basilar artery by 19 ± 7 and 1 ± 1% in the absence and presence of iberiotoxin, respectively. Measurements of membrane potential indicated that arachidonate produced hyperpolarization of the basilar artery that was blocked completely by TEA. Incubation with [3H]arachidonic acid followed by reverse-phase and chiral HPLC indicated that the basilar artery produces relatively small quantities of prostanoids but large quantities of 12(S)-hydroxyeicosatetraenoic acid (12-S-HETE), a lipoxygenase product. Moreover, the production of 12-HETE was inhibited by baicalein or NDGA. These findings suggest that dilatation of the basilar artery in response to arachidonate is mediated by a product(s) of the lipoxygenase pathway, with activation of calcium-dependent potassium channels and hyperpolarization of vascular muscle.
Moderate levels of ethanol induce expression of vascular endothelial growth factor and stimulate angiogenesis
Authors: Gu Jian-Wei , Elam Jesse , Sartin Amanda , Li Wen , Roach Raymond , Adair Thomas H.
Published: December 2017

Alcohol abuse has a negative impact on human health; however, epidemiological studies show that moderate consumption of ethanol (EtOH) reduces the risk of coronary heart disease, sudden cardiac death, and ischemic stroke. The mechanisms for these reductions in cardiovascular disease are not well established. Using cultured coronary artery vascular smooth muscle cells, we found that moderate levels of EtOH (10 and 20 mM) caused dose-related increases in both vascular endothelial growth factor (VEGF) mRNA (Northern blot) expression (1.9- and 2.6-fold) and VEGF protein (ELISA) expression (19 and 68%) compared with control ( P < 0.05). EtOH at 0.25 g · kg−1· day−1(7 days) increased VEGF mRNA expression by 1.48-fold over control, and increased vessel length density from 3.9 ± 0.7 (control) to 6.0 ± 0.3 mm/mm2( P < 0.05) in chick chorioallantoic membrane (CAM). We conclude that moderate levels of ethanol can induce VEGF expression and stimulate angiogenesis in chick CAM. Therefore, the results provide a theoretical basis for speculating that the cardiovascular-protective effects of moderate alcohol consumption may be partly mediated through VEGF-induced angiogenesis.
Ontogeny of humoral heart rate regulation in the embryonic mouse
Authors: Porter George A. , Rivkees Scott A.
Published: December 2017

Catecholamines, acetylcholine, and adenosine are known to influence cardiac function, yet the effects of these agents on mammalian embryonic myocardium are largely unknown. To address this issue, we compared the chronotrophic effects of adenosinergic, adrenergic, and muscarinic agents on cultured murine embryos from postcoital day (PC) 8.0, when the fusing heart tubes first begin to beat, to PC 14, when cardiogenesis is essentially complete. At PC 8.0 and older, A1-adenosine receptor (A1AR) activation significantly decreased heart rates. Adrenergic stimulation caused modest increases in heart rates (145–155% of baseline) beginning at PC 9.0. Muscarinic activation decreased heart rates only after PC 13. When receptor gene expression was examined, A1ARs and β1ARs were expressed in isolated hearts as early as PC 9.0, and β2ARs and m2-muscarinic receptor genes were expressed at PC 11.0. These results identify the adenosinergic system as the earliest and most potent regulator of embryonic cardiac function and show that prenatal responsiveness to catecholamines and acetylcholine develops at later embryonic stages.
Energy intake and fur in summer- and winter-acclimated Siberian hamsters (Phodopus sungorus)
Authors: Kauffman Alexander S. , Cabrera Alessandra , Zucker Irving
Published: December 2017

Few studies have directly addressed the impact of fur on seasonal changes in energy intake. The daily food intake of Siberian hamsters ( Phodopus sungorus) was measured under simulated summer and winter conditions in intact animals and those with varying amounts of pelage removed. Energy intake increased up to 44% above baseline control values for approximately 2–3 wk after complete shaving. Increases in food intake varied with condition and were greater in hamsters housed in short than long day lengths and at low (5°C) than moderate (23°C) ambient temperatures. Removal of 8 cm2of dorsal fur, equivalent to 30% of the total dorsal fur surface, increased food intake, but removal of 4 cm2had no effect. An 8-cm2fur extirpation from the ventral surface did not increase food consumption. Food intake was not influenced differentially by fur removal from above brown adipose tissue hot spots. Fur plays a greater role in energy balance in winter- than summer-acclimated hamsters and conserves energy under a wide range of environmental conditions.
Ascorbate dynamics and oxygen consumption during arousal from hibernation in Arctic ground squirrels
Authors: Tøien Ø. , Drew K. L. , Chao M. L. , Rice M. E.
Published: December 2017

During hibernation in Arctic ground squirrels ( Spermophilus parryii), O2consumption and plasma leukocyte counts decrease by >90%, whereas plasma concentrations of the antioxidant ascorbate increase fourfold. During rewarming, O2consumption increases profoundly and plasma ascorbate and leukocyte counts return to normal. Here we investigated the dynamic interrelationships among these changes. Plasma ascorbate and uric acid (urate) concentrations were determined by HPLC from blood samples collected at ∼15-min intervals via arterial catheter; leukocyte count and hematocrit were also determined. Body temperature, O2consumption, and electromyographic activity were recorded continuously. Ascorbate, urate, and glutathione contents in body and brain samples were determined during hibernation and after arousal. During rewarming, the maximum rate of plasma ascorbate decrease occurred at the time of peak O2consumption and peak plasma urate production. The ascorbate decrease did not correlate with mouth or abdominal temperature; uptake into leukocytes could account for only a small percentage. By contrast, liver and spleen ascorbate levels increased significantly after arousal, which could more than account for ascorbate clearance from plasma. Brain ascorbate levels remained constant. These data suggest that elevated concentrations of ascorbate {[Asc]} in plasma {[Asc]p} provide an antioxidant source that is redistributed to tissues during the metabolic stress that accompanies arousal.
Increased flavor preference and lick activity for sucrose and corn oil in SWR/J vs. AKR/J mice
Authors: Smith Brenda K. , Volaufova Julia , West David B.
Published: December 2017

Nutrient preferences and orosensory responses were characterized in two mouse inbred strains. In two-bottle solution tests (tastant vs. vehicle; ascending concentrations), the effects of strain and chow type (12 or 26% fat) on preference thresholds for sucrose and corn oil were compared in AKR/J and SWR/J mice. SWR/J mice displayed lower preference thresholds and ingested more sucrose than AKR/J mice did. SWR/J mice also showed lower preference thresholds and consumed more corn oil than AKR/J mice did; corn oil preference was suppressed 3.5-fold in AKR/J mice compared with SWR/J mice when fed 26% fat chow. Next, licking was recorded during 30-s access to sucrose or corn oil across a range of concentrations. SWR/J mice licked the tastants more than AKR/J mice did. Analysis of modal interlick intervals during lick training revealed that SWR/J mice licked water faster than AKR/J mice when water deprived, suggesting that motor as well as sensory factors may determine lick responses to tastants in brief-access tests. Finally, in two-bottle tests pitting maximally preferred concentrations of sucrose (8 or 16%) against corn oil (20%), SWR/J mice highly preferred sucrose over corn oil at either sucrose concentration. AKR/J mice preferred corn oil over 8% sucrose but reversed their preference when 16% sucrose was offered. These results support a primary role of flavor in the nutrient preferences of SWR/J mice. In AKR/J mice, the low lick activity for sucrose and corn oil and greater suppression of corn oil preference by the high-fat chow suggest that their preferences depend more on postingestive factors than on flavor.
Muscle sympathetic outflow during horizontal linear acceleration in humans
Authors: Cui Jian , Iwase Satoshi , Mano Tadaaki , Katayama Naomi , Mori Shigeo
Published: December 2017

To elucidate the effects of linear acceleration on muscle sympathetic nerve activity (MSNA) in humans, 16 healthy men were tested in a linear accelerator. Measurements of MSNA, electrocardiogram, blood pressure, and thoracic impedance were undertaken during linear acceleration. Sinusoidal linear acceleration with peak values at ±0.10, ±0.15, and ±0.20 G was applied in anteroposterior (±Gx, n = 10) or lateral (±Gy, n = 6) directions. The total activity and burst rate of MSNA decreased significantly during forward, backward, left, or right linear accelerations. The total activity of MSNA decreased to 50.5 ± 6.9, 52.5 ± 4.4, 71.2 ± 9.6, and 67.6 ± 8.2% from the baselines (100%) during linear accelerations with peak values at ±0.20 G in the four directions, respectively. These results suggest that dynamic stimulation of otolith organs in horizontal directions in humans might inhibit MSNA directly in order to quickly redistribute blood to muscles during postural reflexes induced by passive movement, which supports the concept that the vestibular system contributes to sympathetic regulation in humans.
Transplantation of metanephroi after preservation in vitro
Authors: Rogers Sharon A. , Hammerman Marc R.
Published: December 2017

To determine whether transplanted metanephroi grow, differentiate, and function in hosts after preservation in vitro, we implanted metanephroi from embryonic day 15 ( E15) Sprague-Dawley rat embryos into the omentum of nonimmunosuppressed uninephrectomized Sprague-Dawley (host) rats. Metanephroi were either implanted directly or suspended in ice-cold University of Wisconsin (UW) preservation solution with or without added growth factors for 3 days before implantation. The size and extent of tissue differentiation preimplantation of E15 metanephroi implanted directly were not distinguishable from the size and differentiation of metanephroi preserved for 3 days. In contrast, E16 metanephroi were larger than E15 metanephroi preserved for 3 days. E16 metanephroi or E13 metanephroi grown in organ culture for 3 days contained more differentiated nephron structures than those in E15 metanephroi preserved for 3 days. By 4 wk posttransplantation, metanephroi that had been preserved for 3 days had grown and differentiated such that glomeruli, proximal and distal tubules, and collecting ducts with normal structure had developed. At 12 wk posttransplantation, inulin clearances of preserved metanephroi were comparable to those of metanephroi that had been implanted directly. Addition of growth factors to the UW solution enhanced inulin clearances. Here we show for the first time that functional kidneys develop from metanephroi transplanted from rat embryos to adult rats after as long as 3 days of preservation in vitro.
Altered hormone levels and circadian rhythm of activity in the WKY rat, a putative animal model of depression
Authors: Solberg Leah C. , Olson Susan Losee , Turek Fred W. , Redei Eva
Published: December 2017

The Wistar Kyoto (WKY) rat is hyperreactive to stress and exhibits depressive-like behavior in several standard behavioral tests. Because patients with depressive disorders often exhibit disruptions in the circadian rhythm of activity, as well as altered secretory patterns of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid hormones, we tested the hypothesis that these phenomena occur in the WKY rat. Plasma ACTH and corticosterone levels remained significantly higher after the diurnal peak for several hours in WKY rats relative to Wistar rats. Also, plasma levels of thyroid-stimulating hormone were significantly higher in WKY relative to Wistar rats across the 24-h period, despite normal or slightly higher levels of 3,5,3′-triiodothyronine. In addition, under constant darkness conditions, WKY rats exhibited a shorter free running period and a decreased response to a phase-delaying light pulse compared with Wistar rats. In several ways these results are similar to those seen in other animal models of depression as well as in depressed humans, suggesting that the WKY rat could be used to investigate the genetic basis for these abnormalities.
Aldosterone suppresses expression of an avian colonic sodium-glucose cotransporter
Authors: Laverty Gary , Bjarnadóttir Sesselja , Elbrønd Vibeke S. , Árnason Sighvatur S.
Published: December 2017

Transport in the colon of the domestic fowl switches from sodium-linked hexose and amino acid cotransport on high-salt intake to amiloride-sensitive sodium channel expression on low-salt (LS) diets. The present experiments were designed to investigate the role of aldosterone in suppression of the colonic sodium-glucose luminal cotransporter (SGLT). LS-adapted hens were resalinated with or without simultaneous aldosterone treatment. Changes in the electrophysiological responses and SGLT protein expression levels were examined at 1, 3, and 7 days of treatment. Serum aldosterone levels fell from ∼400 pmol/l in LS-adapted hens to values below the detection limit (<44 pmol/l) after 1 day of resalination. At the same time, glucose-stimulated short circuit current ( I SC) increased from 20.9 ± 8.7 to 56.3 ± 15.5 μA/cm2, whereas amiloride-sensitive I SC decreased from −68.9 ± 12.7 μA/cm2 on LS to +0.6 ± 12.0 μA/cm2. Glucose-stimulated I SC increased further at 3 and 7 days of resalination, whereas amiloride-sensitive I SC remained suppressed. When resalinated birds were simultaneously treated with aldosterone, the LS pattern of high amiloride-sensitive I SC and low glucose-stimulated I SC was maintained. Immunoblotting results from the same tissues demonstrated that SGLT-like protein expression increased following resalination. Aldosterone treatment completely blocked this effect. These results demonstrate that aldosterone suppresses both activity and protein expression of hen colonic SGLT. Resalination either through decreased aldosterone or other factors may be able to activate SGLT activity independently of increases in protein expression.