bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrosyl hemoglobin in blood of normoxic and hypoxic sheep during nitric oxide inhalation
Authors: Takahashi Yuko , Kobayashi Hirosuke , Tanaka Naohiko , Sato Tetsuya , Takizawa Naosada , Tomita Tomoyuki
Published: December 2017

During nitric oxide (NO) inhalation therapy, NO combines with deoxyhemoglobin to form nitrosyl hemoglobin (HbNO). We used electron spin resonance (ESR) spectroscopy to measure HbNO in arterial and mixed venous blood of normoxic and hypoxic sheep during NO inhalation. Our aim was to quantitatively measure HbNO levels in the blood during NO inhalation, because large amounts of HbNO reduce the oxygen capacity of blood, particularly in hypoxia. Another aim was to investigate the transfer of exogenous NO to the α-heme iron of hemoglobin. Thirteen sheep were anesthetized with pentobarbital sodium, and 60 parts per million (ppm) NO were administered for 1 h in the presence of normoxia and hypoxia. Two-way analysis of variance revealed that the HbNO level was dependent on the oxygen level (normoxia vs. hypoxia) and NO inhalation, and there was a significant negative correlation between the HbNO level and arterial O2 saturation ([Formula: see text]). Although the HbNO level increased during NO inhalation in hypoxia, the HbNO level at[Formula: see text] >60% was <11 μmol/l monomer hemoglobin (0.11% of total 10 mmol/l monomer hemoglobin). The peak of the HbNO ESR spectrum in arterial blood is located in almost the same position in mixed venous blood with an asymmetric HbNO signal, indicating that the NO in β-heme HbNO molecules had been transferred to α-heme molecules. The three-line hyperfine structure of HbNO on ESR spectra was distinct in venous blood in hypoxia during NO inhalation, indicating pentacoordinate α-NO heme formation in hypoxic blood. In conclusion, the amount of HbNO during 60 ppm NO inhalation did not considerably reduce the oxygen capacity of the blood even in the presence of hypoxia, and the NO of HbNO was transferred to the α-heme iron of hemoglobin, forming pentacoordinate α-NO heme in mixed venous blood in hypoxia.
Blood pressure and heart rate development in young spontaneously hypertensive rats
Authors: Dickhout Jeffrey G. , Lee Robert M. K. W.
Published: December 2017

The course of hypertension development in young spontaneously hypertensive rats (SHR) was studied by the measurement of changes in systolic blood pressure (BP), body weight, and heart rate (HR) at 2, 3, 4, and 6 wk of age. To achieve this, we compared inbreeding lines of SHR and Wistar-Kyoto rats (WKY) to determine if differences in BP, body weight, or HR were present among inbreeding lines of the same strain or between strains. The effect of these differences on the eventual level of BP was then assessed. We found that BP began to diverge between SHR and WKY at 4 wk of age. Significant differences in systolic BP (24 mmHg) between SHR inbreeding lines at 4 wk of age did not affect the BP at 8 wk (172 vs. 170 mmHg). Pulse pressure was significantly higher in SHR than in WKY at 4 wk of age. HR was elevated in SHR over age-matched WKY at 3 wk of age and positively correlated to the level of BP attained by individual animals at 6 wk ( P = 0.037). Moreover, WKY inbreeding lines showing elevated HR developed higher BP (145 vs. 127 mmHg) at 10–12 and 20 wk of age. The prehypertensive tachycardia in SHR was investigated further and found to result from an increased intrinsic HR. Because HR at 3 wk is a genetic trait that can be partitioned into inbreeding lines, and inbreeding lines most expressive of this trait showed the highest eventual BP, we conclude that prehypertensive tachycardia may be an important first step during hypertension development in SHR. Moreover, early elevations in HR are highly predictive ( r = 0.41) of hypertension occurrence in the animal population studied.
Hemodynamic effects ofl-glutamate in NTS of conscious rats: a possible role of vascular nitrosyl factors
Authors: Colombari Eduardo , Davisson Robin L. , Shaffer Richard A. , Talman William T. , Lewis Stephen J.
Published: December 2017

This study examined peripheral mechanisms responsible for changes in mean arterial blood pressure, heart rate, and renal, mesenteric, and hindquarter vascular resistances produced by microinjections of l-glutamate (l-Glu) into the nucleus tractus solitarii (NTS) of conscious rats. Microinjection ofl-Glu produced an initial pressor response, bradycardia, and vasoconstriction in each vascular bed. Subsequent hindquarter vasodilation was observed. After prazosin was administered, l-Glu produced initial hypotension that was probably due to reduced cardiac output. This hypotension was followed by hindquarter vasodilation. Inhibition of nitric oxide synthesis did not affect the initial hypotension or bradycardia in rats treated with prazosin, but the first microinjection of l-Glu after administration of prazosin and N G-nitro-l-arginine methyl ester (l-NAME) produced significantly greater hindquarter vasodilation than after administration of prazosin alone. Second and third microinjections ofl-Glu produced significantly smaller hindquarter vasodilation. We conclude that 1) hemodynamic effects produced by microinjection of l-Glu into the NTS of conscious rats involves activation of the sympathetic nervous system and 2) release of preformed nitrosyl factors may mediate vasodilation in the hindquarter vascular bed.
Correction of hypovolemic hypotension by centrally administered naloxone in conscious rabbits
Authors: Van Leeuwen Andrew F. , Blake Duncan W. , Ludbrook John
Published: December 2017

Our goal was to test directly whether the vasoconstrictor action of naloxone during hypovolemic hypotension is centrally mediated. In eight chronically instrumented rabbits, progressive central hypovolemia and fall in cardiac output (CO) were produced by gradually inflating a cuff on the thoracic vena cava. Central hypovolemia was then sustained for 8 min by holding CO constant. In the main experiment ( n = 4), each rabbit was studied eight times over 4 experimental days. Saline or naloxone treatment commenced 10 min before progressive hypovolemia (early treatment) or 2 min after the onset of sustained hypovolemia (late treatment), given by intravenous infusion or into the fourth ventricle (V4). With saline treatment, there was spontaneous recovery of systemic vasoconstriction and arterial pressure during sustained hypovolemia. Late treatment with naloxone (4 mg/kg iv; 4–37 μg/kg V4) accelerated and exaggerated these changes. Thus, under conditions of constant CO and central blood volume, the vasodilatation of the decompensatory phase of acute hypovolemia is not sustained, and intravenous naloxone’s vasoconstrictor action is via a brain stem mechanism.
ESPVR of in situ rat left ventricle shows contractility-dependent curvilinearity
Authors: Sato Takayuki , Shishido Toshiaki , Kawada Toru , Miyano Hiroshi , Miyashita Hiroshi , Inagaki Masashi , Sugimachi Masaru , Sunagawa Kenji
Published: December 2017

We developed a miniaturized conductance catheter for in situ rat left ventricular (LV) volumetry. After the validation study of the conductance volumetry in 11 rats, we characterized the end-systolic pressure-volume relationship (ESPVR) in 24 sinoaortic-denervated, vagotomized and urethan-anesthetized rats. Stroke volume (SV) measured with the conductance catheter correlated closely with that measured by electromagnetic flowmetry ( r > 0.95). No significant difference was found between the in situ LV end-diastolic volumes measured by conductance volumetry and postmortem morphometry; a linear regression analysis indicated that the correlation coefficient was 0.934, that the slope was not significantly different from 1, and that the intercept was not significantly different from 0. During cardiac sympathotonic conditions, the ESPVR was curvilinear. The estimated slope of ESPVR (end-systolic elastance, E es) by quadratic curve fitting at end-systolic pressure of 100 mmHg was 2,647 ± 846 mmHg/ml. Bilateral cervical and stellate ganglionectomy depressed contractility and made the ESPVR linear; a quadratic equation did not improve the fit. E es was 946 ± 55 mmHg/ml with the volume-axis ( V 0) intercept of 0.076 ± 0.007 ml. Administration of propranolol (1 mg/kg) further reduced E es (573 ± 61 mmHg/ml, P < 0.001) and increased V 0 slightly (0.091 ± 0.011 ml). We conclude that the conductance catheter method is useful for the assessment of the ESPVR of the in situ rat left ventricle and that the ESPVR displays contractility-dependent curvilinearity.
Pentoxifylline attenuates reperfusion injury in skeletal muscle after partial ischemia
Authors: Kishi Masashi , Tanaka Hiroshi , Seiyama Akitoshi , Takaoka Makoto , Matsuoka Tetsuya , Yoshioka Toshiharu , Sugimoto Hisashi
Published: December 2017

Leukocytes have been shown to contribute to ischemia-reperfusion injury in skeletal muscle. Pentoxifylline (PTXF), a xanthine-derived phosphodiesterase inhibitor, has received recent attention because of its action on leukocytes. To clarify the effects of PTXF in reperfusion injury, we measured the resting transmembrane potential difference ( E m) and evaluated postcapillary venule microcirculation using intravital microscopy in rat skeletal muscle during ischemia and reperfusion. The infrarenal aorta was clamped for 90 min and then reperfused for 60 min. Persistent depolarization of the resting E m was observed in an ischemia-reperfusion (IR) group and was significantly repolarized in a PTXF group during the reperfusion period. The tissue water content was significantly reduced in the PTXF group, although no difference was noted in the tissue lactate content. Flowing erythrocyte velocity and wall shear rate in the PTXF group were significantly higher than in the IR group during the reperfusion period but without significant differences in vessel diameter and hemoglobin oxygenation. Blood flow measured by laser-Doppler flowmeter was also significantly improved in the PTXF group. Furthermore, the adherent leukocyte count was significantly reduced in the PTXF group during this same period. These results indicate that PTXF attenuated reperfusion-associated membrane injury and tissue edema and that PTXF suppressed leukocyte adhesion and improved hindlimb blood flow during the reperfusion period.
Central command, but not muscle reflex, stimulates cutaneous sympathetic efferents of cats
Authors: Hill Janeen M. , Kaufman Marc P.
Published: December 2017

We determined the effects of stimulation of the mesencephalic locomotor region (MLR) and the muscle reflex, each evoked separately, on the discharge of cutaneous sympathetic fibers innervating the hairy skin of decerebrate cats. Electrical stimulation of the MLR was performed while the cats were paralyzed with vecuronium bromide. The muscle reflex was evoked while the cats were not paralyzed by electrical stimulation of the tibial nerve at current intensities that did not activate directly group III and IV muscle afferents. MLR stimulation increased, on average, the discharge of the 23 cutaneous sympathetic fibers tested ( P < 0.05). The muscle reflex, in contrast, had no overall effect on the discharge of 21 sympathetic fibers tested ( P > 0.05). Both maneuvers markedly increased mean arterial pressure and heart rate ( P < 0.05). Prevention of the baroreceptor reflex with the α-adrenergic blocking agent phentolamine did not reveal a stimulatory effect of the muscle reflex on cutaneous sympathetic discharge. We conclude that the MLR is a more important mechanism than is the muscle reflex in controlling sympathetic discharge to hairy skin during dynamic exercise.
Fluorescent microspheres are superior to radioactive microspheres in chronic blood flow measurements
Authors: Van Oosterhout Matthijs F. M. , Prinzen Frits W. , Sakurada S. , Glenny Robb W. , Hales J. Robert S.
Published: December 2017

The accuracy of the fluorescent (FM) and radioactive microsphere (RM) techniques is similar in acute experiments but has not been established in chronic experiments. In the present study various combinations (at least pairs) of FM and/or RM labels were injected simultaneously between 2 mo and 5 min before each animal was killed. Blood flow was determined in many organs. Intramethod mean difference and variation did not change over time for FM but increased significantly for RM (from 1.8 ± 1.4 to 25.6 ± 21.8% and from 4.4 ± 3.2 to 32.4 ± 23.0% at 5 min and 2 mo, respectively). Also the FM-RM intermethod mean difference and variation increased (from −0.5 ± 8.5 to 40.8 ± 23.8% and from 23.6 ± 4.6 to 71.8 ± 34.3%, respectively). After 2 mo, blood flow estimations were 20–50% lower with the various RM, whereas brain and liver blood flow values varied even more between isotopes. Underestimation started within 1 day for51Cr and within 2 wk for141Ce,95Nb, and85Sr. We conclude that FM are superior to RM for blood flow determination in experiments lasting longer than 1 day, presumably because of leaching of isotopes from RM.
Melatonin improves cerebral circulation security margin in rats
Authors: Régrigny Olivier , Delagrange Philippe , Scalbert Elizabeth , Atkinson Jeffrey , Lartaud-Idjouadiene Isabelle
Published: December 2017

Because melatonin is a cerebral vasoconstrictor agent, we tested whether it could shift the lower limit of cerebral blood flow autoregulation to a lower pressure level, by improving the cerebrovascular dilatory reserve, and thus widen the security margin. Cerebral blood flow and cerebrovascular resistance were measured by hydrogen clearance in the frontal cortex of adult male Wistar rats. The cerebrovasodilatory reserve was evaluated from the increase in the cerebral blood flow under hypercapnia. The lower limit of cerebral blood flow autoregulation was evaluated from the fall in cerebral blood flow following hypotensive hemorrhage. Rats received melatonin infusions of 60, 600, or 60,000 ng ⋅ kg−1 ⋅ h−1, a vehicle infusion, or no infusion ( n= 9 rats per group). Melatonin induced concentration-dependent cerebral vasoconstriction (up to 25% of the value for cerebrovascular resistance of the vehicle group). The increase in vasoconstrictor tone was accompanied by an improvement in the vasodilatory response to hypercapnia (+50 to +100% vs. vehicle) and by a shift in the lower limit of cerebral blood flow autoregulation to a lower mean arterial blood pressure level (from 90 to 50 mmHg). Because melatonin had no effect on baseline mean arterial blood pressure, the decrease in the lower limit of cerebral blood flow autoregulation led to an improvement in the cerebrovascular security margin (from 17% in vehicle to 30, 55, and 55% in the low-, medium-, and high-dose melatonin groups, respectively). This improvement in the security margin suggests that melatonin could play an important role in the regulation of cerebral blood flow and may diminish the risk of hypoperfusion-induced cerebral ischemia.
Aldose reductase inhibition improves altered glucose metabolism of isolated diabetic rat hearts
Authors: Trueblood Nathan , Ramasamy Ravichandran
Published: December 2017

Alterations in glucose metabolism have been implicated in the cardiovascular complications of diabetes. Previous work in this laboratory demonstrated that hearts from diabetic animals have an elevated cytosolic redox ratio (NADH/NAD+) and that this redox imbalance is probably due to elevated polyol pathway flux. We therefore hypothesized that 1) the elevated cytosolic redox ratio of diabetic hearts could result in inhibition of glycolytic enzymes sensitive to the redox state, 2) polyol pathway inhibition could restore the abnormal glucose metabolism of diabetic hearts, and 3) the relative incorporation of mixed substrates into hearts from diabetic animals would demonstrate less glycolytic and more fatty acid oxidation. Hearts from diabetic ( BB/W) and nondiabetic control rats were perfused with buffers containing13C-labeled substrates, and the metabolism of these hearts was analyzed using13C NMR spectroscopy. Tissue samples were analyzed for metabolite levels using biochemical assay. Compared with controls, diabetic hearts had glyceraldeyde 3-phosphate levels that were four times greater than nondiabetic hearts and exhibited 91% less 13C labeling of lactate and 92% less 13C labeling of glutamate ( P < 0.03). Aldose reductase inhibition with zopolrestat restored the metabolite labeling of diabetic hearts. Diabetic hearts perfused with a mixture of substrates used 53% more acetate than nondiabetic control hearts ( P < 0.05), and aldose reductase inhibition lowered the acetate utilization of diabetic hearts by 9% ( P < 0.05). These data suggest that glycolytic flux in diabetic hearts is inhibited at glyceraldehyde-3-phosphate dehydrogenase and that inhibition of the polyol pathway with zopolrestat increases glycolytic flux in these hearts. Furthermore, hearts from diabetic animals showed a marked dependence on fatty acids for substrate utilization compared with nondiabetic controls, consistent with inhibition of the pyruvate dehydrogenase complex in diabetic hearts.
One-dimensional, nonlinear determinism characterizes heart rate pattern during paced respiration
Authors: Suder Katrin , Drepper Friedhelm R. , Schiek Michael , Abel Hans-Henning
Published: December 2017

This study focuses on the dynamic pattern of heart rate variability in the frequency range of respiration, the so-called respiratory sinus arrhythmia. Forty experimental time series of heart rate data from four healthy adult volunteers undergoing a paced respiration protocol were used as an empirical basis. For pacing-cycle lengths >8 s, the heartbeat intervals are shown to obey a rule that can be expressed by a one-dimensional circle map (next-angle map). Circle maps are introduced as a new type of model for time series analyses to characterize the nonlinear dynamic pattern underlying the respiratory sinus arrhythmia during voluntary paced respiration. Although these maps are not chaotic, the dynamic pattern shows typical imprints of nonlinearity. By starting from a piecewise linear model, which describes the different circle maps obtained from the empirical time series for various pacing frequencies, time invariant measures can be introduced that characterize the dynamic pattern of heart rate variability during voluntary slow-paced respiration.
Role of central circulatory factors in the fat-free mass-maximal aerobic capacity relation across age
Authors: Hunt Brian E. , Davy Kevin P. , Jones Pamela P. , DeSouza Christopher A. , Van Pelt Rachael E. , Tanaka Hirofumi , Seals Douglas R. ,   (With the Technical Assistance of Cyndi Long and Mary Jo Reiling)
Published: December 2017

Fat-free mass (FFM) (primarily skeletal muscle mass) is related to maximal aerobic capacity among healthy humans across the adult age range. The basis for this physiological association is assumed to be a direct relation between skeletal muscle mass and its capacity to consume oxygen. We tested the alternative hypothesis that FFM exerts its influence on maximal aerobic capacity in part via an association with central circulatory function. To do so, we analyzed data from 103 healthy sedentary adults aged 18–75 yr. FFM was strongly and positively related to maximal oxygen consumption ( r = 0.80, P < 0.001). FFM was also strongly and positively related to supine resting levels of blood volume ( r = 0.79, P < 0.001) and stroke volume ( r = 0.75, P < 0.001). Statistically controlling for the collective influences of blood volume and stroke volume abolished the tight relation between FFM and maximal oxygen consumption ( r = 0.12, not significant). These results indicate that 1) FFM may be an important physiological determinant of blood volume and stroke volume among healthy sedentary adult humans of varying age; and 2) this relation between FFM and central circulatory function appears to represent the primary physiological basis for the strong association between FFM and maximal aerobic capacity in this population. Our findings suggest that sarcopenia (loss of skeletal muscle mass with aging) may contribute to the age-related decline in maximal aerobic capacity primarily via reductions in blood volume and stroke volume rather than a direct effect on the oxygen-consuming potential of muscle per se.
Propagation of a High Explosive Air Shock Wave Through Different Parts of an Animal Body
Authors: Clemedson Carl-Johan , Pettersson Hjalmar
Published: December 2017

Anesthetized rabbits were exposed to high explosive shock waves in a detonation chamber and in a blasting range. A barium titanate crystal pressure transducer inserted into the skull, right thorax cavity, upper part of abdomen and femoral musculature was used for the recording of the pressure pattern of the tissue transmitted blast wave. Relatively homogeneous tissues such as those of the brain, abdomen and thigh musculature were found to modify the incident shock wave only little and are not significantly affected by it. The thoracal structures, especially the lungs on the other hand, due to their elastic and damping properties, cause a marked distortion of the incident wave. Only the main pressure peaks but not the more rapid, smaller pressure oscillations of a complex, multi-peak shock wave are transmitted through the lung. Generally, the peak pressure is but little changed by the passage through a tissue or organ. An exception constitutes the thorax when exposed to a short-lasting pressure peak such as that obtained in the blasting range experiments. In this case the peak pressure was considerably reduced.
Initial Radiation Syndrome in the Adult Chicken
Authors: Stearner S. Phyllis , Sanderson Margaret , Christian Emily J. , Brues Austin M.
Published: December 2017

In the adult rooster the dose-rate dependent early mortality that followed x-irradiation was similar to that reported for young chicks. Although a small drop in blood pressure occurred within 30–60 minutes after exposure, a critical hypotension was not seen during the initial postirradiation period. Both 24-hour survivors and nonsurvivors showed an increase in urate excretion during the first 10–12 hours after irradiation. Apparently, the slight fall in blood pressure that occurred after x-ray exposure was not sufficient to affect renal function directly. In addition, the epithelium of the adult kidney is not as radiosensitive as that of the young chick; histopathologic changes are minimal. Although no serious hypotension was observed during the initial postirradiation period in the adult, there was qualitative clinical evidence of a circulatory insufficiency with pooling of blood in peripheral organs. In irradiated chicks a similar condition is accompanied by severe hypotension. However, results of experiments on hemorrhagic shock indicate that the adult can compensate for much greater loss of circulating volume without a decrease in blood pressure than can the young chick.
Mechanism of Erythrocyte Destruction in the Burned Rat
Authors: Davis A. K. , Alpen E. L.
Published: December 2017

The rate of disappearance of Fe59-tagged erythrocytes made by burned and control rats has been measured in both normal and in rats with a 25% body area burn. The erythrocytes made by a burned rat have a mean survival time of 9 days when injected into burned rats. The same cells injected into normal rats have a mean survival time of 42 days. When erythrocytes made by a normal rat were injected into a burned rat the mean survival time was 18 days compared with 40 days when the same cells were injected into unburned controls. These data indicate an increased rate of red cell destruction in the burned rat. As the erythrocytes made by a burned rat do not display an abnormally short survival time in the normal rat and since an increased rate of destruction of erythrocytes is observed when cells from either normal or burned rats are injected into burned rats, it appears that the process of red cell destruction is an abnormality initiated by the burn.
Effect of Potassium Depletion Upon Vascular Reactivity of the Rat's Mesoappendix
Authors: Freed S. Charles , Rosenman Ray H.
Published: December 2017

The depressor effect of potassium deprivation is not associated with a reduction in response to the mesoappendix arterioles to the topical application of epinephrine. Results are in contrast to a lessened blood pressure response of potassium-deficient rats to intravenous pressor agents observed in previous experiments. On the other hand, cortisone administered to potassium-deficient rats restores the lowered blood pressure to normal levels but does not restore the pressor response to intravenous pressor substances. Yet cortisone treated potassium-deficient rats demonstrate a marked increase in response to topical epinephrine on the peripheral vasculature. It is concluded that the response of the mesoappendix vasculature to topical epinephrine cannot be used to explore the mechanism by which potassium restriction lowers blood pressure.
Initial Phase of Ventricular Systole: Asynchronous Contraction
Authors: Rushmer Robert F.
Published: December 2017

The initial phase of ventricular systole has been termed the phase of isometric contraction because all the cardiac valves are closed while the pressure is rapidly elevated. Cyclic changes in the dimensions of the left ventricle, recorded by gauges applied directly to the ventricular walls have consistently exhibited an abrupt expansion of the internal diameter, external circumference and external length of the chamber at the onset of systole. Apparently the longitudinal axis of the chamber is abruptly shortened by early contraction of papillary muscles and trabeculae carnae. The lateral walls bulge outward so that the chamber assumes a more spherical configuration as the internal pressure rises. It is doubtful that any of the myocardial fibers actually contract without a change in length, and the term "isometric contraction" is not appropriate for this phase. The initial stage of ventricular systole is actually a period of asynchronous contraction or sphericalization.
Biological Effects of Methionine Sulfoximine II. Comparative Sulfur Metabolism Studies in Rats and Rabbits
Authors: Gershoff Stanley N.
Published: December 2017

To obtain information concerning methionine sulfoximine-induced convulsions, comparative sulfur metabolism studies of rats and rabbits have been made. Most rat tissues studied contained more sulfur than those of rabbits. Although rabbits excrete the same amount of sulfur as rats per unit body weight, they were found to excrete four times as much of administered methionine. When methionine sulfoximine was injected, extremely small quantities of methionine sulfoximine sulfur were deposited in the brains and spinal cords of rats and rabbits, even though the injections induced convulsions in the rabbits. Methionine sulfoximine inhibited the incorporation of methionine in the tissues of fed animals but not fasted ones. Fasting was also found to partially protect rabbits against methionine sulfoximine toxicity. The possible production of an unknown convulsant by animals in the presence of methionine sulfoximine has been suggested.
Neural Structures Involved in the Genesis of ‘Preoptic Pulmonary Edema,’ Gastric Erosions and Behavior Changes
Authors: Maire Frederick W. , Patton Harry D.
Published: December 2017

Lung edema resulting from preoptic lesions in rats, previously described by Gamble and Patton, was further studied. Mid-line lesions dorsal to the chiasm cause lung edema more consistently than the lateral preoptic lesions described by Gamble and Patton. Vagotomy does not prevent development of lung edema following preoptic lesions. Cervical spinal transection, however, completely prevents development of preoptic lung edema. The evidence suggests that edemagenic impulses traverse the sympathetic outflow, but their effector organs are unknown. Hypothalamic transections dorsal to the chiasm cause lung edema and increased running. Similar transections 1–3 mm caudal to the chiasm are ineffective. Indeed, mid-line lesions in the caudal hypothalamus prevent development of lung edema and hyperactivity when preoptic lesions are inflicted. The evidence suggests that ‘preoptic pulmonary edema’ is a release phenomenon, and that the edemagenic impulses arise from postchiasmatic hypothalamic structures which are normally held in abeyance by the preoptic region. Hemorrhagic gastric erosions were sometimes observed in animals autopsied after preoptic lesions. Neither spinal transection nor caudal hypothalamic lesions diminish the incidence of gastric lesions. Vagotomy, however, prevents development of gastric lesions following preoptic lesions.
Transfer of Electrolytes Across the Urinary Bladder in the Dog
Authors: Hlad Charles J. , Nelson Robert , Holmes J. H.
Published: December 2017

The transfer of certain electrolytes (Na22, Cl36, K42 and P32O4) from the isolated urinary bladder to the plasma compartment was studied in the dog. The rate of transfer was shown to be a function of the ph of the bladder contents over a range of 5 through 8. It was also shown that the rate of transfer was decreased by addition of common ion. Na22 and Cl36 showed greater rates of transfer than did P32O4 and K42. However, ph influences held true for all isotopes. No active mechanism of transfer could be demonstrated and it was concluded that ion exchange was the probable explanation for the transfer process.
Comparison of Fat Emulsion Clearing Activities of Postheparin Plasma and Pancreatic Lipase
Authors: Hollett Charlotte , Meng H. C.
Published: December 2017

Work has been carried out to compare the properties of the lipemia clearing factor of postheparin plasma and pancreatic lipase. It was found that both postheparin plasma and pancreatic lipase exhibited lipolytic activity and were capable of clearing the turbidity of neutral fat emulsion. Intravenous administration of pancreatic lipase was able to clear alimentary lipemia and postlipase plasma was also capable of clearing the turbidity of neutral fat emulsion in vitro. However, the results indicated that the lipemia clearing factor of postheparin plasma was not identical with pancreatic lipase or serum lipase of pancreatic origin. No appreciable change in plasma lipase was observed following intravenous administration of heparin. It is suggested that the lipemia clearing factor of postheparin plasma might be a specific esterase which is capable of splitting the ester bonds of neutral fat of long chain fatty acids.
Arthrokinetic Reflex of the Knee
Authors: Cohen Leonard A. , Cohen Manfred L.
Published: December 2017

The knee joint of decerebrate cats was rotated through a full range of flexion-extension movements. The tensions of quadriceps femoris muscle and semitendinosus muscle were recorded and the responses of these muscles to joint movement were studied. The medial and posterior articular nerves were later sectioned and control records were taken. Flexion of the knee decreased the tension of quadriceps femoris but increased that of semitendinosus. Re-extension of the knee restored both tensions to their resting values. Data were obtained which showed that these responses were reflex in nature. Since the knee joint reflex is basically a slow adapting movement reflex, the name ‘arthrokinetic reflex’ seems appropriate. The activity of the arthrokinetic reflex indicates that its general function is to coordinate knee movement with other nervous activity in thigh muscles. In addition to this, the arthrokinetic reflex of the knee appears to have specific orientation toward dealing with the powerful stretch reflex of the quadriceps femoris muscle.
Autoxidation of Normal Rabbit Marrow Fat in Acetate Buffer
Authors: Evans J. D.
Published: December 2017

When acetate buffer at ph 5.0 was added to normal rabbit marrow in vitro there was a large oxygen uptake attributable to autoxidation of endogenous polyunsaturated fatty acids. Under the experimental conditions the rate of autoxidation was essentially proportional to the quantity of total polyunsaturated fatty acids initially present. Oxygen uptake was measured by the conventional Warburg method whereas polyethenoid acids were determined spectrophotometrically.
Vascular Responses to Adrenaline in the Rat Mesocecum After Intravenous Ferrous Sulfate, Ethylenediamine Tetra-Acetate and Beta1-Globulin
Authors: Crismon J. M. , Dryer Ruth L.
Published: December 2017

Vascular responses to adrenaline were tested by topical application of dilute solutions of the drug to the exposed mesocecum of rats anesthetized with urethane or pentobarbital. Intravenous injections of iron as FeSO4 or iron-saturated beta1-globulin raised the adrenaline threshold. Vasodepression was produced by doses ranging from 45.5–364 µg of Fe/kg in adrenodemedullated rats and from 91–748 µg/kg in unoperated rats. Adrenodemedullated rats developed respiratory embarrassment following injection of 300–400 µg of Fe/kg. Iron-binding agents including the Na or Ca salts of ethylenediamine tetra-acetic acid (EDTA) and unsaturated beta1-globulin given intravenously to test rats lowered the adrenaline threshold. Partial saturation of EDTA with Fe in the proportions of 4 m of EDTA to 1 of Fe produced a ‘neutral’ solution; intravenous injection of this complex produced changes in adrenaline threshold similar to those found after injection of similar volumes of water. Doses of EDTA-Ca or EDTA-Na2, given in the same amount as those that were ‘neutral’ in the presence of Fe, lowered the adrenaline threshold, and doses of FeSO4, containing the same amount of Fe present in the ‘neutral’ EDTA complex, raised the adrenaline threshold. Plasma iron levels were found to be elevated 1 hour after injection of Fe as the beta1-globulin complex but not after similar doses of Fe as the sulfate in Ringer's solution. It is suggested that the changes in adrenaline threshold produced by manipulating the availability of Fe in vivo may reflect altered rates of adrenaline inactivation.
Sodium, Potassium and Nitrogen Balances in Chronic Nephrectomized Dogs
Authors: Houck C. Riley
Published: December 2017

Twelve bilaterally nephrectomized dogs on a low-salt, 54 cal/kg/day diet were maintained for periods up to 3 weeks by intermittent peritoneal dialysis. This procedure maintained the animals in normal sodium balance but provided both a negative potassium and nitrogen balance. The over-all loss of potassium occurred even though the dialysate potassium concentration was varied from 2.8–3.7 mEq/l. It is believed that the negative K and N balances are brought about by loss of plasma protein and some erythrocytes into the peritoneal dialysate. The data indicate that K and N are not lost from the body in the same ratio that they occur in tissues. Renoprival hypertension developes despite failure of the body to retain sodium and despite loss of both potassium and nitrogen from the body.
Sympathomimetic Action of Xanthine Diuretics in the Alligator
Authors: Hernandez Thomas , Coulson Roland A.
Published: December 2017

The injection of caffeine, theobromine, theophylline and Mictine in doses of 25–250 mg/kg produced effects almost indistinguishable from those of epinephrine in doses of 1 mg/kg. The diuretic effects and the pattern of electrolyte excretion in the urine following the injection of the xanthines and Mictine were qualitatively similar to those observed following epinephrine. The xanthines also produced glycogenolysis. Hyperglycemia, increased blood and urine lactic acid, and glycosuria occurred in all experimentals. The xanthine diuretics and Mictine increased neuromuscular irritability. Pupillary constriction occurred following the injection of the xanthines, Mictine, and epinephrine. L-epinephrine and l-norepinephrine resembled epinephrine, U.S.P., in their effects on the alligator. Xanthine in doses of 250 mg/kg was inactive.
Physiology of Spinal Cord, Nerve Root and Peripheral Nerve Compression
Authors: Gelfan Samuel , Tarlov I. M.
Published: December 2017

The reversible conduction block produced by maintained mechanical pressure around small segments of spinal cord, nerve root or peripheral nerve (dog) is due to mechanical deformation of the neuronal tissue and not to lack of O2. The compressed segment, although ischemic, is not anoxic; O2 from adjacent nonischemic tissue reaches it, presumably by diffusion. The entire pattern of modification of neuronal responses by compression and the postdecompression recovery pattern are distinctly different from the patterns observed during anoxia and recovery from the latter, indicating the difference in mechanisms by which mechanical deformation and O2 lack block conduction. The largest fibers in dorsal columns, roots and peripheral nerves are most susceptible to pressure and the smallest ones are relatively most resistant. Secondary neurons are less vulnerable than the primary afferent ones to light and moderate, but suprasystolic, circumferential spinal cord pressure. All components of the composite spinal cord potential are blocked at about the same time by larger compressive forces. Anoxia, on the other hand, always inactivates secondary neurons before dorsal column fibers and blocks smaller A fibers in peripheral nerves before the larger ones. The latency for complete blocking in each neuronal structure is specific and irreducible in the case of anoxia, whereas in compression it varies over a wide range, depending upon the magnitude of the compressive force.
Galactose Metabolism by the Isolated Rat Diaphragm
Authors: Nakada Henry I. , Wick Arne N.
Published: December 2017

Insulin sensitive uptake of galactose by the isolated rat diaphragm has been confirmed. Substrate competition studies using radiocarbon-labeled sugars indicate that galactose has no effect on either the uptake or oxidation of glucose. Glucose lowers galactose uptake slightly and reduces the oxidation of galactose by 25%. Glucose drastically depresses the oxidation and uptake of fructose, while galactose has a negligible effect on fructose. The distribution of C14 in the diaphragm from glucose and galactose was compared. Glucose-C14 activity was found in the metabolic products such as glycogen, CO2, organic phosphates and other products. Most of the radioactive galactose was found in the free form. The small amounts of radioactivity found in the respired CO2, glycogen and organic phosphates do indicate that galactose can be metabolized by the muscle cells.
Postextrasystolic Potentiation of Contraction in Cardiac Muscle
Authors: Hoffman Brian F. , Bindler Elliot , Suckling E. E.
Published: December 2017

The phenomenon of postextrasystolic potentiation of contraction has been studied in papillary muscles isolated from the right ventricle of dog and cat hearts. Isometric tension has been recorded by means of an electronic transducer (RCA #5734) and electrical activity of single fibers by means of an intracellular microelectrode. The degree of potentiation of contraction resulting from a single extrasystole is directly related to the degree of prematurity of this beat. Evidence has been obtained which indicates that the potentiation is maximally effective immediately after the extrasystole and decays at a progressively slower rate during the course of seven to ten beats. The appearance of postextrasystolic potentiation is not dependent upon the changes in frequency of contraction, diastolic interval or presystolic tension which result from the premature contraction. Studies of the transmembrane potentials of single fibers reveal no change in amplitude and little change in configuration of the action potentials associated with potentiated beats. Studies of the resting transmembrane potential and the effects of changes in extracellular concentrations of K and Ca fail to support the concept that potentiation is related solely to changes in the fiber K content. It is concluded that postextrasystolic potentiation results from mechanisms which remain unknown.
Effects of Raised Venous Pressure in the Circulation of the Isolated Perfused Rabbit Ear
Authors: Burton Alan C. , Rosenberg Edith
Published: December 2017

Simultaneous outflow and inflow rates with a constant driving pressure but varying hydrostatic (venous outflow) pressure were measured in 37 isolated ears perfused with Ringer-Locke solution. Flow increased as the hydrostatic pressure was raised (due to passive distension of the vessels) but in six cases there was a decrease in both inflow and outflow at the highest hydrostatic pressures. As hydrostatic pressure was raised outflow fell below inflow, indicating increased capillary filtration, and this complicated the interpretation. It was concluded that in less than half the cases there may have been a ‘veno-vasomotor reflex’ to raised venous pressure. Evidence of the reflex was definite in six (15%) of the cases. The results cannot distinguish between a ‘reflex’ or a possible ‘myogenic effect,’ but do show that it can occur without central nervous connections.
Local Character of the Veno-Vasomotor Reflex
Authors: Rosenberg Edith
Published: December 2017

Critical closing pressures were measured as an index of vasomotor tone in the legs of eight rabbits. In seven of these increases in the venous pressure led to definite and consistent increases in critical closing pressure. In all seven preparations the response persisted when all nervous connections to the rest of the animal were destroyed. This increase in vasomotor tone in response to increased venous pressure is probably due to a local veno-vasomotor reflex.
Development of Acute Pulmonary Edema and Death in Dogs With Aortic Insufficiency Following Renal Artery Constriction
Authors: Hawthorne Edward W. , Brownlee Gwendolyn V. , Jason Robert S.
Published: December 2017

A standardized type of experimental aortic insufficiency was produced in dogs by partial removal of the aortic ‘noncoronary’ valve. A transventricular approach was used to perform the valvulectomies. All dogs with this type of aortic insufficiency, when subjected to renal artery constriction died in 2 days on the average with acute massive pulmonary edema and congestion.
Hypothermia in Hemorrhagic Shock
Authors: Friedman E. W. , Davidoff D. , Fine J.
Published: December 2017

Precooling to 28°C alters the course of hemorrhagic shock in the dog by prolonging the period of tolerance to severe hypotension, and by prolonging the survival time after transfusion from an average of several hours to an average of 30 hours. Precooling does not prevent death. But if an antibiotic is given at the time of transfusion all precooled dogs recover, whereas normothermic dogs given an antibiotic at the time of transfusion do not recover. Precooling protects the dog in hemorrhagic shock by sustaining the antibacterial defense mechanisms, which disintegrate rapidly in the normothermic dog. The protective effects of cooling is not secured if it is applied after the induction of hemorrhagic shock. The effects of hypothermia upon the cardiovascular dynamics are described and their significance discussed.
Electric Responses of the Guinea Pig Ear to High Audio Frequencies
Authors: Pestalozza G. , Davis H.
Published: December 2017

Cochlear microphonic (CM), action potentials (AP), and summating potential (SP) were recorded from the round windows of anesthetized guinea pigs in response to tone bursts that had nearly linear rise and fall of 1.0 msec. each. Frequencies from 8 kc upward were used. CM, AP and SP were all identified up to 48 kc. Here the thresholds for all three responses were nearly identical, but at 12 kc the threshold for SP was higher and for AP much lower than for CM. SP was prominent at high frequencies, and at high intensities its voltage often exceeded that of either AP or CM. The latency from CM to the foot of AP diminishes with increase of intensity and also with increase of frequency. At threshold at 8 kc it was 2.3 msec. and at 30 kc it was 1.4 msec. At all frequencies it approached 1.0 msec. asymptotically as the intensity was increased. The minimal duration needed for maximum AP (measured for a given ratio of stimulus intensity to the usual threshold intensity) was shorter with greater intensity ratios but was independent of frequency.
Kidney Function in the Adult Rat
Authors: Jacobs Julian , Brown J. H. U.
Published: December 2017

Endogenous creatinine clearance of the adult rat has been determined to be 0.556 ml/min/100 gm B. W. This value must be increased about 25% in order to obtain ‘true’ creatinine clearances. Large doses of atropine or hexamethonium decreased the creatinine, sodium and potassium clearances. The clearance of sodium was decreased to a greater extent than was the creatinine or potassium clearance. The urinary Na/K ratio was also decreased in the presence of both drugs.
Sexual Difference in the Survival Time of Rats Exposed to a Low Ambient Temperature
Authors: Zarrow M. X. , Denison M. E.
Published: December 2017

Mature and immature rats of both sexes were exposed to an ambient temperature of 2 ± 2°C. A marked sexual dimorphism in survival time during exposure to cold first appeared in the rats at the age of 60 days and comparable results were obtained with rats at 120 days of age. In both instances the females survived for a much longer period in the cold than the male. Castration had no effect in the female but increased survival time in the male. Pretreatment with daily doses of 0.1 µg of estradiol had no effect while testosterone propionate at dosages of 1 and 5 mg decreased survival time.
In Vivo Visualization of Intracardiac Structures With Gaseous Carbon Dioxide
Authors: Oppenheimer M. J. , Durant T. M. , Stauffer H. M. , Stewart G. H. , Lynch P. R. , Barrera Frank
Published: December 2017

Carbon dioxide gas was injected a) intravenously, b) into the left heart, c) into the peripheral end of the carotid artery. Resulting cardiovascular and respiratory changes were observed by cinefluorography and by measurements of pressure pulses in various locations. Blood and respiratory gas changes were also observed. All changes were minimal (seconds duration) when the gas was introduced on the right or left side of the circulation. Injection into the peripheral carotid produced no untoward effects. The gas gave good visualization of valves and great vessels. Body position was not an important factor in mortality and morbidity when carbon dioxide was the gas used for contrast visualization by a cinefluorography x-ray technique. Carbon dioxide is a safe contrast medium to use for in vivo study of intracardiac structures. The gas has been used successfully by intravenous injection in human cases.
Excretion of Titratable Acid During Acute Respiratory Disturbances of Acid-Base Balance
Authors: Fuller George R. , MacLeod Martha B.
Published: December 2017

In acute experiments on anesthetized dogs, renal excretion of titratable acid was measured during maintenance of high levels of urinary buffer excretion. Acute respiratory acidosis was induced with 12% CO2 and acute respiratory alkalosis by hyperventilation with a respiration pump. The excretion of titratable acid increased during respiratory acidosis and decreased during respiratory alkalosis. Measurements during recovery periods revealed that the effects of respiratory acidosis were rapidly reversible, while respiratory alkalosis produced a lasting depression of the tubular capacity to secrete hydrogen ions. Ammonia excretion showed only small and irregular changes, although it usually increased in respiratory acidosis and decreased during respiratory alkalosis. The results are interpreted in terms of total hydrogen ion secretion by the renal tubules, and it is concluded that respiratory acidosis and alkalosis exert their renal effects by influencing the availability of carbonic acid, and therefore of hydrogen ions, inside the tubular cells.