bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light Sensitivity of the Compound Eye of a Moth (Manduca Sexta) Reared on a Retinol Deficient Diet
Authors: Boëthius Jörgen , Carlson StanleyD. , Hoglund Gunnar , Struwe Goran 
Published: December 2008

AbstractBoëthius, J., S. D. Carlson, G. Hoglundand G. Struwe. Light sensitivity of the compound eye of a moth (Manduca sexta) reared on a retinol deficient diet. Acta physiol. scand. 1972. 84. 289–294.The photoreceptor response was recorded in the compound eye of a moth (Manduca sexta) reared on a retinol (vitamin‐'A) deficient diet. The configuration, amplitude and spectral sensitivity of the receptor potential was similar to that found for normal eyes. The retinol deficient eyes are structurally deranged. The present results therefore indicate that structurally deranged photoreceptors response generate normal receptor potentials.
Circulatory Control via Vagal Afferents
Authors: Castenfors Jan , Sjöstrand Torgny 
Published: December 2008

AbstractCastenfors, J. and T. Sjöstrand. Cirulatory control via vagal afferents. I. Adjustment of heart rate to variations of blood volume in the rat. Acta physiol. scand. 1972. 84. 347–354.On withdrawal of 20–35 % of the blood volume the heart rate may increase, decrease or remain unchanged. The effect has been found to be dependent on animal strain, anesthesia and the autonomic balance. In Sprague‐Daley rats a lowering of the heart rate has been practically constantly observed, sometimes after an initial rise. Bilateral vagotomy eliminates the reduction of heart rate but does not obviously influence the rise. Atropine inhibits the bradycardia largely, and propranolol the tachycardia. On administration of both atropine and propranolol, both the lowering and the rise of heart rate are entirely eliminated. Ligation of the common, external and internal carotid arteries eliminates the bradycardia. Bilateral exclusion of afferents via the communicating branch between the superior and inferior laryngeal nerves usually eliminates the bradycardia.It is presumed that in the rat the heart rate response to hemorrhage is determined by antagonistically acting receptor mechanisms which affect the autonomic tone on the heart, one in a vagotonic and the other in a sympathicotonic direction. The afferents mediating the bradycardia run entirely or for the most part via the recurrent nerve and the laryngeal com‐municans to the cranial part of the cervical vagus.
Gas Permeability of the Alveolo‐pleural Wall in the Mouse Lung
Authors: Andersen Birgit , Madsen Joop 
Published: December 2008

AbstractAndersen, B. and J. Madsen. Gas permeability of the alveolo‐pleural wall in the mouse lung. Acta physiol. scand. 1972. 84. 382–395.Transpulmonary pressure was recorded in isolated mouse lungs during and after step increases in volume. The concomitant sudden increase in transpulmonary pressure was immediately followed by a sharp pressure fall, indicative of stress relaxation. This fall passed into a less pronounced, continuing decline, which appeared to decrease monoexponentially with time. Time constants for this monoexponential pressure fall scattered between 0.005 and 0.017 min˜2 with a tendency to highest values in small animals. In similar experiments, where the lungs were filled and surrounded with N2, time constants were found of the same order of magnitude. In these experiments diffusion capacities for N2 between 0.1 and 0.2 μ min‐1 cm H2O_1 were found. The volumes of gas disappearing from the lungs per unit time and pressure were slightly larger, when the experiments were conducted in air than when done in N2. This difference is probably due mainly to oxygen consumption by surviving lung tissue. Xe passed the alveolo‐pleural wall at a rate 3 times that of N2, while O2 passed the wall at a rate twice that of N2. These figures are consistent with gas diffusion through the intact lung wall.
Effect of Cooling on Synaptic Transmission through the Cuneate Nucleus
Authors: Andersen P. , Gjerstad L. , Pasztor E. 
Published: December 2008

AbstractThe synaptic transmission through the cuneate nucleus was studied during local cooling of the dorsal column region. Field potentials, recorded from the surface as well as inside the nucleus, were greatly increased during moderate cooling (to 30–25o C) but diminished rapidly if the cuneate temperature fell below about 20o C. The increase was most evident for the afferent fibre volley potentials, but large changes of synaptic potentials (N‐wave) were regularly seen as well. The increase (up to several hundred per cent) was partly rate‐dependent since fast cooling gave larger increases than slower cooling did. In spite of the greatly increased N‐wave, the transmission through the nucleus was always reduced. This was tested in various ways: measurement of the latency and probability of firing of single units, “killed end”–recording from lemniscal fibres as a measure of number of discharging cuneate neurones, and measurement of the size of thalamic and cortical field potential produced by impulses relayed through the cuneate nucleus. The reduced transmission was most likely due to a greatly increased synaptic delay, with slowing of conduction along the terminal branches of the afferent fibres as a contributing factor. On severe cooling blocking of conduction in these branches occurred. During moderate cooling the probability of firing of most relay cells remained strikingly high.
Effects of Cooling on Inhibitory Processes in the Cuneate Nucleus
Authors: Andersen Per , Gjerstad Leif , Pasztor Emil 
Published: December 2008

AbstractInhibitory mechanisms in the dorsal column nuclei have been studied during local cooling. The inhibition of transmission of a cutaneous volley across the cuneate nucleus caused by a preceding volley to the same or a neighbouring cutaneous nerve was prolonged and slightly increased by a moderate (25–30o C) reduction of the cuneate temperature. The excitability of presynaptic fibres and of the postsynaptic cell membrane both decreased progressively with decreasing temperature. Presynaptic depolarization increased during moderate cooling (25–30o C) but disappeared when the temperature was reduced to about 20o C.One type of interneurone in the cuneate nucleus showed a progressive disruption of the normal pattern of firing with a gradual increase in the initial latency. An other type showed an increase of the rate and duration of the discharges to a single afferent volley on cooling. The latter type was susceptible to stimulation at 10 per s or higher. The behaviour of the latter interneurones matched the increased and prolonged presynaptic depolarization. These cells may be interneurones in a presynaptic inhibitory pathway. The prolonged and moderately increased inhibition caused by local cooling is probably due to activation of such cells causing increased presynaptic depolarization.
Cholinesterase Activity in Rough and Smooth Brain Microsomal Membranes
Authors: Härkönen Matti , Helve Heikki , Teräväinen Heikki 
Published: December 2008

AbstractRat brain cortex was homogenized in 0.25 M or 0.32 M sucrose and sedimented at 10,000 Xg for 20 min. The supernatant was further separated into two subtractions by density gradient centrifugation in Cs+‐containing sucrose. Electron microscopy, RNA/protein and phospholipid/ protein indices showed that one of the subfractions was similar to the rough‐surfaced (R) and the other to the smooth‐surfaced (S) microsomal fractions separated from liver tissue by Dallner (1963). Cholinesterase (ChE) activity was studied by titration. Only 8–13 % of the total ChE activity was recovered in the 10,000 × g supernatant and about 3–6 % in the subfractions. Both the R and S microsomal subfractions displayed ChE activity; however, the S sub‐fraction had about three times as much activity per mg protein as the R subfraction. Activity due to nonspecific cholinesterase was 13 % of the total ChE activity in the R fraction and 7 % in the S fraction when the homogenate was prepared by homogenization with a clearance of 250 urn at 840 rpm. More vigorous homogenization increased the activities. Histochemical staining for AChE and ns. ChE activities revealed reaction product adjacent to both R and S vesicles.
The Effects of “Immunosympathectomy” on Blood Pressure and Vascular “Reactivity” in Normal and Spontaneously Hypertensive Rats
Authors: Folkow Björn , Hallback Margareta , Lundgren Yen , Weiss Lilian 
Published: December 2008

AbstractNewborn litters of spontaneously hypertensive rats (SHR) and normotensive control rats (NCR) were identically treated with sympathetic nerve growth factor antiserum (Wellcome) which markedly interferes with adrenergic cardiovascular control (Zaimis 1967). Blood pressure, measured intermittently during 8 months, was in treated SHR (SHRis) about 25 % higher than in NCRis, their respective pressures being about 40 % and 25 % lower than those of sham‐treated SHR and NCR.–The hindquarters of one SHRis, or NCRis, were then perfused at constant flow in parallel with those of ordinary NCR. Starting from maximal vasodilatation, resistance increases were induced by graded noradrenaline (NA) infusions, from “threshold” to maximal pressor responses. Compared to NCRis, SHRis showed an increased resistance at maximal dilatation, an increased slope of the NA dose‐response curve and an increased maximal pressor response, while their NA “thresholds” did not differ significantly. Thus, the structurally determined hemodynamic differences between ordinary SHR and NCR (Folkow et al. 1970 b) characterize also SHRis and NCRis, though to a reduced extent. Even when comparing SHRis with ordinary‐ NCR, which exhibited similar “resting” pressures, these differences partly remain, suggesting that the SHR resistance vessels might, for genetic reasons, be more prone to adapt structurally to pressure loads than those of NCR.
Hedgehog Monoamine Oxidase
Authors: Blaschko H. 
Published: December 2008

AbstractHomogenates of the liver, the kidneys and the brain of the hedgehog, Erinaceus europaeus,. have been tested for monoamine oxidase activity. The enzyme was present in all 3 tissues, and the enzyme was found to act on all the substrates known to be oxidised by other mammalian sources of the enzyme. When the rates of oxidation of tyramine and /?‐phenylethylamine were compared, it was found that the relative rate of the latter amine in liver was about 3 times that found for kidneys. In the brain the position seems to be intermediate.
Effect of Physical Activity on the Metabolism of Collagen in Aged Mice
Authors: Heikkinen Eino , Vuori Ilkka 
Published: December 2008

AbstractMale mice, 12–14 months old, were exercised on a treadmill daily for an average of 4 weeks. Another group of mice were kept in small cages, in which their motility was considerably limited. A third group served as controls under normal laboratory conditions. Tritiated proline was injected intraperitoneally into the mice at the end of the experimental period, where upon die turnover of collagen and other proteins was measured and the contents of hexosamine, hydroxyproline, nitrogen, calcium, potassium and sodium were determined in various tissues. Metabolism of collagen was increased by exercise and decreased by physical inactivity especially in Achilles tendons and long bones. The ratio of hydroxyproline to nitrogen was highest in the Achilles tendons of the exercised mice. The content of hexosamine was increased by exercise in the skin and decreased by physical inactivity in long bones. No significant differences in the concentrations of calcium, potassium and sodium ions in long bones and in the heart and skeletal muscles were observed. The results show that the metabolism of connective tissues is influenced by degree of physical activity even in relatively old animals.
Influence of Muscle Length on the Mechanical Parameters of Myocardial Contraction
Authors: Nilsson E. 
Published: December 2008

AbstractStiffness determinations were made on rabbit papillary muscles at different lengths. Both in resting preparations and in muscles contracting at lengths, where resting force was very low compared with active force, the stiffness increased recti‐linearly with force. At any force level, the stiffness of a preparation was greater at rest than during activity.—Force‐velocity curves were determined at different muscle lengths and, when necessary, data for the whole preparation were corrected for the influence of the parallel elasticity in order to derive the force‐velocity curves of the contractile element alone. Vmax and PO of the contractile element (i.e. its shortening velocity at zero load and its maximum force‐producing capacity) determined at peak isometric force were increased approximately in parallel by elongation at short muscle lengths, whereas at lengths near the optimum for active force, Vmax was influenced slightly more than Po by length changes.—The time course of the active state was critically dependent upon muscle length: an increase in length prolonged the time from stimulation to 60% decay of the active state, without significantly altering the time course of its rising phase.
The Effect of Acetazolamide upon the Regulation of the Cerebrospinal Fluid pH in the Rat
Authors: Messeter Kenneth 
Published: December 2008

AbstractThe influence of large doses of acetazolamide upon the regulation of the CSF pH in normocapnia and hypercapnia was studied in non‐nephrectomized and nephrectomized rats. In non‐nephrectomized animals studied over a 24 h period there was a decrease in the CSF HCO‐3 concentration of 10 mEq/kg. Since the CSF acidosis was far in excess of that usually encountered with a comparable degree of plasma acidosis, the results indicate that acetazolamide inhibited a carbonic anhydrase‐dependent transport of H+or HCO‐3 between CSF and plasma. However, when the fall in plasma [HCO‐3] was prevented by means of a bilateral nephrectomy, acetazolamide did not affect the CSF pH under normocapnic conditions, nor did it retard the accumulation of HCO‐3 in the CSF during hypercapnic conditions. The results do not support any of the existing hypotheses which try to explain the regulation of the CSF pH in both respiratory and non‐respiratory acid‐base disturbances in terms of a common mechanism.
Reactive Hyperemia in Subcutaneous Adipose Tissue in Man
Authors: Nielsen Steen Levin , Sejrsen Per 
Published: December 2008

AbstractBlood flow in the subcutaneous tissue on the calf was measured with the local Xenon‐133 washout method after varying periods of ischemia. Reactive hyperemia occurred. Maximal flow, cumulative flow, and excess flow were dependent on the duration of the ischemia. The increase in cumulative flow caused by increment in the duration of the ischemic period was characteristic for each individual and was significantly correlated to the resting blood flow. This probably indicates adipose tissue blood flow to be governed by local metabolic factors, as the tissue only shows a limited auto regulatory response.
Effects of Secretin, Cholecystokinin and Caerulein on Gastric Secretion in Response to Sham Feeding in Dogs
Authors: Sjödin Lars 
Published: December 2008

AbstractSecretin (0.75–3.0 U/kg/h) did not regularly inhibit the acid secretory response to 10 min of sham feeding to a significant degree in 3 dogs with intact antrum. Cholecystokinin (0.75–5.0 U/kg/h) and caerulein (0.06–0.30 μ/kg/h) tended to increase acid output after sham feeding in these dogs. In antrectomized dogs the response to sham feeding was markedly enhanced by cholecystokinin (0.6–2.4 U/kg/h) and caerulein (0.06 μg/kg/h). Pepsin output after sham feeding was increased by secretin (3.0 U/kg/h) and tended to be reduced by cholecystokinin (3.0 U/kg/h) and caerulein (0.30 μg/kg/h). These findings indicate that gastric acid secretion in response to sham feeding is not inhibited by physiological amounts of secretin and in fact increased by cholecystokinin and caerulein. The pepsin output after sham feeding can be enhanced by secretin and possibly depressed by cholecystokinin. The physiological significance of these effects on pepsin secretion remains to be determined.
Influence of Secretin and Cholecystokinin on Canine Gastric Secretion Elicited by Food and by Exogenous Gastrin
Authors: Sjödin Lars 
Published: December 2008

AbstractThe present study showed that in Pavlov pouch dogs gastrin stimulated acid secretion was more markedly inhibited by secretin and cholecystokinin than the secretion elicited by food. The acid secretory response to a test‐meal was only moderately reduced by 3.0 U of secretin/kg/h; the reduction was not statistically significant. In 2 of 3 tested dogs inhibition of the secretion after a test‐meal was more marked when 3.0 U of cholecystokinin (a 10 % pure preparation)/kg/h was administered. However, this dose of cholecystokinin caused some side effects, such as decreased appetite, in the dogs. These doses of cholecystokinin and secretin probably produce unphysiologically high blood levels of the hormones. In spite of the high doses the acid secretory response to a test‐meal was never abolished. This makes it doubtful if these hormones should be regarded as physiologically important inhibitors of gastric acid secretion. Pepsin output after a meal was clearly enhanced by a concomitant infusion of 3.0 U of secretin/kg/h. On the other hand, the same number of units of cholecystokinin markedly inhibited the pepsin output after a meal.
Facilitation and Inhibition of Facial Reflexes in the Cat Induced by Peripheral Stimulation
Authors: Lindquist Christer 
Published: December 2008

AbstractThe effects of conditioning peripheral stimuli on reflexes elicited in m. caninus and m. orbi‐cularis oculi by tap stimulation of the facial skin have been studied in cat. Following a conditioning facial skin tap the reflex transmission was facilitated for some 20 ms and this facilitation was succeeded by a period of reflex depression lasting up to 400 ms. A similar type of interaction was observed when the conditioning stimulus consisted of afferent volleys in the lingual or the hypoglossal nerve. Reflex depression of several hundred ms duration resulted when conditioning volleys were elicited in group II afferents in the radial nerve or in afferents of the saphenous nerve.—I. v. injections of strychnine resulted in considerably diminished inhibitory effects of conditioning facial taps which was taken to indicate that postsynaptic mechanisms are involved in the inhibitory reflex control. The reflex depression induced by activity in radial nerve afferents was not affected by strychnine injections to the same extent. It is suggested that the time course of the facial reflex inhibitions indicates involvement of presynaptic inhibition as well.—In the chloralose‐anesthetized cat the blink reflex was suppressed to a considerable degree when elicited at a frequency of 4/s and was almost abolished at 10/s. This “reflex fatigue” was not changed by decerebration. It is suggested that presynaptic inhibitory mechanisms account for the fatiguability of the blink reflex.
Analysis of Facial Reflex Facilitation and Inhibition by Microelectrode Recording from the Brain Stem
Authors: Lindquist Christer 
Published: December 2008

AbstractThe response in the facial nucleus to stimulation of peripheral facial and trigeminal nerve branches is described. After antidromic invasion the excitability of facial motoneurons was lowered for up to 30 ms before as well as after intravenous injections of strychnine. The depression following antidromic stimuli is thus not caused by postsynaptic inhibition of the Renshaw type but rather by positive afterpotentials in the motoneurons. Synaptic activation by tap stimulation of the face led to increased motoneuron excitability setting in after a latency of 3 ms and lasting for 30 ms. This was followed by a lowered excitability lasting for an additional period of 65 ms. The period of depression was presumed to be due to postsynaptic inhibition of motoneurons. The changes of the excitability of facial motoneurons following synaptic activation explain in part previously observed effects of conditioning afferent stimuli on facial reflexes.‐Responses to electrical stimulation of facial and hypoglossal nerve afferents were recorded from reticular neurons. These neurons responded to single stimuli with a repetitive high‐frequency discharge related to the stimulus strength and could respond to an afferent inflow from large areas of the body and limbs. It is discussed whether these reticular neurons may be interneurons in a system exerting inhibitory control of facial muscle reflexes.
The Effect of Calcium on the Potassium Permeability in the Myelinated Nerve Fibre of Xenopus Laevis
Authors: Brismar Tom , Frankenhaeuser Bernhard 
Published: December 2008

AbstractThe effect of changes in the external calcium concentration (in the range from 0.27 to 109 mM) on the potassium permeability mechanism has been investigated with potential clamp technique. An increment in [Ca] was associated with a positive shift along the potential axis of the curve relating the potassium permeability variable (nm) to the membrane potential. This shift varied between 3 mV per e‐fold change in [Ca] at low concentrations and 10 mV in the range of high [Ca]. Changes in magnesium concentration were associated with a similar shift.
Thermoregulation during Positive and Negative Work at Different Environmental Temperatures
Authors: Nielsen Bodil , Nielsen S. Levin , Petersen F. Bonde 
Published: December 2008

AbstractCardiac output, and thermoregulatory reactions were studied at 20°, 30° and 35° C during positive work (pos I) and negative work (neg) at O2‐uptakes of 0.8 l/min, and also during positive work (pos 11) at an O2‐uptake of 1.7 1/min). i.e. with a total heat production equal to that during the negative work. At equal O2‐uptakes the cardiac output (Q) was the same in pos I and neg. The blood flow in the working muscles, estimated with a 133Xe method, was not measurably different in pos I and neg. The upper limit for thermal equilibrium was reached at lower environmental temperature in negative work. This is most probably explained by the higher skin circulation during negative work. Since the total Q and muscle blood flow is the same in pos I and neg the blood reserve available for heat transport during external heat stress, e.g. in splanchnic organs is presumably reduced in negative work.
Fluid Transfer between Blood and Tissues during Exercise
Authors: Lundvall J. , Mellander S. , Westling H. , White T. 
Published: December 2008

AbstractDuring 6 min exercise on a bicycle ergometer the volume of the leg in normal males increased so as to indicate, after correction for increased regional blood volume, an average trans‐capillary fluid loss into the leg muscles of 19, 31, and 45 ml/kg tissue at light (300 kpm/min), moderate (900 kpm/min), and heavy (1200–1500 kpm/min) work load. The total fluid loss into the active muscle mass was calculated to comprise about 1100 ml during heavy work. Since the concomitant decrease of plasma volume was 600 ml, it follows that some 500 ml of fluid must have entered the circulatory system during the work. The study indicated that this compensatory fluid gain was accomplished by absorption of extravascular fluid from inactive tissues and partly caused by osmosis resulting from work induced arterial hyperosmolality (average increase 22 mOsm/kg H2O). Fluid absorption from inactive tissues was studied in experimental animals during exercise and in resting humans during arterial hyperosmolality produced by intravenous hypertonic infusions. The investigations suggested that at least half of the fluid gain to the circulatory system in heavy exercise could be ascribed to the increased arterial osmolality and the remainder to a reflex decrease of capillary pressure.