bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gastric blood flow in anaesthetized cats
Authors: Harper A. A. , Reed J. D. , Smy J. R. 
Published: December 2014

1. The gastric mucosal blood flow has been measured by the amidopyrine clearance technique in anaesthetized cats. The total gastric blood flow has been (a) measured directly and (b) calculated by the Fick principle from the amidopyrine concentrations in gastric arterial and venous blood and the gastric output of amidopyrine.2. Observations on the recovery of added amidopyrine from arterial and venous blood and plasma, and on the rate of transfer of amidopyrine from corpuscles to plasma, support the underlying assumptions of the amidopyrine method of measuring mucosal blood flow.3. If acid solutions are instilled into the stomach the mucosal blood flow of the non‐secreting stomach may be measured by the amidopyrine technique.4. Total gastric and mucosal blood flow increased linearly with increase in H+ secretion, stimulated by histamine or gastrin. The increase in total flow was entirely due to the increase in mucosal flow.5. The relationship between mucosal blood flow and H+ secretion was the same for histamine and gastrin responses, and was unaffected by maintaining the total flow at a constant level, or by reduction of the circulating blood volume. Increase in blood volume altered the relationship so that there was a greater increment in mucosal blood flow for any increase in H+ secretion.6. It is concluded that valid observations may be made on secretion and blood flow relationships in acute anaesthetized preparations.
The effect of intraventricular injections of noradrenaline, 5‐hydroxytryptamine, acetylcholine and tranylcypromine on the ox (Bos taurus) at different environmental temperatures
Authors: Findlay J. D. , Thompson G. E. 
Published: December 2014

1. Noradrenaline, 5‐hydroxytryptamine (5‐HT), acetylcholine and tranylcypromine were injected or infused into the lateral ventricle of the ox. The effects of these drugs on heart and respiration rates, heat production, rectal, skin and hypothalamic temperatures and skin evaporative loss were measured when the animal was exposed to environmental temperatures ranging from ‐1° C to +30° C.2. Acetylcholine (0·001‐2 mg) had no detectable effect on temperature regulation at 20° C.3. In small doses (0·005‐0·05 mg) 5‐HT had no detectable effect. Larger doses (2‐5 mg) given in a cold environment (‐1° C) also had no effect but the same doses given in warm environments (15‐30° C) caused increases in skin temperatures, skin evaporative loss and respiratory rate, and decreases in rectal and hypothalamic temperatures.4. Infusion of tranylcypromine (0·107 ml./min of a 1 in 50 solution) in a warm environment (20° C) also caused a decrease in rectal temperature after a delay of 1‐1½ hr during which no effects were apparent.5. Noradrenaline (2 mg) had no effect on temperature regulation when injected into animals in a warm environment (30° C). When injected (1 mg) into animals in a cold environment (‐1° C) shivering stopped and heat production and rectal and hypothalamic temperatures were decreased.6. It is concluded that intraventricular 5‐HT and noradrenaline both cause a decrease in body temperature, and it is unlikely that central temperature regulation in the ox is mediated only by these two substances.
The site of action of ‘chlormadinone acetate’ (6‐chloro‐Δ6‐dehydro‐17α‐acetoxyprogesterone) in blocking ovulation in the mated rabbit
Authors: Exley D. , Gellert R. J. , Harris G. W. , Nadler R. D. 
Published: December 2014

1. In a study of the site of action of a steroid in current use for contraceptive purposes (6‐chloro‐Δ6‐dehydro‐17α‐acetoxyprogesterone; ‘chlormadinone acetate’), the ovarian responses [secretion rate of 20α‐hydroxypregn‐4‐en‐3‐one (20 α‐OH), and the occurrence of ovulation] were observed in control oestrous rabbits and in rabbits following mating, injection of luteinizing hormone, and after electrical stimulation of the median eminence.2. Chlormadinone acetate pretreatment (0·5 mg
I.V.) did not lower significantly the secretion of 20 α‐OH in otherwise untreated oestrous rabbits.3. Chlormadinone acetate, given 24 hr before mating, prevented the rise in 20α‐OH that would otherwise have occurred, and also blocked the ovulation response following mating.4. Chlormadinone acetate pretreatment did not prevent the ovarian responses to administration of luteinizing hormone.5. Chlormadinone acetate pretreatment did not prevent the ovarian responses to electrical stimulation of the median eminence of the tuber cinereum of the hypothalamus.6. The conclusion is drawn that the chlormadinone acetate block of the ovarian responses following mating is at a site in the central nervous system located above the median eminence.
Somatic afferent input to posterior thalamic neurones and their axon projection to the cerebral cortex in the cat
Authors: Rowe M. J. , Sessle B. J. 
Published: December 2014

1. A technique of reversible block of synaptic transmission through the dorsal column nuclei and the trigeminal nucleus caudalis (n. caudalis) has been employed to assess the somatic afferent input to individual posterior thalamic neurones in the cat. The axon projection to the cerebral cortex of these neurones has been identified by antidromic activation following cortical stimulation.2. Unitary responses in the nucleus ventralis posterolateralis (VPL) evoked by cutaneous stimulation were abolished or depressed following block of transmission in the dorsal column nuclei. Block in n. caudalis, however, depressed unitary responses in nucleus ventralis posteromedialis (VPM) evoked by facial skin stimulation in less than 10% of cells.3. A more complex source of the somatic input to the posterior nuclear region of the thalamus (PO) was found. It was most commonly noted that PO unitary activity evoked by cutaneous stimulation of the face was unaffected by block of synaptic transmission in n. caudalis. No uniform effect was observed on unitary responses in PO evoked by limb stimulation when transmission in the dorsal column nuclei was blocked.4. Antidromic activation from the cerebral cortex was seen in 69% of ventrobasal neurones. Most cells (66%) had ‘antidromic cortical fields’ restricted to a region consisting of a third to a half of the specific somatic projection areas. In 10% of cells evidence was obtained for discontinuous cortical ‘antidromic fields’ suggesting subcortical bifurcation of the projecting axon.5. An axon projection to the cortex was found in 35% of PO cells, about half of which projected only to specific somatic projection areas. Evidence for subcortical branching of the axon was obtained for seven PO cells.
The distribution of proteins that bind neurohypophysial hormones
Authors: Ginsburg M. , Jayasena K. 
Published: December 2014

1. Protein fractions were prepared from serum and various organs of pigs following the methods used to extract and purify neurophysin from posterior pituitaries.2. Protein fractions extracted from porcine kidney, uterus, mammary gland or serum, which contain antigen reacting with anti‐neurophysin serum, form non‐dialysable complexes with oxytocin and/or lysine vasopressin.3. Protein from uterus or mammary gland bound oxytocin but not lysine vasopressin, while protein extracted from kidney bound lysine vasopressin but not oxytocin: protein from serum bound both hormones.4. Protein fractions prepared in the same way from porcine liver, spleen, skeletal muscle and brain, which do not contain antigen reacting with anti‐neurophysin serum, did not form complexes with neurohypophysial hormone.5. The formation of complexes between the renal or uterine protein fractions and lysine vasopressin or oxytocin is inhibited by the addition of 1·0 × 10−6
M‐CaCl2.6. 1‐Desamino 8‐arginine vasopressin is not bound by neurophysin prepared from porcine posterior pituitaries or the protein from porcine kidneys, while 8‐arginine vasopressin does form non‐dialysable complexes with proteins from both sources.7. A protein fraction extracted from guinea‐pig kidney by similar preparative methods also bound lysine vasopressin and the binding was inhibited by addition of CaCl2.
Circadian rhythms in rat mid‐brain and caudate nucleus biogenic amine levels
Authors: Friedman Alexander H. , Walker Charles A. 
Published: December 2014

1. The circadian rhythms of rectal temperature and biogenic amine levels in mid‐brain and caudate nucleus have been measured in normal and adrenalectomized rats adapted to and maintained under fixed illumination cycle.2. Rectal temperature reaches a peak value between 24.00 hr and 06.00 hr during the dark phase of the illumination cycle at a time when motor activity is maximal. In adrenalectomized rats, the pattern is similar but the peak is significantly lower.3. Highest histamine levels in the caudate nucleus and mid‐brain of normal and adrenalectomized rats are found at the time when body temperature and motor activity is maximal.4. Similarly, caudate nucleus and mid‐brain noradrenaline levels reach their peak during the dark phase of the illumination cycle. These levels are significantly different from those found during the light phase of the illumination cycle. The rise in noradrenaline in the mid‐brain of adrenalectomized rats, however, was not significant.5. Peak 5‐hydroxytryptamine (5‐HT) levels in the caudate nucleus of normal rats and the mid‐brain of adrenalectomized rats were found to be 12 hr out of phase with peak values obtained for other parameters that were measured.6. The significance of these circadian rhythms in relation to states of sleep and wakefulness, general metabolism, and motor activity is discussed.
Effects of water diuresis and osmotic (mannitol) diuresis on urinary solute excretion by the conscious rat
Authors: Atherton J. C. , Hai M. A. , Thomas S. 
Published: December 2014

1. The time course and extent of changes in urinary flow and in the outputs of urea, Na+, K+, and NH4+ over a period of 7½ hr in conscious rats during water and osmotic (mannitol) diuresis were determined, and compared with spontaneous changes in non‐diuretic animals.2. In non‐diuretic rats, a morning rise and subsequent decline in urinary osmolal, sodium, potassium and ammonium outputs occurred, possibly attributable to circadian rhythms.3. Water diuresis was accompanied by (i) a rapid increase in urea excretion during the phase of increasing urine flow, followed by a fall in later periods to values similar to those in non‐diuresis, (ii) a slower increase in sodium output, continuing after the establishment of the constant water load, (iii) unchanged potassium excretion, but slightly increased ammonium outputs.4. Mannitol diuresis was accompanied by (i) a rapid increase in urea outputs which subsequently fell but remained significantly higher, (ii) a steep rise in sodium and potassium outputs to values which remained far higher than those in non‐diuretic and water diuretic animals.5. The changes in mannitol diuresis are considered to result mainly from decreased tubular reabsorption, due to the lowered intraluminal sodium, potassium and urea concentrations and increased intratubular fluid flow. Some of the acute increase in urea excretion may be due to washout of medullary urea into the tubular fluid.6. In water diuresis, some of the changes in solute excretion may similarly result from altered tubular reabsorption, perhaps influenced by suppression of anti‐diuretic hormone (A.D.H.). In addition, the slower changes in sodium output may be related to several consequences of change in body fluid volume.
Quantitative aspects of sensitivity and summation in the cat retina
Authors: Cleland B. G. , Enroth-Cugell Christina 
Published: December 2014

1. Properties of the central response mechanism of on‐centre ganglion cells in the cat retina were studied by recording, from optic tract fibres, responses evoked by stimuli modulated with time in a sinusoidal or square‐wave fashion.2. The shape of averaged square‐wave responses resulting from the central mechanism alone was identified. This shape was identical from one cell to another. Such an identification permits the early recognition of peripheral antagonism.3. Threshold sensitivity for a sinusoidal stimulus was determined for fifty cells along one horizontal and vertical axis, passing through the most sensitive portion of the receptive field. These sensitivity profiles were described in terms of a central segment of constant maximum sensitivity (uniform centre) and sloping outer segments of exponentially decreasing sensitivity (exponential annulus). The dimensions of the uniform centre (horizontal axis × vertical axis) varied from 0·1° × 0·1° to 2·5° × 2·2°, the half width of the exponential annulus ranged from 0·1° to 0·63°.4. Adapting spots of varying diameter were placed concentric with the receptive field and the (unmodulated) luminance, at each diameter, that reduced a small central (sinusoidal) stimulus to threshold, was determined. The resulting area—adaptation curve, (adapting luminance plotted against diameter) showed that within defined limits the state of adaptation is determined by the flux independent of its distribution.5. Sinusoidal stimuli of varying diameter were placed concentric with the receptive field and the threshold luminance at each diameter was determined. Suprathreshold square‐wave stimuli indicated that the central mechanism alone contributed to the response. These area‐sensitivity curves did not show any decrease in sensitivity at larger diameters.6. The shape of the area—sensitivity curve, and hence the extent of the summating area, was found to be independent of the state of adaptation.7. For any one cell the shapes of the area—adaptation and area—sensitivity curves were shown to be identical, indicating that adapting flux and stimulus flux are independent of distribution over the same defined limits.8. The sensitivity of combinations of small disconnected areas of the receptive field was found to be equal to the sum of their individual sensitivities.
The effect of 2,4‐dinitrophenol and related compounds on bile secretion
Authors: Pugh Patricia M. , Stone S. L. 
Published: December 2014

1. 2,4‐dinitrophenol, 2,4‐dinitrophenetole, 2,4‐dinitronaphthol, 4,6‐dinitro‐o‐cresol, and to a lesser extent picric acid, produced an increase in bile flow and a rise in body temperature in the anaesthetized dog. The total biliary bromsulphalein (BSP) excretion in unit time was either slightly reduced, increased or remained at its pre‐injection level.2. Picramic acid, the nitrochlorophenols and 2,4‐dinitrobenzaldehyde caused a moderate increase in bile flow without an effect on the temperature of the animal.3. The three mononitrophenols, the five remaining isomeric dinitrophenols, isopicramic acid, the aminonitrophenols, phenol, 2,4‐dinitroanisole, 2,4‐dinitrobenzoic acid, 2,4‐dinitrobenzene sulphonic acid, 2,4‐dinitroresorcinol and 4‐nitracatechol had little effect on bile secretion or body temperature.4. It thus appears that, in order for a compound of this type to have a pronounced effect on bile secretion, it is necessary to have nitro groups in positions 2 and 4 of the benzene ring, and a free or potential hydroxyl group.
Shivering and non‐shivering thermogenesis during summit metabolism in young lambs
Authors: Alexander G. , Williams D. 
Published: December 2014

1. Summit metabolism of lambs declined steadily from about 3·5 l. O2/kg.hr during the first day of life, to about 2·0 l. O2/kg.hr at 2 months of age.2. The contributions of shivering and non‐shivering thermogenesis to these changes were estimated by three independent methods; non‐shivering thermogenesis was stimulated by catecholamines in a thermoneutral environment, shivering was suppressed by curariform drugs during summit metabolism, and an attempt was made to suppress non‐shivering thermogenesis during summit metabolism by use of the sympatholytic drugs phentolamine and propranolol. Drugs were given by intravenous infusion during measurement of oxygen consumption in a closed circuit respiration chamber.3. ‘Resting’ metabolic rate of lambs during the first day of life was increased two to three‐fold, from 1 l. O2/kg.hr, by either adrenaline or noradrenaline infused at 1‐10 μg/kg.min. The increase declined with increasing age of lamb and was virtually absent by 3 weeks. The response to catecholamines appeared maximal at the dose levels used.4. Muscular paralysis induced by suxamethonium or gallamine reduced summit metabolism by about 2 l. O2/kg.hr in all lambs examined within the first 2 months of life. The residual metabolic rate, and the metabolic response to catecholamines under thermoneutral conditions, declined with age in the same manner, and their magnitudes were similar.5. Summit metabolism in lambs aged up to 2 months was depressed to varying degrees by the sympathetic inhibitors phentolamine, propranolol and hexamethonium. The depression with propranolol was greater, and the decline with age clearer, than with phentolamine. Hexamethonium and phentolamine depressed blood pressure, propranolol decreased heart rate and phentolamine and propranolol each suppressed shivering in some experiments.6. In 1 day‐old lambs estimates of non‐shivering thermogenesis, by the various methods, ranged from 0·8 to 1·4 l. O2/kg.hr (mean 1·1 l. or 31% of summit metabolism), and the estimates of shivering ranged from 1·3 to 1·9 l. O2/kg.hr (mean 1·6 l. or 46% of summit metabolism). However, in lambs 1‐month old, estimates of non‐shivering thermogenesis from sympathetic inhibition (0·6 and 0·8 l. O2/kg.hr) were considerably higher than estimates from muscular paralysis or stimulation by catecholamines (0·2 and 0·1 l. O2/kg.hr). It is suggested that the depression of summit metabolism by the sympathetic inhibitors is not solely due to specific inhibition of non‐shivering thermogenesis, at least in the older lambs.7. The possession of a non‐shivering thermogenic mechanism in addition to shivering is of clear survival value to new‐born lambs.
Vagal control of thermal panting in mammals and birds
Authors: Richards S. A. 
Published: December 2014

1. The role of the vagus nerves during normal respiration and thermal polypnoea was examined in four species of mammals and four species of birds by lung/air sac inflation and cervical vagotomy.2. The Hering—Breuer inflation reflex could be elicited in all of the mammals during both normal respiration and panting; it was present in the fowl and pigeon at normal body temperature only.3. Section of one vagus during hyperthermia reduced respiratory frequency in most animals and increased depth. Bilateral vagotomy had little further effect in the panting rabbit, lamb and pigeon, but abolished rapid respiration in the rat, guinea‐pig, fowl, duck and quail.4. Vagotomized lambs and pigeons started panting in response to increasing body temperature, although the rate attained was slower than in intact animals. Guinea‐pig, rat, fowl and quail did not pant under these conditions.5. Appropriate afferent vagal stimulation in the vagotomized fowl maintained normal respiration or thermal panting.6. It is concluded that panting can, in some mammals and birds, be controlled by central mechanisms alone, while in others it depends on extrinsic stimuli mediated by way of the vagus nerves.
Oxygen consumption in normally grown, small‐for‐dates and large‐for‐dates new‐born infants
Authors: Hill June R. , Robinson D. C. 
Published: December 2014

1. Serial measurements of minimal oxygen consumption (V̇O2) have been obtained from nineteen healthy new‐born infants in order to find out how body weight, gestational age and age after birth affected V̇O2. The first measurement of V̇O2 was done within 12 hr of birth, and further measurements were made at intervals until the baby left hospital.2. The majority of the infants (seventeen) weighed less than 2·5 kg at birth, and were ‘premature’ according to international definition. Gestational age, calculated from the mother's last menstrual period, was corroborated by clinical data and obstetrical history. The babies were divided into four groups according to birth weight and gestational age combined (see Table 1). Babies in the first two groups were the appropriate weight for dates (i.e. normally grown), babies in the other two groups were either small‐for‐dates or large‐for‐dates.3. At birth minimal V̇O2 was closely correlated with birth weight in all babies and appeared to be directly proportional to it. The value for V̇O2/kg was similar in all groups. V̇O2 was not related to gestational age per se. However, in the two normally grown groups V̇O2 was roughly related to gestational age because birth weight was related to gestational age.4. In all babies minimal V̇O2 rose progressively with increasing age after birth; a marked increase in V̇O2 occured in the first week of life, despite a small decline in body weight.5. At a given age after birth differences in V̇O2/kg between the four groups were mostly less than 10%, and in general the differences were not statistically significant.Values for minimal V̇O2 in all four groups were roughly:5 ml. O2/kg.min at < 12 hr of age.7 ml. O2/kg.min at 7‐14 days of age.9 ml. O3/kg.min at about 2 months of age.6. It is concluded that:(a) At birth minimal V̇O2 is largely determined by birth weight. V̇O2/kg is little affected by either rate of growth in utero or gestational age.(b) Minimal V̇O2 is a function of age after birth as well as of body weight, and the value for V̇O2/kg increases as the baby gets older.
The effect of local blockage of motor nerve terminals
Authors: Katz B. , Miledi R. 
Published: December 2014

1. Electrophoretic application of tetrodotoxin (TTX) was used to study the effect of localized blockage of impulses in motor nerve terminals.2. Under suitable conditions it can be shown that local production of end‐plate potentials ceases distal to the site of TTX application, while it continues without diminution at proximal sites of the same terminal arborization.3. It is concluded that electrotonic spread of an action potential wave along a motor nerve terminal is insufficient to elicit transmitter release. Active propagation in the terminals is an essential requirement for neuromuscular transmission.
Three factors limiting the reliable detection of light by retinal ganglion cells of the cat
Authors: Barlow H. B. , Levick W. R. 
Published: December 2014

1. Responses of cat retinal ganglion cells have been examined with a view to specifying the characteristics that limit the detection of light stimuli.2. Threshold is defined as the weakest stimulus that can be reliably detected by examination of the output from a retinal ganglion cell; it depends upon (a) the quantum/spike ratio, which is the mean number of additional quantal absorptions required to produce an additional impulse, (b) the temporal course of the response, which determines the time interval within which the maintained discharge is modified, and (c) the statistical distribution of the number of impulses that occur in this time interval in the absence of the stimulus.3. The quantum/spike ratio changes greatly when adapting luminance is changed, and this is the predominant factor accounting for changes in increment threshold.4. The time course of the response changes with adaptation level and area of the stimulus. This may account for the changes in temporal integration that occur in analogous psychophysical experiments.5. Changes in the irregularity of the maintained discharge also affect the threshold of single ganglion cells. This is only a minor factor in the conditions of most of our experiments, but it may be important when unstabilized images and non‐equilibrium adaptation conditions are encountered.