bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbohydrate Metabolism in the Fetal Pig During Late Gestation
Authors: Comline R. S. , Fowden Abigail L. , Silver Marian
Published: December 2014

In acute experiments on pregnant sows under sodium pentobarbitone anaesthesia, acid base balance, oxygenation and plasma metabolite concentrations were well maintained in the dam and all fetuses which remained undisturbed in utero, irrespective of the duration of the experiment. Fetal liver glycogen concentrations were also unaffected by the time of removal of the fetus. By contrast, intravascular catheterization and withdrawal of blood led to fetal hyperglycaemia and depletion of hepatic glycogen although blood gas and pH values were not changed by these procedures. In the 1½‐2h sampling period following catheterization the normal positive umbilical venous‐arterial differences in plasma glucose and lactate generally became reversed. These changes were prevented by the administration of hexamethonium (10–15 mg.kg‐1 i.v.) but the drug did not block the fall in hepatic glycogen in catheterized fetuses. Both adrenaline and noradrenaline, which were each infused intravenously at 2·7–3·9 or 0·6–0·9 µg.kg‐1.min‐1. resulted in fetal hyperglycaemia and lacticacidemia together with a fall in arterial blood pH; hepatic glycogen concentrations in these fetuses were also reduced. The apparent sensitivity of the glycogenolytic mechanism to surgical trauma and haemorrhage in the fetal piglet is discussed in relation to findings in other species.
An Electrophysiological Study of Neurones in the Substantia Gelatinosa Rolandi of the Cat's Spinal Cord
Authors: Cervero F. , Iggo A. , Molony V.
Published: December 2014

Single unit neuronal activity has been recorded in the Substantia Gelatinosa Rolandi (SG) of the lumbar spinal cord of chloralose anaesthetized and gallamine paralysed cats. High impedance, fine tipped glass microelectrodes were used to record from the neurones of the SG. A set of five criteria was laid down to differentiate activity generated by SG neurones from activity produced by other neuronal elements. One hundred and ten neurones satisfied all the criteria and the sample consisted of 78 extracellularly and 32 intracellularly recorded SG neurones. The responses of these neurones to natural stimulation of the skin have been analysed. The majority (86%) showed a conspicuous and persistent background activity in the absence of intentional stimulation and a cutaneous receptive field from which they could be inhibited. These SG neurones have been called ‘inverse’ neurones because their response characteristics were the mirror image of larger neurones in Laminae I, IV and V of the dorsal horn. The background activity of the ‘inverse’ SG neurones was post‐synaptically generated; different in pattern from that of larger and deeper dorsal horn neurones and dependent on the afferent drive to the SG neurones. Three main groups of ‘inverse’ SG neurones could be distinguished according to the kind of natural stimulation that produced inhibition: (i) Class ‘inverse’ 1 ([unknown]), inhibited only by non‐noxious stimulation of the skin. (ii) Class ‘inverse” 2, ([unknown]) inhibited by both noxious and non‐noxious stimulation and (iii) Class ‘inverse’ 3 ([unknown]), inhibited only by noxious stimulation. Class [unknown] SG neurones were excited by noxious stimulation of their receptive fields and Class [unknown] SG neurones were activated by non‐noxious stimulation of theirs.

It is proposed that SG neurones control the transmission of all sensory messages through the spinal cord by tonically inhibiting the larger dorsal horn neurones in the absence of stimulation and by selectively releasing this inhibition during periods of stimulation.
The Role of Cation‐Activated ATPases in Transmitter Release from the Rat Iris
Authors: Reading H. W. , Isbir Turgay
Published: December 2014

Release of noradrenaline (NA) from isolated rat iris during perfusion in K+‐free medium was confirmed. Direct biochemical measurement of different cation‐activated ATPases did not reveal any definite relationship between Na+K+ ATPase and NA release. A significant increase in Ca++Mg++ ATPase activity was found on termination of NA release obtained by reintroduction of K+ to the medium. Criticism of the model for studying enzymatic control of transmitter release under physiological conditions is presented. It is suggested that removal of intracellular Ca++ ions by a calcium pump is directly associated with termination of transmitter release.
Responses of Systemic Vascular Smooth Muscle to Hypoxia
Authors: Ebeigbe A. B. , Pickard J. D. , Jennett Sheila
Published: December 2014

The rapidity and extent of hypoxic relaxation of vascular smooth muscle (VSM) from different systemic vessels is relevant to the study of mechanisms of vasodilatation in different vascular beds. Variations between sites may also assist understanding of the link between oxygen tension and mechanical activity, which has been shown not to be a simple deprivation of aerobic processes.

Strips of rat portal vein (RPV), rabbit ear artery (REA) and rabbit common carotid artery (RCC) were studied under isotonic conditions, contracted by 10–6 noradrenaline (NA). Reduction of Po2 to less than 3KPa during NA contraction led to relaxation which was rapid and 90% complete in RPV, rapid and 60% in REA: the relaxation began when tissue Po2 was decreasing and was not lower than 5·5 K Pa. RCC responded slowly and only some strips relaxed. The rapidity and magnitude of relaxation for each type of vessel was comparable to that produced by removal of external calcium. Also for any one type of VSM the response to NA was abolished or diminished to a similar extent by preliminary exposure to hypoxia, or by preliminary removal of calcium. Preliminary hypoxia diminished 50mmol.l–1 K+ contractions as much as it diminished NA contractions.

Preliminary 1—2 hour exposure to hyperoxia diminished the subsequent relaxant effect of hypoxia. Inhibition of glycolysis (iodoacetic acid) had no effect on normoxic NA contraction or on hypoxic relaxation, but prevented or diminished the subsequent recovery on reoxygenation. Low oxygen tension appears to act in VSM as though it interferes with net influx or utilisation of external calcium.
The Effects of pH on the Sodium‐Withdrawal Contractures Evoked from Frog Atrial Trabeculae
Authors: Chapman R. A.
Published: December 2014

Contractures can be evoked from frog atrial trabeculae by raising extracellular pH in Na‐free fluid after the spontaneous relaxation of the teision evoked by removineg extracellular Na. These alkalinity contractures are unffected by local anaesthetics but are absent following a brief perfusion with Ca‐free fluid containing EGTA. The application of ammonium chloride produces similar‐contractures which are unaffected by perfusion with Ca‐free fluid but are partially inhibited by local analesthetics. Perfusioni by solution containing a high Pco2 fails to induce contractures.

The relationship between [Na]o and tension is altered by changing extracellur pH: acidic fluids below pH 6·0 reduce tension and alkaline fluids increase tenision over the whole range. NH4Cl has the same effect as alkalinc fluids while CO2‐conitaining flid has no effect. These results can be interpreted if the effects of variation of extracelluar pH. on Na‐withdrawa; contractures, are mediated by changes in intracellular pH which in turn affect the Ca‐sensitivity of the contractile proteins.
IDENTIFICATION OF TWO STRAINS OF CULTURED CANINE RENAL EPITHELIAL CELLS (MDCK CELLS) WHICH DISPLAY ENTIRELY DIFFERENT PHYSIOLOGICAL PROPERTIES
Authors: Barker G. , Simmons N. L.
Published: December 2014

Cultured monolayers of Madin‐Derby canine kidney (MDCK) cells grown upon permeable filter supports display many features of in vivo epithelia. Measurements of transmonolayer resistance, open‐circuit p.d., dilution and bi‐ionic p.d.s have been made of MDCK monolayers mounted in Ussing‐type chambers (0·75 cm window radius). Previously reported values of transmonolayer resistance of 100 Ω cm2 (Cereijido, Robbins, Dolan, Rotunno & Sabatini, 1978 ; Misfeldt, Hamamoto & Pitelka, 1976) indicate a ‘leaky’ epithelium. The major finding of this work is that MDCK monolayers can also display values of transmonolayer resistance similar to ‘tight’ epithelia (mean value = 4116 Ω cm2). The reason for such differences is the existence of separate strains of MDCK cells. High‐resistance monolayers originate from cell stocks of sixty serial passages whilst low‐resistance monolayers originate from cell stocks of 109 serial passages. Measurements of transmonolayer dilution, and bi‐ionic p.d.s together with Na ion tracer fluxes and electron microscope observations of La3+ penetration through the apical tight junctions, substantiate the finding of high‐resistance properties in MDCK monolayers and confirm the existence of two separate MDCK cell strains displaying entirely different physiological properties. Differences extend to cellular morphology and cellular volume in the two strains of MDCK cells.
EFFECT OF DIETARY LINOLEIC AND LINOLENIC ACIDS ON GESTATION AND PARTURITION IN THE RAT
Authors: Leat W. M. F. , Northrop Christine A.
Published: December 2014

Six rats fed a basal, purified diet low in essential fatty acids gave birth to a total of twenty‐eight pups, of which twenty‐six were born dead (range of two to six pups per rat) after a mean gestation of 24 days. A seventh rat carrying ten fetuses had a protracted process of parturition with dystocia. Six rats fed the basal diet supplemented with linoleate gave birth to a total of sixty‐one pups of which fifty‐seven were born alive (range of two to fourteen pups per rat) after a mean gestation of 21·8 days. Seven rats fed the basal diet supplemented with linolenate and carrying a total of sixty‐three fetuses (seven to twelve per rat) had a protracted process of parturition with dystocia, and only one live and one dead pup were born (mean gestation of 22·8 days). At Caesarian operation a marked uterine inertia was noted. In four more rats where the supplement of linolenate was replaced by linoleate from the seventeenth day of gestation, parturition appeared normal and twenty‐nine live and four dead pups were born. The occurrence of dystocia appeared to be related to the number of fetuses being carried to term. It is concluded that, in the rat, linolenate satisfies the requirement for the growth of mother rat and of the fetuses but is inadequate for the normal process of parturition, probably through inadequate production of the prostaglandins involved. There appears to be an obligatory requirement for linoleate at parturition.
EFFECTS OF β‐ENDORPHIN, VASOACTIVE INTESTINAL POLYPEPTIDE AND CHOLECYSTOKININ OCTAPEPTIDE ON CAT CAROTID CHEMORECEPTOR ACTIVITY
Authors: McQueen D. S. , Ribeiro J. A.
Published: December 2014

The effects of β‐endorphin, vasoactive intestinal polypeptide (VIP) and cholecystokinin octapeptide (CCK‐8) on carotid chemoreceptor activity have been investigated in cats anaesthetized with pentobarbitone. Spontaneous chemoreceptor discharge was decreased by intracarotid injection of β‐endorphin and by low doses of VIP, whereas it was increased by CCK‐8 and higher doses of VIP, these effects being relatively long‐lasting and often associated with changes in systemic blood pressure. The chemoexcitation evoked by acetylcholine and sodium cyanide was reduced during intracarotid infusion of any of the three peptides studied, and that caused by CO2‐saturated Locke solution was reduced by β‐endorphin, largely unaltered by VIP and variably affected by CCK‐8. The inhibitory effect of β‐endorphin was greatly reduced by naloxone, implying that it probably involved actions at naloxone‐sensitive opiate receptors in the carotid body. Substance P was unable to overcome the chemoinhibitory effect of methionine enkephalin. Possible functions of polypeptides in the carotid body are discussed.
REFLEX RESPONSES OF SINGLE RENAL SYMPATHETIC FIBRES TO STIMULATION OF ATRIAL RECEPTORS AND CAROTID BARO‐ AND CHEMORECEPTORS
Authors: Kidd C. , Linden R. J. , Scott Evelyn M.
Published: December 2014

Recordings were made of the discharge of single fibres from renal sympathetic efferent nerves in the anaesthetized dog. Stimulation of left atrial receptors by distension of small balloons at the junctions of the pulmonary veins and the left atrium resulted in a reduction in the discharge of one group of these single fibres and no change in the discharge of a second group of fibres. Bilateral occlusion of the common carotid arteries resulted in an increase in the discharge of all single fibres tested. All fibres tested which responded to stimulation of atrial receptors also responded to carotid occlusion. These results provide evidence for convergence of the central pathways from atrial receptors and baroreceptors on individual sympathetic efferent neurones.
EFFECTS OF INCREASED BLOOD AMMONIA CONCENTRATIONS ON THE CONCENTRATIONS OF SOME METABOLITES IN RAT TISSUES
Authors: Wiechetek Maria , Breves G. , Höller H.
Published: December 2014

Rats were given ammonium chloride intravenously (5 and 10 mg per 100 g body weight) and sacrificed 30 sec, 5 min and 30 min after injection. Ammonia concentrations were determined in brain, liver, skeletal muscle and epididymial fat, and glycogen, glucose, pyruvate, lactate, ATP and cyclic AMP were assayed in brain, liver and muscle. In control animals, muscle and fat showed a high capacity for ammonia accumulation. After injection of NH4Cl the ammonia concentration increased in all tissues analysed, particularly in muscle and fat, where ammonia concentrations remained elevated for 30 min. In brain, glycogen was reduced whereas glucose, pyruvate, lactate and cyclic AMP levels were raised. In liver, glycogen was lower and glucose higher than in controls. ATP concentrations were unchanged in both tissues. In muscle samples taken 30 sec and 5 min after dosing, glycogen concentrations were not affected but glucose, pyruvate and lactate concentrations were reduced and ATP concentrations were increased. In muscle samples taken after 30 min metabolite concentrations were normal again but glycogen concentrations had dropped.
RAPID CEREBRAL VASODILATATION IN BRIEF HYPOXIA IN ANAESTHETIZED ANIMALS
Authors: Jennett Sheila , Pitts L. H. , North J. B.
Published: December 2014

In anaesthetized dogs, cats and rabbits, intracranial pressure was measured continuously during brief or transient hypoxia, induced by (a) lowering inspired O2 to 9–10% for 2–3 min, or (b) giving 2–3 breaths of nitrogen. In almost all instances there was an increase in i.c.p. which started in less than 20 s; this occurred with either spontaneous or controlled ventilation, and whether or not there was also a rise in arterial blood pressure; the time course was similar to that of the arterial chemoreceptor reflex responses of ventilation and blood pressure. Division bilaterally of the sinus and vagus nerves in six cats showed that the intracranial pressure response was not dependent on these chemoreceptor afferent pathways. The results suggest a rapid vasodilatation starting at a time when cerebral arterial oxygen tension is unlikely to be below 7 kPa (50 mmHg). The mechanism remains unexplained.
THE INFLUENCE OF INTRAVENOUS GLUCOSE ON BODY TEMPERATURE
Authors: Green J. Hilary , Macdonald I. A.
Published: December 2014

The influence of an intravenous infusion of glucose (500 ml of 20% w/v), on heat production and variables which contribute to heat loss was studied in six normal human volunteers. Mannitol (500 ml of 20% w/v) was infused on a different occasion as an osmotic control. Both infusions produced changes in haematocrit and osmolality of a similar magnitude. Heat production increased by 20% after intravenous glucose but only a small increase in heat production was observed after intravenous mannitol. Calf blood flow increased after both infusions but hand blood flow increased only after the glucose infusions. The increase in skin temperature which was observed after both infusions was associated with increases in peripheral blood flow. Core temperature decreased slightly following administration of both substances. The changes in metabolic heat production and cardiovascular function are discussed. These changes do not appear to be due to the catecholamine response to hyperglycaemia and hyperosmolality.
AN UNUSUAL SYNAPTIC RESPONSE MEDIATED BY A SEROTONIN NEURONE
Authors: Cottrell G. A.
Published: December 2014

Impulse activity in an identified serotonin‐containing neurone produces a delayed slow excitatory response in another identified neurone. An axon of the serotonin neurone passes very close to the follower neurone perikaryon. The synaptic response is frequently accompanied by oscillations of the membrane potential. Constant‐current pulsing experiments suggest that it could result from a reduction in membrane conductance. The response is markedly voltage‐sensitive, being greatly reduced at potentials in excess of about −55 mV. Serotonin, locally applied, produces a very similar effect. The response to serotonin does not involve a change in conductance to either Na+ or Cl−, but Ca2+ appears to be involved, either by virtue of its influence on K+ conductance, or directly in its transfer of charge across the membrane.
TEMPERATURE DEPENDENCE OF THE SODIUM CHANNEL GATING KINETICS IN THE NODE OF RANVIER
Authors: Collins Carol A. , Rojas E.
Published: December 2014

Temperature dependence of the Na+ channel gating kinetics was measured from the ionic and charge displacement currents in the node of Ranvier of Xenopus laevis. m3h kinetics was applied, assuming a delay, δt, in the activation process. The rate constants for the m‐ and h‐process showed Arrhenius temperature‐dependence with Q10 of 2·34 and 2·9 respectively, while δt exhibited non‐Arrhenius temperature‐dependence. Q10 for [unknown]PNa, measured as 1·6, was smaller than for the rate constants and similar to that for a diffusion process. A negative shift and decrease in voltage sensitivity of the steady‐state curves, h∞ and m∞, occurred with decreasing temperature. The maximum time constant obtained from a single exponential fit to the displacement currents during the pulse for times greater than 90 µs exhibited Q10 of 2·01, which lies between that for [unknown]PNa and that for τm.
THE RENAL KALLIKREIN‐KININ SYSTEM AND SODIUM EXCRETION
Authors: Mills Ivor H.
Published: December 2014

Renal kallikrein is a glandular type kallikrien situated in the distal tubular cells and is released into both the urine and the renal lymph. In the vasculature it lowers blood pressure and increases vascular permeability. Blood volume expansion with 0·9% saline or 2·5% glucose leads to a large increase in kallikrein release which, by its effect on the vasculature, helps to maintain dynamic equilibrium. Kallikrein is also released by increase of renal artery pressure or by renal vasodilators. Very small doses of noradrenaline release kallikrein via prostaglandin E as intermediate. Hypertensive doses of angiotensin release kallikrein, partly via prostaglandin and partly by a direct pressure effect. During escape from the sodium‐retaining effect of steroids, kallikrein excretion is increased but it is not released by the acute infusion of aldosterone into the renal artery.

The kallikrein‐kinin system antagonizes the renin‐angiotensin system, causes dilution of urine and increases sodium excretion unless renal artery pressure is low. Increased blood pressure can produce natriuresis without involving the kallikrein system, perhaps through release of natriuretic hormone.
QUANTITATIVE LIGHT AND ELECTRON MICROSCOPIC STUDIES ON THE VENTRAL ROOTS OF THE WOBBLER MUTANT MOUSE
Authors: Biscoe T. J. , Lewkowicz S. J.
Published: December 2014

In wobbler mutant mice and normal litter‐mates the numbers of axons have been counted in cervical and lumbar ventral roots and the dimensions of nerve fibres measured in the fifth cervical, C5, and third lumbar, L3, roots. In wobbler cervical ventral roots C5, C7 and C8 and lumbar roots L4 and L5 the number of axons was reduced. Abnormal features were seen in all mutant cervical ventral roots but not in the lumbar roots. The histogram of fibre size was shifted to the left in the wobbler C5 roots where axon loss was considerable, particularly amongst the large diameter axons, and in L3 roots where, although there was no over‐all loss of axons, there were fewer ventral root fibres of large diameter. Abnormal features were also observed in a few dorsal root ganglion cells.
THE CAROTID BODY CHEMORECEPTOR: AN INVESTIGATION IN THE MOUSE
Authors: Biscoe T. J. , Pallot D. J.
Published: December 2014

The carotid body chemoreceptor has been investigated in the normal mouse and in the wobbler mutant. Electron microscopic studies show that the synaptic vesicle‐containing nerve endings on type I cells are reduced in number in the mutant to 4·2% of the normal number. The function of the chemoreceptors was examined by recording ventilation and testing the response to different inspired gases and to the intra‐arterial injection of cyanide. In addition recordings of chemoreceptor activity were made from the sinus nerve. No distinction could be drawn between the normal and the mutant mouse. No relationship was found between chemoreceptor activity and the respiratory cycle. If the synaptic vesicle‐containing endings are afferent then only 4·2% of the normal number appear to be needed for normal function.
CHLOROTETRACYCLINE FLUORESCENCE ASSOCIATED WITH PLASMA MEMBRANES OF COCKROACH SALIVARY GLAND CELLS
Authors: Gray D. C. , House C. R.
Published: December 2014

The fluorescent compound chlorotetracycline (CTC) enters the cells of the cockroach salivary gland. The acinar peripheral cells and the non‐secretory duct cells become preferentially labelled by CTC. Microscopic examination of the intracellular distribution of CTC indicates that this compound labels the highly folded apical plasma membranes of the peripheral cells and the deep infolds of the basal plasma membranes of the non‐secretory duct cells. Lanthanum blocks the entry of CTC into all of the gland cells and in this condition the CTC labels the basal surfaces of the acini and ducts. The results of this investigation support the idea that CTC labels calcium ions in the vicinity of plasma membranes.
APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY TO STUDY TRANSPORT AND METABOLISM OF NUCLEIC ACID DERIVATIVES BY RAT JEJUNUM IN VITRO: ENDOGENOUS WASHOUT
Authors: Parsons D. S. , Shaw M. I.
Published: December 2014

A procedure is described for maintaining segments of rat jejunum in vitro in a steady state of fluid and solute absorption for periods of up to 2 h so that the secretion of endogenous and exogenous nucleic acid derivatives across the serosa may be followed. Methods of high performance liquid chromatography for the separation and measurement of some nucleic acid derivatives are also described. These procedures are applied to investigate three endogenous components found in the washout into the serosal secretions. The kinetics of the washout are, in each case, mono‐exponential and the effects of pre‐feeding, of pre‐feeding a glucose solution and of the diabetic state on the washouts have been investigated. One of the components of the washout is uric acid, the initial pool size of which varies from 13–22 µmol/g dry wt. of jejunum. Negligible amounts of derivatives of endogenous origin appear in the lumen.
EFFECTS OF 5‐HYDROXYTRYPTOPHANE AND INSULIN ON GASTRIC MOTILITY AND EMPTYING IN DOGS
Authors: Pröve J. , Ehrlein H. J.
Published: December 2014

In unanaesthetized dogs gastroduodenal motility was investigated by simultaneous transducer recordings and fluoroscopy; gastric emptying was measured via a duodenal cannula. Intravenous infusion of 5‐hydroxytryptophane enhanced both gastric emptying and antral and duodenal motility. The intravenous injection of insulin was followed by an initial inhibition of antral and duodenal motility and of gastric emptying. In a second phase antral and duodenal contractions were augmented, while the proximal stomach relaxed. Thereby, gastric emptying increased only slightly in spite of the strong antral activity. It is concluded that several factors are involved in controlling gastric emptying.
LOCAL CONTROL OF TESTICULAR FUNCTION
Authors: Sharpe Richard M.
Published: December 2014

This review has shown that local control of testicular function exists at three different levels. (1) Regulation of the entry of substances into the testis via the operation of selective barriers at the level of the capillary endothelium, myoid layer and Sertoli cell tight junctions, and by control of the rate of interstitial fluid formation which is the medium for transport into and within the testis. These mechanisms permit the creation of specific micro‐environments around the Leydig cells and outside of the seminiferous tubules as well as within the tubules, prerequisites for the local interaction and communication summarized below. (2) Regulation of spermatogenesis by co‐ordination of changes in hormone responsiveness and function of the Sertoli cells with the requirements of the associated germ cells, this varying according to the stage of the spermatogenic cycle. These changes involve regulation of germ cell multiplication, their differentiation and translocation from the basal to the adluminal compartment of the seminiferous tubule and their release into the lumen. (3) Interaction between the seminiferous tubules and the Leydig cells via various factors. The purpose of this interaction is not certain but in the prepubertal testis it probably co‐ordinates development of the tubules and Leydig cells, whilst in the adult testis it probably functions to regulate the steroidogenic responsiveness of the Leydig cells in accordance with the stage‐dependent requirements of the adjacent seminiferous tubules.

Local control mechanisms within the testis therefore appear to co‐ordinate the function of the different cell types in the two testicular compartments and, as this is essential for normal function of the testis, the importance of local factors is self‐evident. In each of the three areas there is still only limited information as to the precise operation of the various mechanisms and even less is known about the identity of the co‐ordinating agents. But, as most of the available information derives only from the last three years, the gaps in our knowledge are to be expected and it is certain that the next few years will see major advances in this area. If the interpretation of the data offered in this review proves accurate then we are on the threshold of a revolution in our understanding of the control of testicular function, and of spermatogenesis in particular. This can only lead to improved methods for regulation of fertility in the male.
SEROTONIN, AND MOUSE SPINAL NEURONES IN CELL CULTURE
Authors: Green K. A. , Cottrell G. A.
Published: December 2014

Two different responses to serotonin have been observed. One response was a depolarization accompanied by a decrease in membrane conductance. This response was enhanced at depolarized potentials and reduced at hyperpolarized potentials; the apparent conductance change was also reduced at hyperpolarized potentials indicating some voltage sensitivity of the response. The other response was a depolarization accompanied by an increased membrane conductance. The response was enhanced at hyperpolarized potentials and reversed to a hyperpolarization at −35 to −60 mV. The total number of responsive neurones was small (5%). This might be explained by a deficiency of serotonergic input to the recorded cells, since it was shown autoradiographically that very few neurones in the cultures used exhibited a specific high‐affinity uptake for the transmitter, and hence probably contained it.
A POSSIBLE ROLE FOR INTRACELLULAR SODIUM IONS IN THE CONTROL OF CONTRACTION IN FROG ATRIAL TRABECULAE BY WAY OF THE SODIUM‐CALCIUM EXCHANGE
Authors: Chapman R. A. , Tunstall J.
Published: December 2014

The effect of various inotropic agents on the strength of the Na‐withdrawal contracture of isolated frog atrial trabeculae has been determined. Increasing the heart rate (0·1 min−1 to 40 min−1), exposure to low external K concentration ([K]o) (1‐0·3 mmol.l−1), to strophanthidin (10 nmol.l−1 to 10 µmol.l−1) and to the ionophore monensin (10 nmol.l−1 to 100 µmol.l−1) all cause a progressive increase in the strength of the Na‐withdrawal contracture, so that the curve relating external Na concentration ([Na]o) to contracture tension is shifted towards higher values of [Na]o. By contrast adrenaline (1 nmol.l−1 to 1 µmol.l−1) causes a decrease in the strength of Na‐withdrawal contractures. As increased heart rate, the application of K‐depleted fluids, strophanthidin or monensin are likely to increase internal Na concentration ([Na]i), the change in relationship between [Na]o and contracture tension can be fitted using equations for a 3 Na+ for 1 Ca2+ exchange and for pCa vs. relative tension, by varying the apparent [Na]i. The increased Na influx necessary to change [Na]i by the amount suggested b‐‐‐y these calculations agrees well with direct measurements made by other workers. A similar relationship is observed between the strength of the heart beat and the calculated [Na]i for the effects of increased heart rate, the application of strophanthidin, low [K]o or monensin. The effects of adrenaline, however, cannot be interpreted in the same way, suggesting that at least one other process mediates the strength of the heart beat. Various possibilities are discussed.
IMMUNOCYTOCHEMISTRY AND NEUROBIOLOGY
Authors: Cuello A. Claudio , Priestley John V. , Sofroniew Michael V.
Published: December 2014

Immunocytochemistry enables the localization of transmitter‐related antigens in tissue sections at either the light microscopic or the electron microscopic level. In the case of neuropeptides and certain transmitters (e.g. serotonin) it has been possible to produce antibodies directed against the putative transmitter itself. In other cases it has not been possible to produce useful antibodies against transmitters but antibodies have been raised against enzymes involved in transmitter metabolism (e.g. tyrosine hydroxylase, glutamic acid decarboxylase) and these antibodies are suitable markers for transmitter systems.

Successful immunostaining with an antibody depends on a number of factors, two of the most important being the fixation of the antigen in the tissue and the visualization of the primary antibody once it has bound to the antigen. Techniques available for the visualization of bound primary antibody include the indirect‐labelled immunofluorescence procedure and the unlabelled peroxidase‐antiperoxidase (PAP) procedure. Direct‐labelled immunocytochemistry is not now widely used but is likely to become increasingly important with the introduction of monoclonal antibodies and the development of techniques for the simultaneous localization of multiple antigens. Monoclonal antibody procedures also allow the production of antibodies against antigens which are difficult to purify such as certain transmitter markers (e.g. choline acetyltransferase) and constituents of neuronal membranes.

Immunocytochemistry allows the production of detailed maps of the distribution of putative transmitters in the nervous system and in combination with tract tracing procedures is being used increasingly to identify transmitters in neuronal circuits. It has also been important in establishing the transmitter status of various neuroactive compounds in single neurones. Immunocytochemistry can be carried out on post‐mortem samples and is providing information on transmitter distribution in normal and abnormal human brain.
THE EFFECT OF STIMULATION OF ATRIAL RECEPTORS ON THE PLASMA CONCENTRATION OF VASOPRESSIN
Authors: Bennett K. L. , Linden R. J. , Mary D. A. S. G.
Published: December 2014

The effect of stimulation of the left atrial receptors on plasma concentration of vasopressin and urine flow was studied in dogs anaesthetized with chloralose. Distending a large balloon in the left atrium, so as to occlude the mitral valve and increase left atrial pressure, consistently resulted in a decrease in plasma vasopressin and an increase in urine flow. Discrete stimulation of the left atrial receptors, by distending small balloons in the pulmonary vein ‐ left atrial junctions and in the left atrial appendage, consistently resulted in a decrease in plasma vasopressin and an increase in urine flow. The left atrial receptors were stimulated discretely in dogs in which bretylium tosylate, atropine and atenolol had been administered. In these dogs distension of the small balloons was not associated with significant changes in heart rate, left atrial pressure or arterial blood pressure and consistently resulted in a decrease in plasma vasopressin and an increase in urine flow. It is concluded that this decrease in the plasma concentration of vasopressin is a direct result of discrete stimulation of the atrial receptors and is not secondary to any haemodynamic changes. The exact role of this decrease in plasma concentrations of vasopressin in the diuretic response to stimulation of the left atrial receptors remains to be established.
VENTILATION, GASEOUS EXCHANGE AND AIR SAC GASES DURING MODERATE THERMAL PANTING IN DOMESTIC FOWL
Authors: Gleeson Michael , Brackenbury John H.
Published: December 2014

Gaseous exchange, ventilatory pattern and gas levels within the interclavicular and abdominal air sacs of domestic fowl were monitored before, during and after periods of moderate hyperthermic panting. O2 consumption (VO2) remained virtually unaltered and CO2 production (VCO2) increased slightly during panting as compared to normal respiration. Resting VO2 was 12·2 ml.kg−1.min−1. Resting (eupneic) PO2 and PCO2 of the interclavicular and abdominal air sacs were 100·1 and 38·5 torr, and 125·2 and 16·4 torr respectively. During panting the partial pressure of the abdominal air sac Pabs, O2 and Pabs, CO2 fell and rose to extreme values of 109 and 29·8 torr respectively. Simultaneously the partial pressure of the interclavicular air sac Pics, O2 and Pics, CO2 changed by smaller amounts to 107·5 and 32·3 torr respectively. Ventilatory pattern during thermal panting was characterized by rapid, shallow movements which were interrupted at regular intervals by short sequences of slower, deeper breaths. During these intermittent periods of eupneic breathing gas levels returned towards normal and these alterations were reflected in transient variations in VO2 and VCO2 about their mean values. Changes in gas levels within the lung‐air sac system are discussed in connexion with the peripheral control of ventilation during panting.
LIMINAL AND SUPRALIMINAL RESPONSE CHARACTERISTICS OF MECHANORECEPTORS OF THE HAIRY AND FOOT PAD SKIN OF CAT DETERMINED WITH SHORT TACTILE PULSES
Authors: Hämäläinen Heikki , Pertovaara Antti
Published: December 2014

The liminal and supraliminal response characteristics of mechanoreceptive units innervating the hairy skin and glabrous foot pad of the cat were determined with single pulses of varying frequency (20, 60 and 150 Hz) in order to compare the characteristics of mechanoreceptors in cat and man. Altogether 172 units were tested. The units were divided into slowly adapting (s.a.) (I and II), rapidly adapting (r.a.) and pacinian (p.c.) units. No hairy skin p.c. units were encountered. The absolute thresholds and supraliminal responses of units innervating the hairy skin resembled those of human hairy skin mechanoreceptors, the s.a. II units having the lowest thresholds and both s.a. and r.a. units having lower thresholds as a function of increasing frequency of the pulse. The results suggest that on the hairy skin detection thresholds are based on activation of mainly s.a. II units, whereas the role of r.a. units is of importance for distinct touch and supraliminal sensations. S.a. units of foot pads were different if compared to s.a. units of human glabrous skin. R.a. and p.c. units in foot pads were similar to corresponding human units and the low detection and touch thresholds on the glabrous skin are explicable on the response properties of r.a. and p.c. units. According to the present study the results concerning response characteristics of cat hairy skin s.a. and r.a. units and cat glabrous skin r.a. and p.c. units can be applied to human psychophysical studies in the corresponding areas.
COLLOIDAL GOLD AND BIOTIN‐AVIDIN CONJUGATES AS ULTRASTRUCTURAL MARKERS FOR NEURAL ANTIGENS
Authors: Van Den Pol Anthony N.
Published: December 2014

The use of two new reagents, biotin‐avidin conjugates and colloidal gold particles, for ultrastructural immunocytochemistry has been reviewed, and their potential for immunocytochemistry in the central nervous system has been discussed. Although these compounds have been used very little in the C.N.S. in the past, with their high sensitivity, versatility, and potential for simultaneous localization of two antigens with two electron dense markers, these reagents may prove very useful for answering a number of neural questions.

Colloidal gold adsorbed to immunoglobulins can be used for light microscopic observation, and owing to its high electron density and ability to readily adsorb to immunoglobulins, protein A, and antigen‐carrier complexes, it also serves as an excellent immunomarker at the ultrastructural level. Several procedures have been described for the use of pre‐and post‐embedding immunostaining with colloidal gold particles. Different size gold particles, adsorbed to different antibodies can be used for pre‐and post‐embedding staining of different antigens in the same tissue. While at the light microscopic level only the large particles are visible as a pink haze, a fluorescent step can be added to allow easy identification and characterization of neurones labelled with any size colloidal gold, even if the pink colour of the gold is not visible. These same sections can subsequently be studied ultrastructurally. Unlike enzymatic methods, gold particles have less tendency to obscure ultrastructure.

Biotin can be easily conjugated to immunoglobulins and, due to its high affinity for avidin (1015 M−1) which has four biotin binding sites, can be localized with avidin markers, or biotin‐avidin‐ marker complexes. Some procedures such as the avidin‐biotin‐peroxidase complex are extremely sensitive. Biotin and avidin can be bound to a number of different markers including peroxidase, colloidal gold, and ferritin.

Photomicrographs from our hypothalamic work have been used to illustrate the histological results of some of the procedures described.
DOPAMINE AND LIPOLYSIS IN ADIPOSE TISSUE OF THE SHEEP
Authors: Thompson G. E.
Published: December 2014

An inguinal fat pad preparation suitable for blood flow and lipolysis studies in the sheep is described. Infusion of dopamine at the rate of 0·8 µg/min for 40 min increased blood plasma flow through the preparation, and increased the output of glycerol in its venous effluent suggesting fat mobilization. Infusion at the rate of 0·05 µg/min had no detectable effect, and the responses to infusions at 15 µg/ min were irregular. Dopamine, which is known to be present in sheep adipose tissue, may have a role in the regulation of blood flow and lipolysis.
MITOCHONDRIAL OXIDATIVE ENZYME ACTIVITY IN INDIVIDUAL FIBRE TYPES IN HYPO‐ AND HYPERTHYROID RAT SKELETAL MUSCLES
Authors: Johnson M. A. , Turnbull D. M.
Published: December 2014

Quantitative cytochemical and biochemical techniques have been used in combination to study the response of mitochondrial oxidative enzymes in individual muscle fibre types to hypo‐ and hyperthyroidism. Hypothyroidism resulted in decreased activity of succinate dehydrogenase (SDH), L‐glycerol‐3‐phosphate dehydrogenase (L‐GPDH), and D‐3‐hydroxybutyrate dehydro‐genase (D‐HBDH) in all fibre types of both slow‐twitch soleus and fast‐twitch extensor digitorum longus (e.d.l.) muscles. In hyperthyroidism, only L‐GPDH activity increased in e.d.l. but more marked increases were seen in soleus muscles, which also showed increased SDH activity. In addition to these alterations in the enzyme activity in individual fibre types the metabolic profile of the muscle is further modified by the hormone‐induced interconversion of slow‐ to fast‐twitch fibres and vice versa.
MORPHOMETRY OF THE ULTRASTRUCTURE OF THE BLOOD‐JOINT BARRIER IN THE RABBIT KNEE
Authors: Knight A. D. , Levick J. R.
Published: December 2014

The ultrastructure of the barrier to water and solute exchange between blood and a synovial cavity was studied morphometrically in five rabbit knees. The synovial surface consisted of 80% synoviocytes and 20% interstitium in direct contact with synovial fluid. The surface intercellular gaps were wide (0·1–5·5 µm). A rich network of capillaries lay just beneath the surface, the commonest (modal) depth of the capillary perimeter being 5 µm at its nearest point. Of these capillaries, 91% were fenestrated in adipose synovium, 44% in areolar synovium and 21% in posterior synovium; the remainder were continuous capillaries. The number of fenestrae per fenestrated capillary was low (∼0·5 µm–1, circumference: ∼6 µm−2). The fenestrae (width 52 nm; membrane thickness 3–4 nm) occupied ∼1% of the fenestrated endothelial surface‐area. Nuclear segments and intercellular junctions were roughly twice as frequent in continuous capillaries as in fenestrated capillaries of the same circumference, indicating that continuous endothelial cells are of smaller surface area than fenestrated cells. The basement membranes of continuous and fenestrated synovial capillaries were relatively thick (98 and 110 nm respectively), perhaps supporting the synovial endothelium during joint motion. In both fenestrated and continuous capillaries the nuclei were preferentially oriented away from the synovial surface (92 and 67% respectively), which presumably facilitates exchange with the surface.
THE EFFECTS OF FASTING ON CORE TEMPERATURE, BLOOD GLUCOSE AND BODY AND ORGAN WEIGHTS IN RATS
Authors: Chatamra K. , Daniel P. M. , Lam D. K. C.
Published: December 2014

Male Wistar rats of about 300 g body weight were fasted from 1 to 7 d. They were weighed and had their temperature taken daily. At the end of the experimental period, they were anaesthetized and blood was taken for measurement of the glucose content. The animals were killed and various organs were taken and weighed. Over the first 24 h there were striking reductions in body weight, core temperature and level of blood glucose. Throughout the succeeding days of fasting, there was a gradual decrease in body weight and core temperature, while the level of the blood glucose was maintained at about 3 mmol. l−1. The decrease in body weight and core temperature was matched by the weight loss of the liver and skeletal muscles. The heart and the kidney and spleen were not affected over the first day, but thereafter their weight declined steadily. The brain, the testes and the lungs retained their mass throughout.
PERINATAL DEVELOPMENT OF TUBULAR FUNCTION IN THE PIG
Authors: Alt J. M. , Colenbrander B. , Forsling M. L. , MacDonald A. A.
Published: December 2014

Renal tubular function has been studied in pig fetuses of 105–112 d gestational age in new‐born pigs 5–9 d old. The experiments were performed on anaesthetized animals, urines being collected by inserting a catheter into one ureter of the animal under study. The glomerular filtration rate was estimated and plasma concentrations and urinary excretion of the following substances were measured: sodium, potassium, calcium, ammonia, urea, phosphate, glucose, fructose, creatinine, protein and exogenous 4‐aminohippuric acid, and inulin. The reabsorption of water was considered in relation to the plasma vasopressin values. New‐born pigs were loaded with glucose and fructose in order to determine the maximal tubular transport rate of these substances. Significant changes at birth occur in only a few functions of the tubulus system. Following delivery, major changes are: (1) the increased reabsorption of sodium and water which is probably the most important adaptation to extra‐uterine life; (2) an apparent increasing impermeability of the tubular epithelium for creatinine, and (3) the direction of transport of fructose, which is reabsorbed by fetuses whereas neonates demonstrate a net secretion. Glucose and fructose are transported by different mechanisms. The experiments with fructose‐loaded piglets demonstrate that there are at least two transport mechanisms for fructose: reabsorption — either passive or active ‐ and secretion. The factors causing a shifting from one mechanism to the other are not yet known.
POST‐NATAL CHANGE IN THE EFFECT OF DENERVATION ON THE RAT VAS DEFERENS
Authors: Chiu‐Wei Yen‐Fun , Kasuya Yutaka , Watanabe Minoru
Published: December 2014

The vas deferens of 14–54 d old rats was denervated, isolated after 7 d, divided into prostatic and epididymal halves, and denervation supersensitivity to noradrenaline, acetylcholine, methacholine and tetramethylammonium (TMA) was examined. The supersensitivity to any of these agonists did not appear in rats younger than 21 d of age. Thereafter a leftward shift of the dose‐response curve and an increase in the maximum contraction to noradrenaline were observed. The maximum contraction became progressively greater with development in the prostatic half but was approximately constant in the epididymal half. Supersensitivity to methacholine distinctly developed with age in the epididymal half. Only a subsensitivity to TMA was observed, suggesting that TMA acts on the nerve. The effect of denervation on the response to acetylcholine in the epididymal half resembled that to methacholine, and in the prostatic half resembled that to TMA. The developmental change in the effect of denervation on noradrenaline was discussed in relation to the full contractile ability of the vas halves, and that to cholinergic drugs was discussed in relation to nicotinic and muscarinic receptor population.
EVIDENCE FOR GLUCOSE STIMULATION OF INTRACELLULAR BUFFERING OF CALCIUM IN THE PANCREATIC β‐CELL
Authors: Hellman Bo , Gylfe Erik
Published: December 2014

Glucose‐induced movements of Ca2+ in pancreatic β‐cells were analysed using islets isolated from ob/ob mice and insulin‐releasing cells from a clonal cell line (RINm5F). Addition of glucose to a perifusion medium resulted in an inhibited efflux of 45Ca from the islets both when the extracellular Ca2+ concentration was lower or higher than that in the cytosol. Glucose inhibition of 45Ca efflux was seen also after altering the Na+ gradient across the plasma membrane provided that the cytosolic K+ activity was maintained. The glucose suppression of 45Ca efflux corresponded to a stimulated net uptake of Ca2+ in the RINm5F cells. Also in this case the glucose effect was maintained when Na+ was replaced with K+ and suppressed after substitution with choline. During perifusion of islets with a Ca2+‐deficient medium the removal of glucose resulted in a temporary stimulation of insulin release. The results suggest that glucose, in addition to stimulating the entry of Ca2+, also promotes active sequestration of the ion in intracellular stores. The balance between these processes will determine the activity of cytosolic Ca2+ and consequently the rate of insulin release.