bluuebunny/crossref_metadata_2025 huggingface dataset:
Efferent Fibres to the Aortic Bodies: A search for Their Cell Bodies in the Brainstem of the Cat and Rabbit
Authors: Kidd C. , McWilliam P. N.
Published: December 2014

An attempt has been made to determine where in the lower brainstem the cell bodies of nonsympathetic efferent fibres in the aortic nerve of the cat and rabbit are located. Horseradish peroxidase (HRP) was placed on the central end of the right cut aortic nerve of anaesthetized animals and, after an appropriate time, sections of the brainstem encompassing the rostral and caudal limits of the dorsal vagal motor nucleus and nucleus ambiguus were examined microscopically for retrogradely transported HRP. Cell bodies labelled by exogenous HRP were not found in any of the cats or rabbits exposed to HRP although reaction product, due to an endogenous response, was observed. Appropriate control experiments were performed to show that the sensitivity of the technique for demonstrating HRP in our hands was adequate.

We conclude that the cell bodies of efferent fibres, of non sympathetic origin, in the aortic nerve are likely to be located outside the central nervous system.
The Arrangement of Endocrine and Exocrine Pancreatic Microcirculation Observed in the Living Rabbit
Authors: Fraser P. A. , Henderson J. R.
Published: December 2014

1. The microcirculation of the pancreas in the anaesthetized rabbit was examined by in vivo microscopy and micro‐cinephotography.

2. The islets of Langerhans were identified by their appearance following the systemic injection of diphenylthiocarbazone.

3. Arterial injection of Evans blue demonstrated the arrangement of vessels within the pancreas. Blood leaving the islets passed via capillaries into the capillary meshwork; no islet was ever seen to be drained directly by a vein.

4. The significance of this portal arrangement is discussed.
Changes in Renal Haemodynamics and Electrolyte Excretion after Intraventricular Infusion of Carbachol in Conscious Sheep
Authors: Beal A. M.
Published: December 2014

Infusion of carbachol at 10 nmol.min‐l for 30 min into one lateral cerebral ventricle of conscious sheep caused long‐lasting increases in arterial blood pressure, heart rate and haematocrit. The increase in haematocrit resulted from release of red blood cells from the spleen. The systemic cardiovascular changes were accompanied by increased glomerular filtration rate (G.F.R.), renal plasma flow (R.P.F.) and renal blood flow (R.B.F.) which did not return to pre‐carbachol levels within 180 min post‐carbachol. Intracerebroventricular (ICV) infusion of carbachol increased the rates of sodium excretion and clearance, potassium excretion and clearance, osmolal clearance and solute‐free water reabsorption and increased the concentration of vasopressin in arterial plasma. The increase in sodium excretion rate was caused by increased sodium filtration associated with a fall in the proportion of filtered sodium being reabsorbed. The increase in potassium excretion rate resulted mainly from increased potassium secretion possibly stimulated by increased distal sodium delivery and by increased vasopressin levels. The observed effects of ICV carbachol infusion resembled those previously reported for ICV infision of hyperosmotic sodium solutions.
The Depressive Action of Ammonium Chloride on the Hepatic Blood Flow in Sheep
Authors: Barej Wieslaw , Siwecka Barbara , Gronczewski Jacek , Skolasinska Krystyna
Published: December 2014

Using the 133Xe clearance method it is shown that NH4Cl infusion into the anterior mesenteric vein decreased capillary blood flow in the liver. Phentolamine completely and propranolol partially prevented the depressive action of NH4Cl on hepatic blood flow. NH4Cl infused into the jugular vein provoked a slight increase in the hepatic blood flow. The adrenaline‐like action of ammonium ion on the blood circulation in the liver region is discussed.
Resting Metabolism of Inorganic Phosphorus and Changes During Mechanical Activation in Perfused Muscle Fibres from Balanus
Authors: Nassar‐Gentina Verónica , Rojas E.
Published: December 2014

The levels of inorganic phosphorus (Pi), arginine (and indirectly N‐phosphoryl arginine) and adenosine triphosphate (ATP) were measured in intact and perfused muscle fibres from the barnacle Megabalanus psittacus, in resting conditions and during mechanical activity. A twitch caused the liberation of Pi to the intracellular perfusion solution and there was a corresponding decrease in the content of N‐phosphoryl arginine of the muscle fibre. Mechanical activation did not induce a significant change in the level of ATP, but since the technique did not allow fast changes in ATP to be observed, the possibility that there was breakdown of ATP followed by a rapid resynthesis cannot be ruled out.
The Role of Plasma Transferrin in Iron Absorption in the Rat
Authors: Morgan E. H.
Published: December 2014

The question of whether plasma transferrin acts as a carrier of iron from intestinal mucosal cells to the blood plasma was investigated in a series of experiments in the rat. By thoracic duct cannulation and collection of lymph during absorption it was confirmed that nearly all absorbed iron passes direcly to portal blood. The total rate of transcapillary exchange of transferrin and the rate of passage of plasma transferrin into the extravascular compartment of the intestinal mucosa were then measured in separate groups of rats. The rates of exchange were insufficient for transferrin to act as the carrier of iron at the rate at which it passes from intestinal cells to portal plasma after ingesting a dose of inorganic iron. Some specific binding of transferrin and cellular uptake of iron by intestinal mucosa was observed after the intravenous injection of transferrin labelled with 59Fe and 125I. It is concluded from these experiments that absorbed iron passes from intestinal cells to portal plasma largely in a low molecular weight form. The passage of plasma transferrin into the interstitial fluid of the intestinal mucosa and binding to mucosal cells probably functions primarily to supply iron to the cells and not to act as a carrier of iron from the cells.
Physical Fitness Training in Patients
Authors: Newell J. P. , Kappagoda C. T. , Linden R. J.
Published: December 2014

Patients recovering after heart valve surgery are not in an optimum state of ‘cardiorespiratory fitness’. To examine this proposition a controlled trial of physical training was undertaken in patients recovering from the replacement of a single heart valve.

Patients were allocated to a test or control group two weeks after operation. Each patient performed a submaximal exercise test at entry, and twelve and twenty‐four weeks after this test. The Canadian Air Force exercise programme was undertaken by the test group, while the control group continued normal activities for the twenty‐four weeks between the first and last exercise test. A regression line of submaximal heart rate on oxygen consumption was calculated from the data of each exercise test in each patient. Alterations in this line were used as an ‘index’ of changes in ‘cardiorespiratory fitness’.

The individual results showed a consistent improvement in ‘cardiorespiratory fitness’ over the first 12 weeks in both groups. Only patients in the test group continued to improve between 12 and 24 weeks. Thus the exercise programme modified the recovery of ‘cardiorespiratory fitness’ after operation.

A physical fitness rehabilitation programme may help these patients gain maximum benefit from corrective surgery.
Diuretic Effect of Intraventricular and Intravenous Infusions of Noradrenaline in Conscious Sheep
Authors: Beal A. M. , Bligh J.
Published: December 2014

Influsion of noradrenaline at rates between 32 160 nmol.min‐1 for 30 min into one lateral cerebra; ventricle of conscious sheep caused a diuresis which was accompanied by negative solute‐free water reabsorption and which lasted for 90 120 min. The range of noradrenaline infusion rates used reflects differences between individual animals in the rate of infusion necessary to cause diuresis. Intracerebroventricular (ICV) infusion of noradrenaline at half the diuretic rate caused no significant changes in urine flow. The diuresis induced by ICV noradrenaline infusion was prevented by concurrent ICV administration of the α‐adrenergic analgonist, phentolamine, but was not prevented by concurrent ICV administration of the β antagonist, propranolo, or by concurrent intravenous infusion of phentolamine. Intravenous infusion of naradrenaline at rates that were diuretic by ICV infusion caused a diuresis of approximately 30 min duration which coincided with the period of intravenous noradrenaline infusion. This diuresis was prevented by concurrent intravenous infusion of phentolamine. These results were interpreted as indicating that the higher rates of ICV infusion of noradrenaline caused the prolonged water diuresis by acting at a site in the brain and, thereby, inhibiting the release of endogenous vasopressin. ICV infusion of noradrenaline at all rates was followved by a reduction in mean arterial blood pressure and pulse pressure with variable changes in heart rate and by drepression of the rates of renal clearance of PAH. potassium and total solute.
STUDIES ON THE ABSORPTION OF THE PANCREATIC FUNCTION TEST PEPTIDE, N‐BENZOYL‐L‐TYROSYL‐p‐AMINOBENZOIC ACID, AND RELATED COMPOUNDS BY ISOLATED RAT SMALL INTESTINE
Authors: Gardner M. L. G. , Mitchell C. J.
Published: December 2014

The peptide, N‐benzoyl‐L‐tyrosyl‐p‐aminobenzoic acid, which is used in an oral test of pancreatic function, has been perfused through isolated rat small intestine in order to determine whether it can be absorbed across the intestine in intact form, and whether it is hydrolysed appreciably by intestinal enzymes. For comparison, transport of N‐benzoyl‐DL‐tyrosine, L‐tyrosine, L‐tyrosyl‐L‐leucine and p‐aminobenzoic acid has also been studied. Very small amounts of bound tyrosine (probably mainly intact peptide plus some benzoyl‐tyrosine) and of free p‐aminobenzoic acid crossed the intestine during perfusion with N‐benzoyl‐L‐tyrosyl‐p‐aminobenzoic acid. Adsorbed pancreatic enzymes were possibly responsible for the very small amount of hydrolysis of the peptide. However, no detectable free tyrosine crossed the intestine during perfusion with N‐benzoyl‐L‐tyrosyl‐p‐aminobenzoic acid or with N‐benzoyl‐DL‐tyrosine. In contrast, substantial quantities of free tyrosine crossed the intestine during perfusion with L‐tyrosine or with L‐tyrosyl‐L‐leucine. Net transport of tyrosine from L‐tyrosyl‐L‐leucine was less than that from equimolar free L‐tyrosine; no detectable intact L‐tyrosyl‐L‐leucine crossed the intestine. During perfusion with free p‐aminobenzoic acid the concentration in the serosal secretion apparently exceeded that in the lumen by a factor of 1·7; this suggests active transport of p‐aminobenzoic acid.
DYNAMIC REDISTRIBUTION OF CORONARY BLOOD FLOW IN THE DOG AS MEASURED BY A THERMISTOR TECHNIQUE
Authors: Kedem Joseph , Acad Bat‐Ami , Sonn Judith
Published: December 2014

The effect of heart rate upon the coronary blood supply to the right and left ventricles was studied in anaesthetized, open‐chest dogs. Indirect recording of coronary supply was obtained using thermistors placed locally on the surface or in the wall of the ventricles. The validity of the thermistor technique was examined in vivo as well as by using an in vitro laboratory model. Myocardial perfusion was also measured using electromagnetic flowmeters placed around the anterior descending and circumflex arteries, as well as the coronary sinus and Thebesian drainage. It was found that at heart rates lower than about 150/min, coronary perfusion to all areas increased equally as rate was elevated. At higher heart rates, coronary flow to the right ventricle continued to increase linearly with rate, whereas perfusion to the left ventricle either increased much less or declined. It is concluded that tachycardia causes coronary flow to be dynamically redistributed in favour of the right ventricle.
THE NATURE OF ATRIAL RECEPTORS RESPONSIBLE FOR THE INCREASE IN URINE FLOW CAUSED BY DISTENSION OF THE LEFT ATRIUM IN THE DOG
Authors: Sivananthan N. , Kappagoda C. T. , Linden R. J.
Published: December 2014

In dogs anaesthetized with α‐chloralose the effects of distension of a large balloon in the lumen of the left atrium on the discharge of action potentials in vagal fibres and on urine flow were studied with the cervical vagi cooled at 18 and 12 °C. Distension of the balloon in seven dogs resulted in an increase in urine flow. Cooling the cervical vagi to 18 °C reduced the response to 70% of that obtained at 37 °C, and at 12 °C the response was reduced to 28%. In a second group of dogs, the effect of distension of the balloon on atrial receptors which discharged into myelinated nerve fibres of the vagi, i.e. Paintal type A and type B receptors, was examined. The increase in the activity of these receptors was reduced to 68% when the vagus nerve was cooled to 18 °C and was reduced further to 25% at 12 °C. In a third group of dogs, the effect of distension of the balloon on receptors which discharged into non‐myelinated nerve fibres in the vagi was examined. Cooling of the cervical vagi also reduced the evoked increase in activity in these fibres; this reduction in activity occurred over a wider range of temperature, unlike the effect of cooling on the response in myelinated vagal fibres. It is concluded that the increase in urine flow caused by distension of a balloon in the left atrium is mediated solely by the Paintal‐type atrial receptors which discharge into the myelinated fibres in the vagi.
EFFECTS OF PREGNANCY ON THE FEBRILE RESPONSE IN SHEEP
Authors: Heap R. B. , Silver Ann , Walters D. E.
Published: December 2014

Pyrogens were injected into unshorn pregnant and non‐pregnant Soay and Clun Forest sheep and the effects on rectal temperature and thermoregulatory mechanisms monitored. Plasma concentrations of unconjugated oestrogens, progesterone and cortisol were measured in the sheep tested in late pregnancy. The effect of pyrogens was also examined in ovariectomized ewes treated with oestrogen and with oestrogen plus progesterone.

In contrast to reports of work on shorn sheep all sheep developed a fever even when close to term but the increase in peripheral vasomotor tone normally induced by pyrogens was attenuated in the pregnant Clun Forest ewes.

The hormone‐treated ovariectomized animals developed normal fevers and provided little indication of a possible relation between peripheral levels of ovarian steroids and the degree of fever.

The question of whether an endogenous antipyretic substance is present in pregnant sheep is discussed.
THE RESPONSES IN RENAL NERVES TO STIMULATION OF ATRIAL RECEPTORS, CAROTID SINUS BARORECEPTORS AND CAROTID CHEMORECEPTORS
Authors: Linden R. J. , Mary D. A. S. G. , Weatherill D.
Published: December 2014

The reflex reduction in activity in renal sympathetic nerves in response to distension of small balloons in the pulmonary vein‐atrial junctions was studied in dogs anaesthetized with chloralose; the carotid sinuses were isolated and perfused with blood. In the first group of dogs, the response to distension of the balloons was studied at different levels of carotid sinus pressure. In thirteen preparations of renal nerves in eight dogs the response was not significantly influenced when the mean carotid sinus pressure was changed from 9·5 kPa to 17·5 kPa, despite marked changes in control frequencies of activity in the nerves. In the second group of dogs, the response to distension of the balloons was studied when the carotid sinuses were perfused alternately with arterial and venous blood. In six preparations of renal nerves in five dogs the response was not significantly influenced when the blood perfusing the carotid sinuses was changed, despite marked changes in control frequencies of activity in the nerves. In a third group of dogs, the reflex reduction in activity in renal nerves in response to a step increase in pressure in one carotid sinus was examined at different levels of pressure in the contralateral carotid sinus. In six preparations of renal nerves in five dogs the response to an increase in pressure in one carotid sinus was significantly reduced when the mean pressure in the contralateral sinus was changed from 8·7 kPa to 17·1 kPa. It is concluded that there is no interaction between the projections of atrial receptors and carotid sinus baroreceptors or carotid chemoreceptors in their convergence on the same efferent renal neurones.
THE SHORT‐LATENCY RESPIRATORY RESPONSE TO SUDDEN WITHDRAWAL OF HYPERCAPNIA AND HYPOXIA IN MAN
Authors: Drysdale D. B. , Jensen J. I. , Cunningham D. J. C.
Published: December 2014

Five healthy young male subjects were maintained in a state of mild asphyxia (PA,CO2 ∼ 45 torr, 6·0 kPa, PA,O2 ∼ 50 torr, 6·6 kPa), i.e. with moderately strong drives from both arterial and intracranial chemoreceptors. VT, TT and TI were recorded and V and TE derived breath by breath. The arterial chemoreceptor component was briefly and abruptly reduced, perhaps silenced, by two separate procedures, each repeated twenty‐four times on each subject: B, removal of hypercapnia (two breaths hypoxia with PI,CO2 = 0 through a separate inspiratory line) and C, removal of asphyxia (two breaths O2). In control tests, A, the maintenance mixture was replaced by an identical mixture, using an identical manipulation. For each subject means of B and C were compared with means of A and with each other. Quick reflex changes (first three breaths) in V, VT and TE in tests B were not appreciably different from those in tests C in any subject; changes in TI were minimal in all. Thus removal of only the hypercapnic component of the arterial chemoreflex drive appears to be as efficient as the removal of both components simultaneously.
IN VIVO MORPHOLOGY AND ULTRASTRUCTURE OF THYROID AUTOGRAFTS IN RABBIT EAR CHAMBERS
Authors: Narayan K. , Cliff W. J.
Published: December 2014

Partial thyroidectomies were performed in half‐lop rabbits. Small pieces of thyroid tissue were grafted into fully healed Sandison‐Clark rabbit ear chambers. Thyroid grafts were observed directly through the compound microscope and sequential observations were recorded on photographic films and video tapes, with grafts remaining undisturbed within their vascular bed. Circulation within grafts was established within 3–5 d post‐operatively, and between the second and fourth week pulsatile lymphatics loaded with lymphocytes could be observed within the grafts. Moreover, initial cellular infiltration, epithelial cell necrosis and regeneration have been recorded. Clear spaces or droplets observed within the colloid in vivo are considered to correspond to histological features long considered to be artefacts. This technique allows a non‐intrusive approach to the study of the thyroid gland and thus can be used in studies of in vivo thyroid physiology, pharmacology, pathology and therapy.
ROLE OF ANGIOTENSIN II AND BRANDYKININ IN THE DIURESIS CAUSED BY STIMULATION OF ATRIAL RECEPTORS
Authors: Knapp M. F. , Linden R. J. , Mary D. A. S. G. , Pearson M. J.
Published: December 2014

M. F. KNAPP, R. J. LINDEN, D. A. S. G. MARY & M. J. PEARSON

Quarterly Journal of Experimental Physiology (1980) 65, 335–347.

The paper is reprinted in full because neither of its tables appeared in the original version. When quoting this paper as a reference the original citation (as above) should be used.
RESPIRATORY INHIBITION FROM CHICKEN INTRAPULMONARY CHEMORECEPTORS REDUCED BY INCREASING RATE OF REPETITIVE PCO2 CHANGES
Authors: Barker Margaret R. , Burger Ray E. , Nye Piers C. G.
Published: December 2014

There is no functional residual capacity in the avian lung, so during inspiration the PCO2 of the gas entering the exchange region abruptly changes from its maximum, the dead space PCO2, to its minimum, the inspired PCO2. Dynamic responses of intrapulmonary chemoreceptors (i.p.c.s) to positive and negative going steps in PCO2 are asymmetrical and have maxima occurring at times comparable to inspiratory duration. Thus, the respiratory inhibition that i.p.c.s produce could depend on respiratory frequency. We tested this hypothesis by changing intrapulmonary PCO2 repetitively between 7 and 42 torr in the non‐perfused left lungs of eight unidirectionally ventilated thoracotomized chickens. Right intrapulmonary and arterial PCO2 were kept constant. Respiratory movements were calibrated in terms of steady state intrapulmonary PCO2 levels. At PCO2 repetition rates comparable to normal respiratory frequency, respiratory movements were equal to those expected for an intrapulmonary PCO2 2‐3 torr lower than the average of the two PCO2 levels used. This difference increased linearly as the logarithm of the repetition rate decreased. We conclude that respiratory inhibition by i.p.c.s is inversely related to respiratory rate as well as to average intrapulmonary PCO2 levels. Because respiratory frequency itself is negatively related to i.p.c. discharge frequency, i.p.c.s may provide control over respiratory frequency even if average PCO2 levels do not change.
THE TERMINATIONS AND SECONDARY PROJECTIONS OF MYELINATED AND NON‐MYELINATED FIBRES OF THE AORTIC NERVE IN THE CAT
Authors: Donoghue S. , Fox R. E. , Kidd C. , McWilliam P. N.
Published: December 2014

In anaesthetized cats the projection of myelinated and non‐myelinated afferent fibres of the aortic nerve to the brain stem was studied by recording antidromic potentials evoked in the nerve by electrical stimulation of the medulla oblongata. Probable sites of termination of both myelinated and non‐myelinated afferent fibres were found to be in the ipsilateral medial lateral subnucleus of the nucleus tractus solitarius, the ipsilateral area postrema, the commissural nucleus and the contralateral nucleus tractus solitarius about the level of the obex. No evidence for a projection of primary afferent fibres in the aortic nerve to the medial reticular formation was found. In a second series of experiments the aortic nerve was electrically stimulated and extracellular recordings were made from neurones in the medulla activated by afferent fibres in this nerve. Neurones activated by myelinated afferent fibres were located in the nucleus tractus solitarius, dorsal vagal motor nucleus, commissural nucleus, area postrema and lateral reticular formation including nucleus ambiguus. Neurones activated by non‐myelinated afferent fibres were in or near the medial nucleus tractus solitarius, the area postrema, dorsal motor vagal nucleus and nuclus intercalatus. Few neurones appeared to be activated by both myelinated and non‐myelinated afferent fibres and they were located in the medial nucleus tractus solitarius and nucleus ambiguus.
SOME EFFECTS OF DIET ON THE MITOTIC INDEX AND THE CELL CYCLE OF THE RUMINAL EPITHELIUM OF SHEEP
Authors: Goodlad R. A.
Published: December 2014

The mitotic index of the ruminal epithelium increased rapidly when the diet of sheep was changed from one based on roughage to a concentrate‐based diet. After several days the mitotic index declined to a new level which was slightly higher than that observed initially. Autoradiography of sections of rumen epithelium was used to construct percent labelled mitoses curves, from which the duration of the phases of the cell cycle was determined. The duration of the cell cycle was about 24 hr but decreased to 17 hr when cell proliferation was stimulated by changing the diet of the sheep from roughage to concentrate. The decrease in cell cycle time was mainly the result of the decreased duration of the phase of DNA synthesis (S phase).

Data obtained from measurement of the cell cycle, together with the labelling index, were used to calculate the turnover times of the basal cell layer, and to estimate ‘turnover’ times for the entire epithelium. The mean turnover time for the epithelium was 16·5 days when sheep were fed a roughage‐based diet, 10·9 days when fed a concentrate basal diet and 4·3 days when the sheep were in transition between the roughage and the concentrate diets.
FLUID AND ELECTROLYTE EXCRETION IN SHEEP: COMPARISON OF THE EFFECT OF REDUCED FOOD AND WATER INTAKE WITH OESTRUS
Authors: Michell A. R.
Published: December 2014

Food and water intake were restricted by 29% for 48 h in ovariectomized ewes, to see whether such changes could cause a pattern of water and electrolyte excretion similar to that observed during the oestrous cycle. The closest resemblance appeared in the effect on water balance and there was also a rise in sodium excretion, as at oestrus. Restriction of intake failed to duplicate the marked sodium retention or, more particularly, the persistent potassium retention which follow natural oestrus. Restriction of food alone produced changes less similar to those seen at oestrus, mainly because this treatment caused a large increase in urine output. The similarity between the effects of restriction and ‘fasting natriuresis’ is discussed, with particular reference to the mildness of the stimulus in these experiments. Indications that the gut may be as important as the kidney in the regulation of salt and water balance are discussed in relation to other herbivores and to man.
DEGENERATION SECRETION OF AMYLASE FROM THE PAROTID GLAND OF THE RAT
Authors: Asking B. , Emmelin N. , Gjörstrup P.
Published: December 2014

In anaesthetized rats the parotid saliva secreted during degeneration of the auriculo‐temporal nerve contains amylase in fairly constant concentration, the amylase output varying with the secretory rate. The amount of amylase was not reduced by adrenoceptor blocking agents; it was increased by sympathectomy carried out one week in advance. A sympathetic degeneration secretion of amylase could also be demonstrated while the post‐ganglionic sympathetic nerves were degenerating; a simultaneous parasympathetic degeneration secretion provided the salivary flow needed for the transport of the amylase.
SODIUM MOVEMENTS ACROSS THE VASCULARLY PERFUSED ANURAN SMALL INTESTINE AND COLON
Authors: Parsons D. S. , Wade S. A.
Published: December 2014

Values of unidirectional Na fluxes measured across the vascularly perfused small intestine of three anuran species are higher than those found in other preparations in vitro. In Rana ridibunda and R. pipiens no net movement of Na across the small intestine can be detected. In contrast, the unidirectional fluxes of Na across the colon of R. ridibunda and R. pipiens are lower than across the small intestine and a significant net absorption is found. Apparent loading and unloading pools for Na within the small intestine, as measured with tracer Na under standard experimental conditions, consist largely of extracellular Na presumably within the bulk phase of the lumen. The size of these pools can be greatly reduced by the rapid addition to or removal from the lumen of tracer. The loading pool appears to occupy not more than about 9% of the total tissue water, equivalent to about 20% of the extracellular water of the tissue. The washout of tracer Na from preloaded small intestine into the vascular bed is bi‐exponential and appears from a pool, or pools, of apparent greater size than that of the loading pool. The results show that Na can move very rapidly across the small intestine and suggest that a high proportion of this movement occurs possibly via paracellular shunt pathways.
RENAL RESPONSE TO HYPOTONIC SALINE LOAD IN FETAL AND NEW‐BORN PIGS
Authors: Alt J. M. , Colenbrander B. , MacDonald A. A. , Forsling M. L.
Published: December 2014

Kidney function has been studied in pig fetuses (105–109 d of gestation) and neonates (5–7 d old). Urine was collected by catheterization of the ureter. Inulin clearance, the excretion of electrolytes and the osmolality of urine and plasma were measured. In addition the response of the fetal neurohypophysis and fetal and neonatal kidney to a reduction of plasma osmolality was studied. The results show that the inulin clearance increases rapidly in the perinatal period, at a rate greater than would be expected from the gain in body weight.

The re‐absorption of Na and K is well developed. The fractional sodium excretion in fetuses is 2% and is 0·1% in the new‐borns. The urine osmolality is high, probably due to high plasma lysine vasopressin levels persisting throughout the experiment. The infusion of hypotonic saline results in a significant decrease of plasma osmolality but only three out of nineteen animals showed an increase in urine flow. Although lysine vasopressin concentrations fell in some animals the urine stayed hyperosmotic as compared with plasma. The results show that fetuses and neonates may react to volume load but in the conditions of these experiments the regulation of plasma osmolality was inadequate.
PERMEABILITY OF CANINE SUBMANDIBULAR GLANDS TO BLOOD‐BORNE HORSERADISH PEROXIDASE DURING PARASYMPATHETIC SECRETION
Authors: Garrett J. R. , Klinger A. H. , Parsons P. A.
Published: December 2014

Potential permeability pathways exist between central acinar cells in submandibular glands of dogs and they are large enough to allow the passage of molecules of horseradish peroxidase (HRP) under certain conditions.

During gentle submandibular secretion caused by parasympathetic nerve stimulation detectable amounts of HRP passed into the saliva as long as the concentration of HRP in the blood reaching the gland was high enough. Morphological results indicated that the passage was mainly via leaky junctions between acinar cells. It is likely that this movement was by passive permeation because it required a high concentration gradient, was slow to occur and gradually reached a peak; the actual amounts to reach the saliva under physiological conditions were small and depended on the effective concentration of HRP reaching the gland.

A satisfactory reproducible secretory regime has been developed, using short periods of stimulation alternating with rest pauses. Using these conditions gradually increasing amounts of HRP reached the saliva and first samples of saliva during each stimulation period contained more HRP than subsequent samples from the same stimulation period. It is possible that contraction of myoepithelial cells, at the outset of each stimulation period, contributed to this increased movement by acting on HRP‐containing fluid in spaces between themselves and the acinar cells, thereby causing an increased filtration pressure to be exerted on underlying tight junctions.
PAROTID DEGENERATION SECRETION OF AMYLASE IN VITRO IN THE RAT FOLLOWING SYMPATHECTOMY
Authors: Asking B. , Emmelin N. , Gjörstrup P. , Pärsson H.
Published: December 2014

After extirpation of the superior cervical ganglion in the rat a degeneration secretion of amylase occurs in an in vitro preparation of the parotid gland. It can be detected about 14 h after the sympathectomy, reaches a maximum after about 17 h and then slowly subsides. It is abolished by atenolol, but not by dihydroergotamine or atropine, nor by tetrodotoxin. From this it is concluded that the phenomenon is due to an action mainly on β1‐adrenoceptors exerted by noradrenaline, which is released from the degenerating sympathetic nerves at the neuro‐glandular junctions, independently of propagated nerve impulses.
THE TIMING AND POSSIBLE MECHANISMS OF CERVICAL OPENING IN THE OESTROUS RAT
Authors: Foulkes A. , Bradshaw Jane M. C. , Porter D. G.
Published: December 2014

The time that the retention of luminal fluid begins and its release from the uterus in pro‐oestrous rats was determined precisely using a dye injection technique. Oestradiol was found to cause dye retention in ovariectomized rats when provided continuously from an implant of 5 mg. Injections of 0·5 µg/d x 4 were ineffective. Administration of progesterone to rats bearing implants of oestrogen interfered with the ability of the uterus to retain dye. Treatment with relaxin for 28 h prevented retention of dye in pro‐oestrous rats whereas treatment at the time of dye injection was without effect. Mechanical stimulation of the cervix did not cause loss of injected dye. It is suggested that the mechanisms of opening of the cervix at coitus and at the end of oestrus may differ.
BLOOD VOLUME IN THE PREGNANT RABBIT
Authors: Prince Heather
Published: December 2014

Red cell and plasma volumes were measured using 51Cr‐labelled red cells and 125I‐labelled HSA respectively, in seventeen pregnant rabbits at 28‐29 days of pregnancy, and fifteen non‐pregnant rabbits weight‐matched with the pregnant rabbits before mating. Red cell volume in the pregnant group (20·0 ± 2·7 ml.kg‐1; mean ± S.D.), was greater than in the control rabbits (18·0 ± 2·0 ml.kg‐1; P 〈 0·05); plasma volumes (39·0 ± 4·5 and 37·3 ± 4·4 ml.kg‐1 respectively) were not statistically different. Blood volume was derived from the sum of independently measured red cell and plasma volumes. That of the pregnant group (59·0 ± 5·3 ml.kg‐1) was just significantly greater than that of the control rabbits (55·3 ± 5·3 ml.kg‐1; P 〈 0·05). When the volume of distribution of the labels was corrected, by subtracting fetal weight from maternal body weight, the red cell, plasma and blood volumes were all significantly greater in the pregnant rabbits (P 〈 0·02). Although the large vessel haematocrit of the pregnant group (41·6 ± 4·4%) exceeded that of the non‐pregnant group (38·7 ± 2·6%; P 〈 0·05), there was no significant difference in whole body haematocrit or Fcells (the ratio of whole body to large vessel haematocrit) between the two groups of rabbits.
THE EFFECTS OF AN ANGIOTENSIN BLOCKER (SARALASIN) ON KIDNEY FUNCTION IN DEHYDRATED SHEEP
Authors: Yesberg Nancy E. , Henderson Myrna , Wilson Kathleen , Law Sandra , Cross R. B.
Published: December 2014

Saralasin, an angiotensin II analogue and receptor blocker, was infused at 7 and 15 µg.min‐1 into dehydrated conscious Merino ewes. This caused mean arterial blood pressure, cardiac output, heart rate and renal vascular resistance to fall, and central venous pressure to rise. Renal plasma flow was unaffected but there were significant reductions in glomerular filtration rate, filtration fraction, urine flow, sodium and potassium excretion, solute clearance and solute‐free water reabsorption. It is suggested that saralasin produced these effects by inhibiting endogenous angiotensin II activity, and in particular by causing a reduction in renal post‐glomerular resistance. This in turn caused a fall in glomerular filtration rate and filtration fraction. While saralasin might have had effects on renal tubular function and perhaps on vasopressin secretion, the observed effects on renal function can be explained by the decrease in glomerular filtration rate and filtration fraction.
PHYSIOLOGICAL SIGNIFICANCE OF THE CONTRACTIONS OF THE RABBIT PROXIMAL COLON
Authors: Ehrlein Hans‐Jörg , Reich Helmut , Schwinger Martina
Published: December 2014

In humans and in carnivores the motor activity of the colon was separated into various types based on records of the intraluminal pressure. However, little is actually known about the physiological significance of the various pressure waves. The aim of the present investigation was to clarify the basic pattern of colonic motility in a herbivorous species. Motility of the proximal colon was studied by strain gauge transducer records combined either with fluoroscopy or by direct visual observation in conscious and anaesthetized rabbits. In the proximal colon three types of contractions were found: (1) high frequency repetitive contractions, (2) low frequency rises of the base line, and (3) monophasic progressive waves. The frequency of the repetitive contractions was 13·8 contractions/min at the oral site and 16·3 contractions/min at the aboral site of the proximal colon. The mean duration of the repetitive contractions was 3·2 ± 1 s. They coincided with orally migrating (1‐2 mm/s) shallow annular constrictions which represented haustral activity. The low frequency rises of the base line (mean duration 131 ± 47 s) were associated with aborally migrating (7 mm/min) deep annular constrictions representing segmental activity. The monophasic progressive waves represented peristaltic contractions. The mean durations of the monophasic waves were 5·5 ± 1·2 s (period of hard faeces formation), and 9·7 ± 2·8 s (period of soft faeces formation), the average rates of progression were 3·2 ± 1·2 cm/s (period of hard faeces production), and 1·3 ± 0·6 cm/s (period of soft faeces production). The results proved that the colonic motility of rabbits consisted of a complex motor pattern. The present classification was similar but not identical with that described in carnivores and man. Further comparative studies on other mammals are necessary to decide whether the motor activity of the colon is comparable between various species.
ANOREXIA AND ANTAGONISM OF THIAMIN UTILIZATION IN POULTRY TREATED WITH FURAZOLIDONE
Authors: Ali B. H. , Bartlet A. L.
Published: December 2014

Furazolidone (0·04% w/w in the feed, 10 days) reduced the feed intake and growth in 9 week old chickens, and increased the amount of 5‐hydroxytryptamine (5‐HT) in the brain. The drug also increased the stimulation of transketolase activity by thiamin pyrophosphate (TPP) in lysed blood cells (TPP effect), and the concentrations of pyruvate and lactate in the blood. Experiments with pair‐fed birds showed that the reduction in feed intake in furazolidone‐treated chickens could account for the reduced growth. The drug also produced anorexia in ducklings and turkey poults. In chickens, the anorectic action of furazolidone was unaffected by methergoline (1 mg/kg, twice daily, I.M.), and in ducklings furazolidone did not consistently produce anorexia, although it always inhibited monoamine oxidase (MAO) activity in the brain. These observations suggest that the anorectic action of the drug was not tryptaminergic in nature. The increase in the TPP effect found in preparations from furazolidone‐treated chickens was absent in preparations from pair‐fed birds on unmedicated feed. Thus the TPP effect could be used as an indicator of the effect of the drug on the thiamin status of chickens. However, the increase in the concentrations of pyruvate and lactate in blood was found both in furazolidone‐treated birds and pair‐fed birds on unmedicated feed, showing that they were attributable to the reduction in feed intake. The TPP effect in furazolidone‐treated chickens, 14·49 ± 2·33% (n = 10), was sufficient to suggest a mild deficiency of thiamin pyrophosphate. Thiamin, given at a dosage above the requirement of the vitamin for chickens, did not reduce the anorexia or the TPP effect in furazolidone‐treated birds, although it stimulated the feed intake and growth of birds on unmedicated feed. It is proposed that furazolidone antagonized the utilization of thiamin, perhaps by inhibiting its phosphorylation. Following the withdrawal of furazolidone, the TPP effect returned to the control value and the rate of growth of the birds increased and matched that of the controls. Thus the effect of the drug was reversible. Addition of furazolidone to the feed at a concentration of 0·01% w/w for 28 days did not produce anorexia in chickens or affect the amount of 5‐HT in the brain. Thus at this level, it is unlikely that the drug would produce adverse effects in poultry.
THE USE OF A MODIFIED BROMOSULPHTHALEIN EXCRETION TEST FOR THE MEASUREMENT OF HEPATIC BLOOD FLOW IN CALVES
Authors: Araya O. , Ford E. J. H.
Published: December 2014

Single intravenous injections of bromosulphthalein (BSP) were given to calves before and at intervals after the oral administration of 1000 metacercariae of Fasciola hepatica. The change in BSP concentration with time was analysed by computer to obtain the proportion of BSP extracted from plasma by hepatic cells (E) and the rate of hepatic blood flow (F). The increasing age of the normal calves during the 34 weeks of experiment had no significant effect on E or F. There was no significant effect of the duration of the fasciola lesion on E or F. When all tests on infected calves were compared as a group with tests on uninfected calves, there was a significant reduction in E(P 〈 0·05) and in F(P 〈 0·001) in the calves infected with F. hepatica. A survey of previously reported results suggests that sheep and cattle have a wide range of F values and that F is probably lower in 3‐month‐old calves than in adult cattle.
MEASUREMENTS OF ENDOMETRIAL BLOOD FLOW IN ANAESTHETIZED EWES BY XENON‐133 CLEARANCE AND MICROSPHERE TECHNIQUES
Authors: Fraser I. S. , Brown B. W. , Mattner P. E. , Hutton B. F.
Published: December 2014

In six anaesthetized, non‐pregnant ewes, uterine blood flow rates measured by monitoring the clearance of xenon (133Xe) from the lumen of the uterus were compared with estimates of endometrial and myometrial capillary blood flow obtained by the use of microspheres of 15 µm diameter (eleven comparisons).

On analysis, seven of the 133Xe clearance curves indicated the occurrence of both a fast and a slow compartment of flow with flow rates approximating to the rate of capillary blood flow in the caruncular and inter‐caruncular portions of the endometrium, respectively. In each of the remaining four curves which provided a single estimate of flow, the derived blood flow rate was similar to the rate of capillary blood flow in both the caruncular and inter‐caruncular portions of the endometrium. No relationship existed between myometrial capillary blood flow and the flow rates derived from the 133Xe clearance curves.
THE EFFECT OF CARBACHOL AND ISOPRENALINE ON CELL DIVISION IN THE EXOCRINE PANCREAS OF THE RAT
Authors: Carling R. C. J. , Templeton D.
Published: December 2014

The effect of muscarinic cholinergic receptor stimulation on pancreatic acinar cell division has been investigated. Muscarinic receptor stimulation, in addition to causing a 50% depletion of amylase in the pancreas after 4 h, resulted in a 400% increase in the incorporation of [6‐3H]thymidine 27 h after drug administration. This increase in incorporation was dose‐dependent. Autoradiography showed this increase to be due to an increased acinar cell labelling. Isoprenaline also increased the incorporation of [6‐3H]thymidine into the pancreas but did not reduce enzyme levels. However, with isoprenaline there was no increase in acinar cell labelling. The possibility of a relationship between secretion and hyperplasia of acinar cells in the rat pancreas is discussed.
EFFECTS OF FASTING AND GLUCAGON ON THE KINETICS OF ACTIVE HEXOSE ABSORPTION ACROSS THE RAT DISTAL ILEUM IN VIVO
Authors: Debnam E. S.
Published: December 2014

The effects of starvation for 1, 2 or 3 d and the administration of glucagon to fed rats on the kinetics of active glucose and galactose absorption across the distal ileum have been determined in vivo. Fasting caused reductions in ‘apparent Kt’ for glucose and galactose transport together with a decrease in Jmax for glucose but not galactose absorption. Treatment with glucagon produced decreases in Kt for the absorption of both hexoses and an increase in Jmax for glucose absorption. The Jmax for galactose uptake, however, was unaltered by glucagon administration. Villus size was unaltered by starvation of up to 3 d duration, but significantly decreased by glucagon treatment. The results suggest that chronically elevated plasma glucagon levels may be a factor in the change in kinetics of hexose absorption in the distal ileum evoked by fasting.
THE EFFECTS OF STIMULATION OF LEFT ATRIAL RECEPTORS ON EFFERENT VAGAL NERVES TO THE DOG HEART
Authors: Walters G. E. , Mary D. A. S. G. , Linden R. J.
Published: December 2014

There is a controversy as to whether the increase in heart rate in response to stimulation of atrial receptors is mediated solely by the sympathetic or by both the sympathetic and vagal nerves to the heart. In dogs anaesthetized with chloralose the activity in vagal efferent nerve fibres from the cardiac branches of the right vagus nerve was recorded. The effects of distension of small balloons at the right pulmonary vein‐atrial junctions on this activity was investigated. Distension of the small balloons caused an increase in heart rate in all dogs. Distension of the small balloons had no effect on vagal efferent fibres whether these were affected by carotid occlusion or not (seven dogs), or whether they were affected by changes in the pressure or nature of the blood perfusing the vascularly isolated carotid sinuses or not (nine dogs). It is concluded that the increase in heart rate seen in response to stimulation of left atrial receptors by distension of small balloons at the pulmonary vein‐atrial junctions does not involve vagal efferent nerves.
AN ELECTROPHYSIOLOGICAL ANALYSIS OF THE EFFECTS OF COOLING ON AUTONOMIC NEUROMUSCULAR TRANSMISSION IN THE GUINEA‐PIG VAS DEFERENS
Authors: Blakeley A. G. H. , Cunnane T. C.
Published: December 2014

The effects of cooling upon the excitatory junction potential (e.j.p.) and spontaneous e.j.p.s. in the guinea‐pig vas deferens have been studied. A series of strict criteria have been used to select ‘successful’ penetration of smooth muscle cells by the micro‐electrodes. Cooling the vas from 35 to 22°C has little effect on the membrane potential. The e.j.p. is increased in size by cooling from 5·1±0·2 mV, n = 120 at 35 °C to 15·9±0·5 mV, n = 29 at 22 °C. Facilitation is less marked at lower temperatures. The effects of cooling are not due to any effects under the electrodes used to stimulate the innervation of the vas. The frequency and size of spontaneous e.j.p.s. is reduced by cooling. The significance of these observations is discussed.
ABSORPTION OF INTACT PEPTIDES: STUDIES ON TRANSPORT OF PROTEIN DIGESTS AND DIPEPTIDES ACROSS RAT SMALL INTESTINE IN VITRO
Authors: Gardner Michael L. G.
Published: December 2014

Passage of intact peptides across isolated rat small intestine has been studied during luminal perfusion with partial digests of proteins or with dipeptides. Significant passage of intact peptide does occur, the amount depending upon the luminal concentration. It probably reflects the ‘digestibility’ of the protein or protein digest. Previous studies are discussed and, although intact peptide transport is probably not of major nutritional importance, it is suggested that the pathophysiological significance of this process and of peptidaemia merits further attention.
EXACERBATION OF THE CALCIUM PARADOX WITH EXOGENOUS ADENOSINE TRIPHOSPHATE IN ISOLATED WORKING RAT HEART
Authors: Clemens M. G. , Forrester T.
Published: December 2014

The deleterious effect of calcium withdrawal and restoration on cardiac cell membranes (‘Ca‐paradox’) was studied using isolated, working rat heart. The optical density of the coronary sinus effluent was measured at 260 nm wavelength. The efflux of A260 material upon restoration of calcium was proportional to the duration of calcium‐free perfusion, indicating graded membranous injury. When ATP, 10‐6 to 10‐4 M, was added to the calcium‐free perfusate for 30 s of calcium‐free perfusion, release of A260 material increased as a logarithmic function of exogenous ATP concentration. That this exacerbating effect is produced by such low concentrations relative to intracellular amounts indicates an action of ATP on the membrane surface. It is suggested that exogenous ATP enhances calcium entry into the cell, thus contributing to calcium influx through membranes already rendered abnormally permeable from the ‘Ca‐paradox’ mechanism.