bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Starvation on Cardiovascular Function (including the Mammary Circulation) and Water Balance in Pregnant Goats
Authors: Chaiyabutr N. , Faulkner Anne , Peaker M.
Published: December 2014

In conscious goats, starved for 48 hr, in mid‐pregnancy (70 days) cardiac output and blood volume decreased; total peripheral resistance increased; heart rate, stroke volume, blood pressure, mammary blood flow and mammary resistance were not significantly affected. In late pregancy (132 days) cardiac output, heart rate, blood volume and mammary blood flow fell; peripheral resistance increased; stroke volume and blood pressure were not significantly affected. In mid‐pregnancy, water consumption fell and the animals entered a stage of negative sensible water balance which persisted for both days of starvation. A similar change was obtained on the first day in late‐pregnant goats, but on the second day water consumption increased and positive water balance was restored.

Cardiac output, heart rate, blood volume and mammary blood flow were higher in fed late‐pregnant than in fed mid‐pregnant goats, total peripheral resistance was lower while there were no significant changes in stroke volume or blood pressure. Indications of correlations between litter size and cardiac function were obtained.

The results are compared with previous studies on the effects of starvation in lactating animals and are discussed in relation to the control of cardiac function and mammary blood flow in pregancy and lactation.
An Effect of Hypothalamic Stimulation on Cardiac Output in the Rabbit
Authors: Evans M. H.
Published: December 2014

Electrical stimulation of a discrete region of the rabbit brainstem, in the lateral hypothalamic area near the mammillothalamic tract, caused an increase in arterial blood pressure accompanied by bradycardia in anaesthetized animals. The cardiac output, measured by a thermodilution technique, was found to fall when the stimulus strength was great enough to evoke strong bradycardia. Threshold current for this effect varied in different animals in the range: 50–350µA (1 msec pulse duration and 60 pulses/sec repetition rate). Bilateral vagotomy eliminated almost all the negative chronotropic effects of hypothalamic stimulation, but reversed only about one‐third of the fall in cardiac output during strong stimulation. It is suggested that negative chronotropic, and possibly inotropic, vagal effects on the heart play a relatively minor role in reducing cardiac output. The major factor in causing output to fall may be left ventricular overload during the widespread peripheral vasoconstriction that accompanies stimulation of this region of the rabbit hypothalamus.
Effects of Dihydro‐β‐Erythroidine on the Cat Carotid Chemoreceptors
Authors: McQueen D. S.
Published: December 2014

The effects of the nicotinic‐blocking drug dihydro‐β‐erythroidine (DHE) on chemoreceptor responses to physiological and pharmacological stimuli have been examined in pentobarbitone anaesthetized cats in which chemoreceptor discharge was recorded from the peripheral end of a sectioned sinus nerve. High doses of DHE greatly reduced the excitatory action of ACh on the chemoreceptors and caused a reduction in responses to CO2. The effect of NaCN was not much affected, even though the high doses of DHE can reasonably be expected to have penetrated the carotid body tissues very effectively. Low doses of DHE reduced the excitatory action of ACh but potentiated responses to NaCN and CO2. findings which are compatible with endogenous ACh exerting an inhibitory influence on the chemoreceptors.
Axon Reflex in Ocular Injury: Sensory Mediation of the Response of the Rabbit Eye to Laser Irradiation of the Iris
Authors: Butler J. M. , Unger W. G. , Cole D. F.
Published: December 2014

Laser irradiation of the rabbit iris produces an injury response consisting of prolonged miosis, uveal vasodilation and a transient rise of intraocular pressure (IOP) accompanied by a breakdown of the blood‐aqueous barrier. This response has hitherto been attributed partly to prostaglandin (PG) mediation and partly to mediation by a non‐cholinergic nervous pathway thought to be sensory in function. Responses of the rabbit eye to laser irritation were examined at specified intervals after diathermic coagulation of the epigasserian nerve tract. Both the intensity of the pupillary constriction and the increase in IOP were almost unaltered at 90 minutes but progressively decreased until at 4 days there was essentially no response to high energy laser irradiation in the denervated eye. It was evident that manifestation of the response is largely dependent upon the presence of intact and functional sensory nerves, and it is proposed that endogenous PGs exert some, if not all of their effects via sensory nerve endings. It is suggested that those terminals which are directly stimulated, whether by laser irradiation or by PGs formed during the injury, release some mediator to cause pupillary constriction. From these terminals impulses pass orthodromically and antidromically by axon reflex to release further mediator from terminals in the region of the ciliary vessels or the major arterial circle. In this way the response is propagated and augmented.
An Electrophysiological Study of the Effects of Ionophore A23187 on Nauphoeta Salivary Glands
Authors: Mitchell Mary R. , Martin A. R.
Published: December 2014

The ionophore A23187 produces a hyperpolarization of cockroaclch salivary gland cells in the presence or absence of added calcium ions. The effect is greater and more prolonged in the presence of calcium and is dependent on the external potassium ion concentration.

It is proposed that the ionophore can increase the intracellular calcium ion concentration by an increase in influx from the external medium or by mobilization of intracellular calcium stores and that this results in an increase in the potassium permeability, thus producing a hyperpolarization.
THE POSSIBLE INVOLVEMENT OF ASPARTATE RECEPTORS IN CENTRAL THERMOREGULATION IN THE SHEEP
Authors: Silver Ann
Published: December 2014

Experiments have been done to investigate the possible existence of aspartate receptors on the hypothalamic pathways which control thermoregulation in the sheep. The effect of intracerebroventricular (I.C.V.) injections of the excitatory amino acid receptor blocker DL‐α,ε‐aminopimelic acid (DAPA) on thermoregulatory effector mechanisms and rectal temperature (Tre) has been examined in sheep at different ambient temperatures. At low ambient temperatures, DAPA causes a decrease in heat production and conservation and a fall in Tre. At higher ambient temperatures there is some evidence for a decrease in heat loss and a rise in Tre. DAPA attenuated the stimulatory effect on heat‐production/conservation mechanisms produced by I.C.V. injections of L‐aspartate but was without effect on the thermoregulatory responses to I.C.V. injections of carbachol and 5‐hydroxytryptamine or I. V. injections of a pyrogen. I.C.V. injections of the L‐aspartate analogue, N‐methyl‐DL‐aspartate produced similar effects to L‐aspartate. The results provide support for the suggestion that aspartate receptors may be present on the hypothalamic pathway between cold‐sensors and heat‐production/conservation effectors. Evidence for the existence of such receptors on the pathway between warm‐sensors and heat‐loss effectors remains scant.
THE EFFECTS OF PROGESTERONE ON GLUCOSE AND LACTATE METABOLISM IN OVARIECTOMIZED SHEEP
Authors: Samad A. R. , Ford E. J. H.
Published: December 2014

In nine samples from four ovariectomized sheep the mean plasma concentration of progesterone was 0·19 ± 0·04 ng/ml. After the subcutaneous implantation of 3 x 375 mg of progesterone in silicone rubber the concentration rose to 3·8 ± 0·51 ng/ml at 48 h and fell steadily to 1·5 ng/ml at 21 days. Removal of the implants caused a reduction to pre‐implantation values by 48 h. The increased concentration of circulating progesterone after implantation had no significant effect on the concentration of glucose in plasma, its total entry rate, irreversible loss or on plasma lactate concentration. Glucose recycling increased from 0·13 ± 0·05 to 0·38 ± 0·12 mg min‐1 kg‐1 (P 〈 0·05). Lactate entry rate fell from 1·68 ± 0·16 to 1·12 ± 0·10 mg min‐1 kg‐1 (P 〈 0·02). The total net formation of lactate from glucose fell from 0·56 ± 0·05 to 0·41 ± 0·08 mg min‐1 kg‐1 (P 〈 0·05). The production of lactate from non‐glucose substrates fell from 1·15 ± 0·11 to 0·70 ± 0·04 mg min‐1 kg‐1 (P 〈 0·02). The utilization of lactate for purposes other than glucose synthesis fell from 1·50 ± 0·14 to 0·97 ± 0·09 mg min‐1 kg‐1 (P 〈 0·05). The results support the view that progesterone produces an increase in glucose recycling by pathways involving compounds other than lactate.
PHYSIOLOGICAL CHARACTERISTICS OF LOW THRESHOLD MECHANORECEPTOR AFFERENT UNITS INNERVATING FROG SKIN
Authors: Ogawa Hisashi , Morimoto Katsushi , Yamashita Yoshiro
Published: December 2014

A total of ninety‐three mechanoreceptor afferent units with fast conducting axons in the sciatic nerve innervating the plantar and lateral surface of the hind foot were isolated for electrophysiological recording in anaesthetized frogs (Rana catesbeiana). Sixty‐three rapidly adapting (RA) units and thirty slowly adapting (SA) units were differentiated from each other mainly on the presence of an ‘off’ response and a slope‐locked ‘on’ response to ramp stimulation in RA units and on the persistence of discharges of the SA units during steady pressure on the receptive field. RA units were subdivided into two subgroups; RA type I units and RA type II units. The RA type I units had small well‐demarcated receptive fields in which the unit was uniformly sensitive, and low indentation amplitude and velocity thresholds. The RA type II units had receptive fields consisting of several sensitive spots, associated with skin warts in the warty skin, high indentation thresholds, and the fastest conduction velocities (mean 19·9 ± 4·4 m/sec) among the three groups of the units studied. RA type I units showed U‐shaped tuning curves with a best tuning frequency at around 2 Hz, while tuning curves of SA units were flat from 0·1 (the lowest frequency examined) to 1 Hz. RA type II units could only follow the first cycle of continuous sinusoidal stimulation at any frequency. The relation between the indentation velocity and amplitude of the ramp and the spike discharges was analysed quantitatively.
THE INFLUENCE OF HIGH AND LOW SODIUM INTAKE ON BLOOD VOLUME IN THE DOG
Authors: Gupta B. N. , Linden R. J. , Mary D. A. S. G. , Weatherill D.
Published: December 2014

Plasma volume and blood volume were measured using T‐1824 in two groups of dogs which were kept on a diet differing only in its content of sodium chloride for periods exceeding six weeks. The group on low sodium intake received 0·55 mmol Na+.kg‐1.day‐1 and the group on high sodium intake received 12·4 mmol Na+.kg‐1.day‐1. Both plasma and blood volumes were distinctly greater in the group on high sodium intake than those in the group on low sodium intake, and there was no difference in the haematocrit between the two groups of dogs. It is concluded that a greater plasma volume and red cell volume resulted from high sodium intake than from low sodium intake.
THE ROLE OF RENAL NERVES IN THE DIURESIS AND NATRIURESIS CAUSED BY STIMULATION OF ATRIAL RECEPTORS
Authors: Sreeharan N. , Kappagoda C. T. , Linden R. J.
Published: December 2014

The diuretic response to stimulation of left atrial receptors by distending balloons located either at the pulmonary vein‐left atrial junctions or in the body of the left atrium, was studied in anaesthetized dogs in which one kidney had been surgically denervated. In these dogs diuretic and natriuretic responses to stimulation of atrial receptors were obtained in the denervated and the intact kidney; both responses were significantly greater in the intact kidney than in the denervated kidney. In the denervated kidney the natriuretic response showed a significant correlation to increases in heart rate resulting from stimulation of atrial receptors. It is concluded that the renal nerves contribute significantly to the increases in urine flow and sodium excretion in response to stimulation of atrial receptors. In the denervated kidney, the diuresis appeared to be mediated by a humoral mechanism and the natriuresis was associated with concomitant increases in heart rate.
ACTIVE TRANSPORT OF SALICYLATE BY RAT JEJUNUM
Authors: Fisher R. B.
Published: December 2014

Using an improved segmented flow technique the uptake of salicylate in low concentration (1–3 mM) by rat jejunum is found to be steady for ca. 30 min, and is proportional to lumen concentration. At higher lumen concentrations (6–8 mM) the rate of uptake falls from the beginning to very low levels. At low lumen concentrations the tissue fluid concentration rises to approximately three times the lumen concentration without significant effect on the uptake rate. This rise is an exponential function of the net water transport across the intestinal wall. The rate constant is of the same order of magnitude as those found earlier for equilibration of tissue fluid with glucose and wash‐out of protein from the tissue fluid. The uptake of salicylate is inhibited irreversibly by 2,4‐dinitrophenol (2–4 x 10‐5 M).
THE EFFECTS OF AGE ON SPATIAL FREQUENCY PERCEPTION IN HUMAN SUBJECTS
Authors: McGrath Clare , Morrison J. D.
Published: December 2014

Visual performance was measured in sixty‐six subjects aged from 5 to 94 years. The curve of contrast sensitivity against spatial frequency was obtained for each subject. This curve had a peak contrast sensitivity in the 2–6 c/deg (cycles/degree) range with the fall‐offs to either side of the peak described, on a double logarithmic plot, by straight lines. With advancing age, the position of the peak sensitivity remained unchanged but there was an overall decrease in contrast sensitivity. The highest spatial frequency which could be perceived remained constant up to 50 years, thereafter it fell with increasing age. The slope of the low frequency straight line remained unchanged while that of the high frequency straight line fell with increasing age, i.e. the loss of contrast sensitivity was greater for middle range spatial frequencies than for higher spatial frequencies. The possible site of these changes, i.e. the optics of the eye, the retina/brain or higher decision making centres, is discussed.
RESPIRATORY MODULATION BY VAGAL AFFERENTS IN PIGS
Authors: Clement M. G. , Aguggini G. , Miserocchi G.
Published: December 2014

We have studied the role of pulmonary vagal afferents and baroreceptors of the aortic arch on control of breathing in anaesthetized pigs. As in other species (dogs, cats and rabbits) the depth and rate of breathing was found to be controlled by a volume‐related vagal feed‐back loop from pulmonary stretch receptors. Rapid shallow breathing following histamine aerosol and phenyldiguanide I.V. (which are likely to stimulate pulmonary vagal iritant and J receptors) occurred through a decrease in the activation threshold of the inspiratory cut‐off mechanism without altering the matching of inspiratory to expiratory time. These results are also similar to those found in cats and rabbits. Histamine caused an increase in pulmonary resistance and a decrease in compliance: these effects were partially vagally mediated and partially due to a direct stimulation of smooth muscles by the drug. It seems, from relating the respiratory to the vascular systemic effect of histamine administration, that pigs have a greater respiratory response than cats or rabbits. A stepwise decrease in blood pressure through haemorrhage under iso‐PCO2 and iso‐PO2 conditions was found to affect the matching of the expiratory to the inspiratory time without affecting the activation threshold of the inspiratory cut‐off mechanism.
EFFECT OF SECRETIN ON INTESTINAL LYMPH FLOW AND COMPOSITION IN THE RAT
Authors: Lawrence J.-A. , Bryant D. , Roberts K. B. , Barrowman J. A.
Published: December 2014

The effects of natural porcine and synthetic secretin, given by intravenous bolus or infusion, on intestinal lymph flow and protein composition in unanaesthetized rats were studied. Both forms of secretin increased lymph flow and protein output from the lymph fistula; dose‐response relationships were determined. No change was observed in protein concentration in lymph or in the relative concentrations of large and small protein molecules during secretin‐induced enhanced lymph flow, compared with the basal state. These results are in keeping with an increase in the functional exchange vessel area of the small intestine produced by secretin. It is possible that secretin may play a part in the hyperaemia and augmented intestinal lymph flow which occurs in the post‐prandial period.
DIURESIS FROM STIMULATION OF LEFT ATRIAL RECEPTORS: ADH AND THE MALPIGHIAN TUBULES OF RHODNIUS PROLIXUS
Authors: Knapp Meryl F. , Linden R. J. , Pearson M. Joan
Published: December 2014

Stimulation of left atrial receptors causes a diuresis partly through a blood borne agent. Malpighian tubules of Rhodnius prolixus can detect a blood borne agent during the diuresis. It has been suggested that the agent is ADH but this is in dispute. In the present investigation, vasopressin (1–300 µ i.u. cm‐3) was found to have no effect on Malpighian tubule secretion when added to plasma, Rhodnius Ringer and Rhodnius Ringer +5‐HT. In addition, it was shown that incubation with sodium thioglycollate of plasma samples obtained from anaesthetized dogs, before and during stimulation of atrial receptors by distension of a balloon in the lumen of the left atrium, did not abolish the differences between test and control plasma samples detected by the Malpighian tubules. It is concluded that differences in plasma detected by the Malpighian tubules and related to the diuresis which results from left atrial stimulation are not attributable to changes in concentration of ADH.
BILIARY SECRETION IN CONSCIOUS RABBITS: ROLE OF THE ENTEROHEPATIC CIRCULATION OF BILE SALTS AND OF THE GALL BLADDER
Authors: Esteller A. , Jiminez R. , Lopez M. A.
Published: December 2014

The role of enterohepatic circulation of bile salts in biliary secretion in conscious rabbits has been investigated before and after cholecystectomy. Bile flow was higher and bile salt concentration lower in cholecystectomized than in intact rabbits: this could have been caused by a negative feed‐back effect on bile salt synthesis as the circulating bile salt pool increased. The effects of cholecystectomy on flow and bile salt concentration balanced each other. Bile flow and bile salt concentration declined after interruption of the enterohepatic circulation in both cholecystectomized and intact rabbits. Furthermore, the percentage of the flow of bile independent of bile salt secretion increased, while that independent of total analysed solutes decreased after the enterohepatic circulation was broken. These results confirm that the decrease in bile flow after interruption of the enterohepatic circulation is due to loss of bile salts and not of electrolytes.
QUANTITATIVE ASPECTS OF PREOPTIC THERMOSENSITIVITY IN THE CONSCIOUS OX
Authors: Calvert D. T. , Findlay J. D. , McLean J. A.
Published: December 2014

An attempt has been made to study the quantitative relationship between the temperature of the anterior hypothalamic/preoptic (AH/PO) region and heat balance in the conscious ox (Bos taurus) at a thermoneutral air temperature of 20 °C. Heat balance was measured by combined gradient‐layer and open‐circuit calorimetry and AH/PO temperature was controlled using a water‐perfused thermode.

Continuous warming or cooling of the AH/PO region caused a transient heat imbalance which shifted core temperature to a new stable level dependent upon the level of stimulation. The heat balance responses to continuous AH/PO warming included peripheral vasodilation and increased respiratory and cutaneous evaporative heat loss; those to AH/PO cooling consisted mainly of decreased heat loss. Heat production was largely unaffected by both AH/PO warming and cooling. The heat balance responses developed only slowly, reaching a peak up to 50 min after the start of stimulation and taking several hours to complete.

The change to stability in core temperature during continuous AH/PO stimulation and the additional heat loss prior to that stability were the most sensitive indicators of response of all the variables measured. A significant response was observed in these parameters even at the smallest stimulus level (less than 0·33 °C) and correlation of response with stimulus level was precise with a zero threshold for response. This suggests a continuity of operation of the AH/PO mechanism about zero.

Several responses showed a curved relationship between slope of response and stimulus level, such that the increment in response per unit increase in stimulus level became greater as stimulus level increased. The results suggest a two‐tier form of thermoregulation in the ox with AH/PO sensitivity to warming greater than its sensitivity to cooling. It appears also that AH/PO temperature is at least as dominant in the thermoregulatory mechanisms in the ox as it is in smaller animals.
HUMORAL NATURE OF THE URINE RESPONSE TO STIMULATION OF ATRIAL RECEPTORS
Authors: Linden R. J. , Sreeharan N.
Published: December 2014

The diuretic response to stimulation of left atrial receptors by distending small balloons located at the pulmonary vein‐left atrial junctions and in the left atrial appendage was studied in anaesthetized dogs in which bretylium tosylate, atenolol and atropine had been administered to effect blockade of renal nerves and to prevent increases in heart rate resulting from stimulation of atrial receptors. In these dogs, distension of the balloons was not associated with significant changes in heart rate, left atrial pressure or arterial blood pressure, and resulted in increases in urine flow, decreases in urinary sodium concentration and no significant changes in urinary sodium excretion. It is concluded that the humoral mechanism is responsible for the diuresis in response to stimulation of atrial receptors and has no significant effect on the response of natriuresis known to involve a decrease in the activity in the renal nerves and haemodynamic changes associated with stimulation of atrial receptors.
DIURESIS FROM STIMULATION OF LEFT ATRIAL RECEPTORS: INITIAL PURIFICATION STEPS FROM PLASMA OF THE CAUSATIVE AGENT
Authors: Knapp Meryl F. , Linden R. J. , Pearson M. Joan , Pither J. M. , Whitaker Elaine M.
Published: December 2014

This paper reports the initial purification steps of a humoral agent which may mediate the diuresis resulting from stimulation of left atrial receptors in anaesthetized dogs. The agent was shown to be stabilized in plasma by acidification to pH 3·2. Acid acetone precipitation was found to be a convenient method as a first stage in the purification of the humoral agent in plasma. Heat stability studies showed that the agent was stable in acidified plasma for up to 20 min of heating in a boiling water bath. Precipitation of plasma proteins under these conditions made this another possible first stage in the purification of the agent in plasma. Some general conclusions about the possible nature of the humoral agent are discussed.
PROLONGED PARALYSIS, CAUSED BY THE LOCAL INJECTION OF BOTULINUM TOXIN, FAILS TO CAUSE MOTOR NERVE TERMINAL SPROUTING IN SKELETAL MUSCLE OF THE FROG
Authors: Antony Marie T. , Sayers Helen , Stolkin C. , Tonge D. A.
Published: December 2014

Injection of a sublethal dose of botulinum toxin (type D) into the cutaneus pectoris muscle of the frog caused paralysis for about three months, but in contrast to previous studies in the mammal, did not appear to cause axonal sprouting from motor nerve terminals. In frogs in which the cutaneus pectoris had been denervated by crushing its nerve, reinnervation occurred within 2–3 weeks and axonal sprouts beyond the original end‐plates were often observed. When the hypoglossal nerve was implanted into the cutaneus pectoris, crushing the original nerve caused profuse axonal growth from the implanted nerve towards the denervated end‐plates within one week, whereas injection of botulinum toxin had little effect. Stimulation of the implanted nerve caused contraction of those cutaneus pectoris muscles whose original nerves had been crushed, but no response to stimulation of the implanted nerve was seen in those muscles in which botulinum toxin had been injected. The failure of botulinum toxin to induce nerve sprouting and acceptance of foreign innervation in the frog may be due to the fact that activity may play a less important role in the neural control of the physiological properties of muscle in this species than in the mammal.
MAMMARY CELL PROLIFERATION IN MICE DURING PREGNANCY AND LACTATION IN RELATION TO MILK YIELD
Authors: Knight C. H. , Peaker M.
Published: December 2014

Measurements have been made of body weight, mammary weight and total mammary DNA content (DNAt) during the second half of gestation and throughout lactation in mice. When corrected for conceptus weight and mammary weight, body weight was not significantly changed with advancing gestation but did increase during lactation. Mammary weight increased progressively until day 10 of lactation, then decreased until the end of lactation. On day 4 of involution mammary weight was not significantly different from that on day 12 of gestation. Mammary DNAt increased exponentially from day 12 of gestation to day 5 of lactation, with a mean doubling time of 6 d. No further increase was apparent at day 10, thereafter it fell in a similar manner to mammary weight. The incorporation of [3H]thymidine into mammary tissue was studied in vitro. [3H]Thymidine incorporation per unit weight of tissue was highest at mid‐gestation, fell during late gestation and then rose to a peak value 48 h post partum. For the remainder of lactation incorporation was very low. Incorporation calculated relative to DNAt showed similar, although less marked, changes. Milk yield of lactating mice has been estimated by daily weighing of the litter. Three phases were apparent: (i) a period from parturition to day 6 when milk yield was rising; (ii) a peak plateau from day 6 to day 10; (iii) a lower plateau from day 11 to day 15. Total daily litter weight gain was not significantly different between litters of nine and eighteen pups from day 7 to day 13 of lactation. Virgin and lactating mice were treated daily for seven days with 0·6 mg progesterone plus 0·2 µg oestradiol benzoate. This treatment significantly stimulated [3H]thymidine incorporation in the mammary glands of virgin mice and of mice in late lactation (days 9–15) but not in those of mice in early lactation (days 2–8). Milk yield was significantly reduced in the early‐lactation group, but not in the late‐lactation group.
COMPUTER ANALYSIS OF MECHANICAL ACTIVITY OF GASTRODUODENAL JUNCTION IN UNANAESTHETIZED DOGS
Authors: Ehrlein H. J. , Hiesinger E.
Published: December 2014

In four conscious dogs mechanical activity of the gastroduodenal junction was recorded with chronically implanted strain gauge transducers and induction coils. The data were evaluated by a computer. Analog circuits were used in order to reduce the data which were transferred to the computer. In the digestive state the contractions of the pyloric sphincter and duodenal bulb were correlated in such a way that the contractions of the duodenal bulb were inhibited when the gastric waves travelled across the antrum and that the bulb contracted once or twice when the peristaltic waves arrived at the gastroduodenal junction. However, the timing between pyloric and duodenal contractions was imperfect. Contraction maxima of the duodenal bulb often occurred before the pylorus was closed. This was due to the different inherent frequencies of the pyloric and duodenal contractions. In the interdigestive state the timing between the pyloric and duodenal contractions was as imperfect as during the digestive state. In phase III of the interdigestive activity, however, the strong antral contractions were regularly associated with inhibition of the duodenal bulb. This phenomenon can be interpreted as co‐ordination between gastric and duodenal activity.
INHIBITION OF MONOAMINE OXIDASE IN CHICKENS AND DUCKLINGS BY A MICROBIAL METABOLITE OF FURAZOLIDONE
Authors: Ali B. H. , Bartlet A. L.
Published: December 2014

In the chicken, monoamine oxidase (MAO) activity in the brain, heart and alimentary tract was inhibited when furazolidone was given at the therapeutic dose (0·04%, w/w, in the feed for 10 days). The inhibition of MAO activity was most marked in the rectal caeca and least in the liver, where no inhibition was found. Furazolidone treatment, probably in consequence of MAO inhibition, increased the amount of 5‐hydroxytryptamine (5‐HT) in the brain and potentiated the vasopressor action of tyramine. The amounts of adrenaline and noradrenaline in the brain were unaffected by the treatment, as was the vasopressor action of noradrenaline. Furazolidone (0·04%, w/w, in the feed, 10 days) inhibited MAO activity in the liver of ducklings but not chickens, indicating that hepatic clearance of the inhibitor was less efficient in the former species than in the latter. In other organs from the treated birds no species difference was apparent in the degree of MAO inhibition, and the effect of the treatment on the amounts of 5‐HT, adrenaline and noradrenaline in the brain was similar in chickens and ducklings. Neomycin antagonized the furazolidone acting as a MAO inhibitor in chickens and ducklings, following administration of the drugs by crop tube. This observation suggests that in these birds the alimentary microflora transformed furazolidone to an active metabolite which subsequently inhibited MAO activity in other organs. Although furazolidone is considered highly toxic in the duck, in the present experiments ducklings survived when it was given in the feed at a concentration of 0·04% (w/w) for 10 days or by crop tube at a dose of 200 mg/kg. It is suggested that the husbandry of the duck affects its susceptibility to furazolidone.
REGULATION OF URINE OSMOLALITY IN FETAL SHEEP
Authors: Wintour E. M. , Hennessy D. P. , Congiu M. , Hardy K. J.
Published: December 2014

Urine osmolality was measured daily from day of cannulation (80‐110 d) until term in six chronically cannulated ovine fetuses. Fetal urine was hypertonic to plasma following surgery, and 24‐36 h before parturition. On fifty‐five occasions plasma antidiuretic hormone (ADH) concentration was measured concurrently with urine osmolality. When fetal urine osmolality was 154 ± 45 mosmol/kg water, plasma ADH was 5·6 ± 2·1 pg/ml (mean ± S.D.; n = 33) in fetuses less than 120 d gestation. In ten samples from fetuses from 121 d to term urine osmolality was 118 ± 35 mosmol/kg water when the concurrent plasma ADH concentration was 5·5 ± 2·1 pg/ml. Urine osmolality 〉 300 mosmol/kg water was associated with endogenous plasma ADH concentrations of 6·2‐9·2 pg/ml in fetuses 86 d until term. However, when exogenous synthetic arginine vasopressin (AVP) was infused into non‐stressed fetuses with initial urine osmolalities 〈 200 mosmol/kg water, the minimum plasma ADH concentration that had to be established in order to induce the production of a hypertonic urine was 22·1 pg/ml at gestational ages 95‐105 d, 11·1 pg/ml at 110‐120 d and 7 pg/ml at 121‐130 d. The fetal kidney thus becomes more responsive to infused AVP over the last half of gestation. Under conditions of in utero stress, however, hypertonic urine can be produced at lower endogenous plasma ADH concentrations than required to be established by infusion in non‐stressed fetuses, suggesting that urinary concentrating mechanisms independent of ADH are established in these fetuses.
THE UTILIZATION OF LACTIC ACID BY SHEEP IN LATE PREGNANCY
Authors: Faichney G. J. , Barker P. J. , Setchell B. P. , Lindsay D. B.
Published: December 2014

Quarterly Journal of Experimental Physiology 66 (1981).

Page 195, Summary line 6, should read: About 22% of the glucose …
USE OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY TO STUDY ABSORPTION AND METABOLISM OF PURINES BY RAT JEJUNUM IN VITRO
Authors: Parsons D. S. , Shaw M. I.
Published: December 2014

A simple and specific analytical method incorporating high performance (anion‐exchange) liquid chromatography has been used to study the absorption and metabolism of some purine derivatives in an in vitro preparation of adult rat jejunum. When present in the lumen the purine bases guanine (4 x 10−5 M), hypoxanthine or xanthine (10−4−3 x 10−4 M) do not appear in the serosal secretions but the uric acid (UA) content of these secretions is increased. With UA in the intestinal lumen (10−4−3 x 10−4 M) the serosal UA is increased, in some cases to a higher concentration than that in the lumen. With adenine in the lumen (10−4−10−3 M) there is an increased appearance of UA and adenine also appears in the serosal secretions, but the concentration of adenine never exceeds that in the lumen.

It is concluded that purines absorbed from the lumen are significantly metabolized to UA during translocation across rat jejunum. Negligible amounts of metabolites are found in the luminal solutions except for guanine which appears to be degraded in the lumen.
SIMULTANEOUS PANCREATIC, GASTRIC AND HORMONAL RESPONSES TO 2‐DEOXYGLUCOSE IN THE CONSCIOUS PIG
Authors: Merritt A. M. , Kolts B. E.
Published: December 2014

The effect of vagal stimulation induced by 2‐deoxy‐D‐glucose (2DG) on gastric acid and pancreatic bicarbonate output, and portal gastrin and secretin concentrations, was assessed in conscious miniature pigs. Electrical vagal stimulation has previously been shown to induce profuse pancreatic water and bicarbonate secretion in anaesthetized pigs. Pigs in this study were surgically prepared with gastric and pancreatic fistulas and indwelling jugular and portal catheters. An intravenous bolus of 2DG (100 mg/kg body weight) caused a significant increase in both gastric acid and pancreatic bicarbonate output although the latter was about 50% of the reported response to electrical vagal stimulation. Portal gastrin concentration rose significantly after 2DG, but the portal secretin concentration did not change. The presence of secretin in the small intestine was confirmed by intrajejunal HCl infusion. Failure of portal secretin concentration to rise after 2DG infusion rules against a role for this hormone in the pancreatic response.
RENAL HAEMODYNAMICS IN CONSCIOUS EXPERIMENTALLY HYPERTENSIVE RATS
Authors: Charocopos Fotis
Published: December 2014

The integrity of renal haemodynamics is essential for the maintenance of normal renal function in the normotensive and hypertensive state. Systemic and renal haemodynamics have been determined by the radioactively labelled microspheres technique in normotensive, Goldblatt I, Goldblatt II and deoxycorticosterone (DOC)‐saline‐treated hypertensive rats. Cardiac output was similar between normotensive and hypertensive rats, while total peripheral resistance was similarly higher in all hypertensive animals when compared to normotensive animals. Renal blood flow per weight unit was similarly decreased in all hypertensive animals (3·77 ml/min.g (S.D. 0·85, n = 11); the unclipped kidneys of Goldblatt II rats, 3·76 ml/min.g (S.D. 0·89, n = 11); the clipped kidneys of Goldblatt II rats, 3·62 ml/min.g (S.D. 0·78, n = 9); the kidneys of Goldblatt I rats and 2·95 ml/min.g (S.D. 0·83, n = 10) the kidneys of DOC‐saline rats). It is concluded that kidneys from experimentally hypertensive rats fail to preserve normal renal blood flow, even at elevated arterial blood pressures, regardless of the pathophysiology of hypertension.
THE EFFECTS OF SAR1ALA8‐ANGIOTENSIN II IN VASOPRESSIN‐TREATED DEHYDRATED SHEEP
Authors: Kelly Catherine , Wholohan Therese , Yesberg Nancy E.
Published: December 2014

Mildly dehydrated conscious Merino ewes were infused with vasopressin (AVP) at 5 mu.min−1 alone and simultaneously with the angiotensin II receptor blocker sar1ala8‐angiotensin II (saralasin) at 15 µg.min−1. AVP was slightly pressor and produced an increase in the calculated total peripheral resistance, and an increase in glomerular filtration rate, urine flow and electrolyte excretion, without a change in total renal plasma flow. These results indicate renal efferent arteriolar vasoconstriction as well as other non‐renal vasoconstriction. Saralasin infusion checked the rise in total peripheral resistance (which continued to increase after saralasin withdrawal), but caused a marked increase in renal vascular resistance resulting in a decrease in renal plasma flow and to a lesser extent in glomerular filtration rate. These results suggest that saralasin was acting as an angiotensin II agonist in the kidney, but as an antagonist elsewhere. Deductions from previous experiments in the literature of the renal function of angiotensin II, based on its supposed inhibition by saralasin, may not be justified.
THE FATE OF ADENINE NUCLEOTIDES IN THE PULMONARY CIRCULATION OF ISOLATED LUNG
Authors: Chelliah R. , Bakhle Y. S.
Published: December 2014

The hydrolysis of ATP, ADP and AMP was studied in perfused isolated lungs from rats, hamsters, guinea‐pigs and humaps. In rats, ATP and ADP at concentrations up to 1 mM were extensively broken down to AMP and AMP itself was more resistant to further hydrolysis. This pattern of metabolites was maintained in rat lung perfused with Krebs solution containing albumin. The effects of endogenous sex hormones on ADP metbolism were studied in lungs from female rats at different stages of the oestrous cycle. There were no cycle‐related changes observed and in a comparison between sexes, only a small difference between males and females was apparent. Lung effluent from rat lungs exhibited a low level of ADPase activity. Although hamster lungs metabolized ADP to AMP as did rat lungs, lungs from guinea‐pigs and humans metabolized ADP and AMP extensively to adenosine. This difference means that although all species exhibit the ability to inactivate pro‐aggregatory ADP, the ability to form the anti‐aggregatory adenosine from ADP in the pulmonary vasculature varies markedly between species.
EFFECT OF DECREASED FEED INTAKE ON THE RESPONSE OF MILK SECRETION TO FREQUENT MILKING IN GOATS
Authors: Blatchford D. R. , Peaker M.
Published: December 2014

During declining lactation in goats, dietary intake was decreased and the animals switched from positive to negative energy balance. Milk yield and empty udder volume decreased. Goats on the reduced diet were milked hourly with the aid of oxytocin for 8 h. No stimulatory effect of hourly milking was observed. The results are discussed in relation to the factors which limit the rate of milk secretion in the declining phase of lactation.
EFFECT OF UNILATERAL HIND LIMB VIBRATION ON BLOOD RHEOLOGY IN RABBITS
Authors: Piggott Marisa , Ramcharan J. E. , Taylor D. E. M.
Published: December 2014

The right hind limb of twelve rabbits was vibrated for 15 min. Blood samples were taken before vibration from the right hind limb and after vibration from both the vibrated and the non‐vibrated hind limbs. A control series was also run. Estimations were made of: haematocrit, whole‐blood viscosity, erythrocyte ξ potential and plasma fibrinogen concentration. There was no significant change in whole‐blood viscosity in either limb after vibration. Erythrocyte ξ potential was significantly increased (in both limbs) after vibration. Fibrinogen concentration did not change (in either limb) after vibration. Yield stress was significantly reduced (in both limbs) after vibration. High Shear Casson Law slope decreased in the vibrated limb after vibration.
EFFECTS OF MODERATE INCREASES IN VITAMIN INTAKE BY RATS DURING PREGNANCY AND LACTATION
Authors: Shirley Barbara
Published: December 2014

Rats were given a multivitamin diet supplement during pregnancy and lactation that moderately exceeded recommended dietary allowances of the vitamins. The vitamin regimen had no significant effect on length of the gestation period, number of pups found alive on the day of their birth, weights of pups at birth or weaning (21 d), or survival of pups to weaning.
THE HYPOTHALAMIC SLICE APPROACH TO NEUROENDOCRINOLOGY
Authors: Hatton Glenn I.
Published: December 2014

The magnocellular peptidergic cells of the supraoptic and paraventricular nuclei comprise much of what is known as the hypothalamo‐neurohypophysial system and is involved in several functions, including body fluid balance, parturition and location. While we have learned much from experiments in vivo, they have not produced a clear understanding of some of the crucial features associated with the functioning of this system. In particular, questions relating to the osmosensitivity of magnocellular neurones and the mechanism(s) by which their characteristic firing patterns are generated have not been answered using the older approaches. Electrophysiological studies with brain slices present direct evidence for osmosensitivity, and perhaps even osmoreceptivity, of magnocellular neurones. Other evidence indicates that the phasic bursting patterns of activity associated with vasopressin‐releasing neurones (a) occur in the absence of patterned chemical synaptic input, (b) may be modulated by electrotonic conduction across gap junctions connecting magnocellular neurones and (c) are likely to be generated by endogenous membrane currents. These results make untenable the formerly held idea that phasic bursting activity is dependent upon recurrent synaptic inhibition.
INTERCOMMUNICATION IN THE RAT SUPRAOPTIC NUCLEUS
Authors: Leng G. , Dyball R. E. J.
Published: December 2014

The vasopressin and oxytocin cells of the rat supraoptic nucleus fire in characteristic discharge patterns during hormone release. The present paper discusses the possible role of intercommunication between supraoptic neurones in determining these patterns. In contrast to earlier reports, recent electrophysiological and anatomical evidence suggests that strong coupling is not widespread within the nucleus. However, it remains possible that local release of a neuromodulator, perhaps vasopressin itself, may modify the phasic discharge patterns of the vasopressin cells. The neurosecretory cells project to areas outside the nucleus, and also to a few interneurones within the nucleus, which may mediate indirect communication between the supraoptic neurones.
AN ESTIMATE OF CAPILLARY ANISOTROPY AND DETERMINATION OF SURFACE AND VOLUME DENSITIES OF CAPILLARIES IN SKELETAL MUSCLES OF THE CONGER EEL (CONGER CONGER L.)
Authors: Egginton S. , Johnston I. A.
Published: December 2014

Fast and slow muscle fibres were isolated from the axial muscles of conger eel (Conger conger L.) and examined by electron microscopy. Volume densities of mitochondria, Vv (mit, f); intracellular lipid stores, Vv (lip, f); and myofibrils, Vv (mf, f) were respectively 0·23, 0·18, 0·47 for slow and 0·03, 0·002, 0·79 for fast fibres. Factors affecting the representative sampling of capillary supply were investigated using semi‐thin (0·5 µm) sections. An estimate of the degree of capillary anisotropy was made using the assumption of a Fisher axial distribution (Mathieu, Cruz‐Orive, Hoppeler & Weibel, 1983). The capillary bed is highly anisotropic. Mean capillary cross‐sectional area, determined from electron micrographs, was 25·7 and 30·5, µm2 for slow and fast muscle, respectively. The number of capillaries per unit cross‐sectional fibre area, NA (c,f); volume Vv(c,f); and surface density, Sv(c,f) of capillaries was 615 mm−1 0·016, 135 cm−1 for slow and 21·3 mm−1 0·0007, 4·7 cm−1 for fast muscle, respectively. The relationship between the extent of the capillary bed and mitochondrial volume density is discussed in relation to the function of different muscle types.
EFFECT OF OLEIC ACID ON CANINE GASTRODUODENAL MOTILITY, PYLORIC DIAMETER AND GASTRIC EMPTYING
Authors: Keinke Oliver , Ehrlein Hans‐Jörg
Published: December 2014

The motility of the antrum, duodenum and pylorus was recorded with strain gauge transducers and induction coils in conscious beagle dogs. The effect of oleic acid on gastroduodenal motility and on the pyloric diameter was studied in the interdigestive state and during emptying of a mashed potato meal. The flow of digesta was observed fluoroscopically. Gastric emptying was measured by planimetry of the radiopaque gastric silhouette. The intraduodenal injection of oleic acid reduced the diameter of the pylorus in the empty stomach. In the digestive state oleic acid diminished gastric emptying of the potato meal. The antral motility was significantly diminished (amplitudes from 100 ± 39·2 to 93 ± 41·2 mV, contractile frequency from 4·3 ± 0·6 to 3·8 ± 1·5 min−1, motility index from 435 ± 197 to 345 ± 213 V, n = 3400‐4700 contractions), whereas the duodenal motility was enhanced (amplitudes from 100 ± 49·6 to 106 ± 58·6 mV, motility index from 548 ± 296 to 567 ± 377 V, n = 5800–6400 contractions). The diameter of the pyloric opening during the phase of relaxation was about 25% less in comparison to the control meal. The weaker antral contractions and the less opening of the pylorus diminished gastric evacuation and enhanced retropulsion of the gastric chyme. A higher incidence of segmental duodenal contractions produced a slower transfer of digesta. Results demonstrated that gastric emptying was regulated by several co‐operating factors. The pylorus was involved by producing different resistances to flow during its phase of relaxation.
EFFECTS OF FREQUENT MILKING ON MILK SECRETION AND MAMMARY BLOOD FLOW IN THE GOAT
Authors: Maltz E. , Blatchford D. R. , Peaker M.
Published: December 2014

When goats were milked every hour for 8 h without the use of exogenous oxytocin, milk ejection each hour appeared to be more complete than had previously been reported. Moreover, the rate of milk secretion increased by 15% over the period of hourly milking. There were no major changes in the composition of the aqueous phase of milk. Mammary blood flow was not apparently changed when goats were milked hourly: there was no significant effect of time of day (between 09.00 and 17.00 h) on blood flow. These results are discussed in relation to the mechanism by which frequent milking increases the rate of milk secretion.
CONVERTING‐ENZYME INHIBITION AND 1‐SARCOSINE‐8‐ISOLEUCINE‐ANGIOTENSIN II: EFFECTS ON RENAL FUNCTION IN THE DEHYDRATED SHEEP
Authors: Yesberg Nancy E. , Henderson Myrna , Dallemagne Catherine , Law Sandra , Hamilton D. , Cross R. B.
Published: December 2014

The effect of a converting‐enzyme inhibitor (captopril) was studied in nine conscious dehydrated Merino ewes. Captopril (4 mg I.V. over 40 min) caused significant decreases in mean arterial blood pressure (M.A.B.P.), renal vascular resistance (R.V.R.) and filtration fraction, and increases in urine flow (V), sodium excretion, glomerular filtration rate (G.F.R.), renal plasma flow, solute clearance (Cosm), solute‐free water reabsorption (TC,H2O) and plasma renin activity (P.R.A.). None of these effects was observed when captopril was similarly administered to sheep pretreated with angiotensin II (AII) receptor blocker, l‐sarcosine‐8‐isoleucine‐AII (sarileucin). It is concluded that the effects of captopril were probably not due to bradykinin potentiation but rather to decreased levels of circulating AII. The effect of sarileucin itself was complex. It effectively blocked the pressor response to administered AII, but it also had an AII‐like effect indicated by a rise in R.V.R., and decreases in V, G.F.R., Cosm and TC,H2O. This apparent mixture of All agonist and antagonist properties probably accounts for the absence of any change in M.A.B.P. or P.R.A. during sarileucin administration.