bluuebunny/crossref_metadata_2025 huggingface dataset:
DAILY RHYTHMS OF RENAL EXCRETION IN ARCTIC‐DWELLING INDIANS AND ESKIMOS
Authors: Lobban Mary C.
Published: December 2014

The daily rhythms of renal excretion of indigenous arctic subjects were recorded under natural conditions during the continuous midsummer daylight (Indians and Eskimos) and in the continuous darkness of midwinter (Indians only). The excretory patterns for water, potassium, sodium and chloride have been compared with those of a group of British control subjects, recorded when they were newly introduced into a summer arctic environment in adult life. In general, the excretory patterns of the arctic subjects contain a high proportion of abnormalities, such that the averaged patterns for the indigenous groups are less well defined than are those for the control group of subjects from a temperate zone. The loss of definition of the rhythms is most marked in the Eskimo subjects, where differences between day and night excretory rates have virtually disappeared.

Mathematical analysis of the individual results shows that the relative amplitude of the rhythm of potassium excretion decreases from British controls → summer Indians → winter Indians → summer Eskimos. The differences between control subjects and all indigenous subjects and between Indians and Eskimos are significant, and cannot be accounted for by variations in age, activity pattern or diet.

It is suggested that the normal daily alternation of light and darkness in the environment is important not only for the day‐to‐day maintenance of renal diurnal rhythms but also for the initiation and full expression of these rhythms in the early life of the human subject.
MOTONEURONE ACTIVITY AS A CAUSE OF DEGENERATION IN THE SOLEUS MUSCLE OF THE RABBIT
Authors: McMinn R. M. H. , Vrbová G.
Published: December 2014

The tenotomized soleus muscle of a spinal rabbit does not degenerate unless it is stimulated electrically. If the muscle is stimulated at a frequency of 10 imp./sec., the histological changes occurring resemble those of tenotomized muscles in animals without spinal cord section.

No decrease of tension can be found if untenotomized muscles of spinal rabbits are stimulated, indicating that no degeneration is taking place.

It is concluded that isotonic contractions without a load are harmful to the structural integrity of the slow soleus muscle.
ALBUMIN, TRANSFERRIN AND GAMMA‐GLOBULIN METABOLISM DURING LACTATION IN THE RAT
Authors: Jordan Susan M. , Morgan E. H.
Published: December 2014

The turnover of rat serum albumin, transferrin and γ‐globulin and their transfer to the milk was studied following injection of radioiodine‐labelled purified proteins to rats on the 2nd, 9th and 17th days of lactation. The concentrations of the three proteins were also measured in maternal serum, milk whey and the serum of the suckling young.

The concentrations and relative and absolute rates of turnover of each protein in maternal serum changed very little with progression of lactation. The concentration of transferrin in whey increased greatly as lactation progressed, while the concentrations of the other two proteins remained constant. The ratio of whey protein‐bound radioactivity to maternal serum activity was constant for each protein at the three stages of lactation. The specific activity of whey albumin and γ‐globulin also remained constant at 100 and 85 per cent respectively of the maternal serum values, while the transferrin specific activity fell from 100 per cent the maternal serum value in early lactation to 25 per cent of this value late in lactation.

It is concluded that all of the albumin and most of the γ‐globulin of rat whey is derived from the blood plasma, while an increasing amount of transferrin up to 75 per cent in late lactation, and a little γ‐globulin is synthesized in the mammary gland.
OBSERVATIONS ON THE COURSE OF THE METABOLIC EVENTS ACCOMPANYING MILD EXERCISE
Authors: Harris P. , Bateman M. , Bayley T. J. , Donald K. W. , Gloster J. , Whitehead T.
Published: December 2014

The ventilation and the oxygen uptake rise during the first 5 min. of mild exercise, remain at a new high level until the end of exercise, and then fall again during the succeeding 5 min. The response of the ventilation and the oxygen uptake are, therefore, similar to the output of a simple damped system in the presence of a square‐waved input.

The metabolic response is considerably more complex than the respiratory. This is not only because of the divergent changes of many different substances, but also because these changes arise at specifically different times during the course of events.

There appear to be three major groups of disturbances of the composition of the blood accompanying exercise ‐ one group associated with beginning of exercise, one group which is maintained throughout exercise, and one group which is specifically associated with the period of recovery.

During the first 5–15 min. after the beginning of exercise there is an increase in the concentration of lactate and pyruvate, the latter reaching its maximum about 5 min. after the former. The increased concentration of lactate is associated with a fall in pH and standard bicarbonate. At the same time there is a transient fall in the free fatty acids in the plasma. All these phenomena also accompany exercise of shorter duration, in which case they continue to evolve after exercise has stopped and the concentration of lactate remains high long after the oxygen uptake has returned to its initial resting level.

More prolonged exercise reveals a number of disturbances which would seem to continue indefinitely during the period of exertion. These consist of a certain degree of elevation of the concentration of lactate and pyruvate, and of the serum potassium, sodium and inorganic phosphorus. The concentration of free fatty acids is maintained at a level at or a little above that which existed before exercise. The concentration of glucose is not greatly affected.

Immediately after the end of prolonged exercise, the concentration of lactate declines, although, in mild exercise, this usually appears to be a continuation of a process which had already started during exercise. By contrast, during the first few minutes of recovery, the concentration of pyruvate usually shows a transient increase which is followed by a more sustained fall. The concentrations of potassium, sodium and phosphorus fall again at this time, and there is evidence from the literature that a sustained and substantial fall in phosphorus may occur. Immediately after the end of excercise, there is an increase in the concentration of glucose and free fatty acids which may be of considerable magnitude and duration.
THE INTESTINAL AND HEPATIC CONTRIBUTIONS TO THE FLOW AND COMPOSITION OF THORACIC DUCT LYMPH IN YOUNG MILK‐FED CALVES
Authors: Shannon A. D. , Lascelles A. K.
Published: December 2014

The establishment of recirculating lymphatico‐venous shunts permitted the repeated collection of lymph from either the thoracic or intestinal duct in healthy calves. Hepatic lymph was also collected from calves with lymphatic fistulæ. The operations were carried out on calves in the first week of life.

The mean flow of thoracic duct lymph from four calves was 9·73 ml./kg./hr., of intestinal lymph from three calves 8·25 ml./kg./hr. and of hepatic lymph from two calves 0·64 ml./kg./hr. During the experiment the calves were fed 2·27 litres (0·5 gal.) of cow's milk twice daily. The mean protein concentration of lymph from the thoracic, intestinal and hepatic ducts was 56·5, 56·7 and 80·6 per cent, respectively, of the plasma levels. Thus the intestinal lymph contributed most of the volume of lymph and output of protein from the thoracic duct. It was estimated that 275 and 330 per cent of the volume and 155 and 190 per cent of the total protein of the blood plasma compartment passed through the intestinal and thoracic ducts, respectively, in a 24‐hr. period.

There was a rapid transfer of T‐1824‐labelled albumin from plasma into intestinal and hepatic lymph in the young calf. Equilibration of the specific activity curves for plasma and for intestinal and hepatic lymph occurred within 100 min. after the injection of the T‐1824.

The lipid composition of intestinal lymph was found to be very similar to that of thoracic duct lymph. The concentrations of triglyceride and free fatty acid in hepatic lymph were 350 and 170 per cent, respectively, of those in plasma. It is suggested that a triglyceride‐rich component and free fatty acid were released from the liver into the hepatic lymph.

The high flow and output of protein from the intestinal duct may be related to the absorption of large quantities of fat in young milk‐fed calves.
THE ANTAGONISM OF Ca2+ BY Na+ AND OTHER MONOVALENT IONS AT THE FROG NEUROMUSCULAR JUNCTION
Authors: Kelly J. S.
Published: December 2014

The quantal content of the e.p.p. and the frequency of the m.e.p.p.s in the presence of enhanced extracellular K+ have been investigated by intracellular recording from frog sartorius muscle fibres. In the presence of 0·23 mM Ca2+ (one eighth of the normal), the replacement of NaCl by sucrose or glycine led to a large increase in quantal content; the size of this increase appeared to be related to the amount of NaCl replaced. The quantal content in 0·9 mM Ca2+, however, was not appreciably altered by the replacement of NaCl by sucrose. When LiCl was used to replace NaCl, the immediate change in the quantal content was small. With methyl‐ and ethylammonium or tris chlorides as substitutes for NaCl, the immediate effect was a reduction in quantal content. A delayed effect of LiCl was a reduction, and that of methylammonium an increase, in quantal content. The replacement of NaCl by sucrose accelerated the m.e.p.p. frequency in the presence of enhanced K+ (12 mM); in contrast the replacement of NaCl by methylammonium chloride caused a reduction in frequency. With LiCl as a substitute the frequency of the m.e.p.p.s increased in the normal K+ concentration, the increase being slowly reversible in the normal Ringer solution.

It is suggested that antagonism of Ca2+ by Na+ is non‐specific and that other monovalent cations will also compete with Ca2+.
ABSORPTION OF VOLATILE FATTY ACIDS, TRITIATED WATER AND ANTIPYRINE FROM THE ABOMASUM OF GOATS
Authors: Engelhardt W. v. , Ehrlein H. ‐J. , Hörnicke H.
Published: December 2014

In conscious goats the abomasum was isolated temporarily from the rest of the gastro‐intestinal tract by means of balloons, or a double by‐pass or a snare around the pylorus. Abomasal contents, rumen fluid or a saline solution were given into the abomasum. Altogether forty experiments were done on four goats.

The absorption of acetic acid, propionic acid, butyric acid, tritiated water (HTO) and antipyrine (AP) from the abomasum was measured. For comparison of the absorption rates, the data were given as clearance of the abomasal fluid and as water diffusion.

At a mean abomasal fluid volume of 606 ± 201 ml., 513 ± 169 ml. water diffused out of the abomasum through the abomasal mucosa per hour. The antipyrine clearance was 214 ± 84 ml./hr. The volatile fatty acids (VFA) were absorbed considerably faster at acid than at neutral pH values; at pH 5·2 — 5·6 the VFA clearance was only 320 ml./hr.: at pH 3·5−4·0, however, it increased to 1130 ml./hr.

The olive oil: water partition coefficients for acetic, propionic and butyric acid were measured in the pH range of 3·5 −6·2. With decreasing pH values the degree of dissociation of the acids decreases and the lipid solubility increases considerably. The permeability of the abomasal and ruminal mucosa for VFA also increases at lower pH values, but not as much as the olive oil : water partition coefficients of the acids.

Absorption of VFA, HTO and AP from the abomasum is discussed in relation to the absorption of these substances from the rumen and the human stomach.
BLOOD FLOW AND OXYGEN CONSUMPTION OF THE UTERUS OF THE NON‐PREGNANT EWE
Authors: Huckabee William E. , Crenshaw Carlyle , Curet Luis B. , Barron Donald H.
Published: December 2014

Observations on the coefficient of oxygen utilization of the uterus have been made for periods of days and weeks in a series of ‘unstressed’ non‐pregnant ewes by means of indwelling catheters in an artery and the uterine vein. They indicate that the rate of oxygen transport to the uterus with respect to its oxygen consumption varies over a wide range. The two rates (ml./kg./min.) were estimated in twenty ‘unstressed’ ewes that had been divided into three groups on the basis of the appearance of the ovaries and uterus at laparotomy 2 or 3 days earlier. In ten ewes, at least one ovary contained a large protruding corpus luteum (Group I); in three, one ovary contained one or more large follicles (Group II) whereas in seven the ovaries lacked either of these distinguishing features (Group III). The average rates of uterine blood flow and oxygen consumption in these three groups were 119 and 5·26; 540·6 and 5·0 and 267·4 and 5·4 respectively.
THE EFFECT OF ENVIRONMENTAL TEMPERATURE ON HEALING OF BONE LESIONS IN THE RAT. II. THE EFFECT OF BONE INJURY ON MINERAL METABOLISM AT 20° C. AND 30° C
Authors: Cuthbertson D. P. , Tilstone W. J.
Published: December 2014

Fracture of a radius in rats living at 20° C. and 300° C. leads to a greater whole‐body retention by both groups of a tracer dose of 85Sr injected at the time of fracture, compared to the whole‐body retention found in isothermally housed uninjured controls. A simple small dental drill‐hole lesion of the tibia resulted in an enhanced whole‐body retention of tracer only in rats living at 300° C.

There is evidence of skeletal mobilization of calcium on fracture of a bone in rats at 20° C., but not in those at 30° C. However, there were no histologically observable differences in healing of bone lesions between the two groups of rats.
EFFECTS OF ADRENALIN AND ANAPHYLAXIS ON THE AGGREGATION OF THE CELLULAR CONSTITUENTS OF THE BLOOD IN VIVO
Authors: Stehbens W. E.
Published: December 2014

The effect of adrenalin and anaphylaxis on the behaviour of leucocytes, erythrocytes and platelets in the microcirculation was observed by means of transparent chambers inserted in rabbits' ears. Within one minute of the intravenous administration of adrenalin, blood flow became more brisk and within 2 to 5 minutes, extensive platelet aggregation and platelet leucocyte microthrombi were observed. After 6 to 7 minutes flow reverted to normal but microthrombi persisted for as long as 30 minutes. Anaphylaxis was induced by the administration of horse serum to sensitized rabbits, the first observable effect upon the injection of the shocking dose being platelet aggregation and the sticking of leucocytes to the vessel wall. Red cells adhered to leucocytes and to one another in aggregates, at times forming distinct sludge before the flow markedly diminished at about 4 minutes. These changes occurred invariably, quite irrespective of the death or survival of the rabbit. Sludging of erythrocytes was universal and so prominent that it appears to be a contributory factor in the production of anaphylactic shock. Adrenalin administration greatly improved the flow in anaphylaxis, but had no direct desludging effect on erythrocyte conglutination.
STUDIES ON THE FIBRINOLYTIC ACTIVITY OF AN EXTRACT FROM VASCULAR ENDOTHELIUM
Authors: Pugatch E. M. J. , Poole J. C. F.
Published: December 2014

A method is described for the preparation of an extract from normal vascular endothelium. Experimental study of this material indicates that it has the properties of a plasminogen activator.
THE PERMEABILITY TO 131I‐PVP OF THE NORMAL AND HYPERTROPHIED GASTRO‐INTESTINAL TRACT OF SHEEP
Authors: Fell B. F. , Regoeczi E. , Campbell Rosa M. , Mackie W. S.
Published: December 2014

The permeability to 131I‐PVP of the gastro‐intestinal tract was studied in non‐breeding ewes, in post‐parturient ewes with alimentary hypertrophy, and in post‐weaning ewes in which the enlarged intestines were undergoing involution. A method for measuring the clearance of 131I‐PVP from the plasma by the gastro‐intestinal tract is presented and is shown to be more sensitive than that of expressing faecal radioactivities as a fraction of the intravenous dose.

The clearance of 131I‐PVP by the gastro‐intestinal tract in non‐breeding ewes was 4·29 per cent of the total clearance from the blood; during the development of alimentary hypertrophy the clearance was 5·09 per cent, and in a group with maximum hypertrophy, 4·91 per cent. These increases were not statistically significant (P〉0·01, but 〈0·05), but the mean clearance value of 6·81 per cent during the atrophy of the intestinal mucosa was significantly higher than the corresponding value in any other group (P〈0·01).

The clearance of 131I‐PVP from the plasma via the bile and pancreatic secretions in two normal sheep was equal to about 2 per cent of the total plasma clearance of PVP.

It is concluded that the increase in permeability during the post‐weaning atrophic phase of the gut is probably insufficient to cause marked alterations in the catabolism of plasma proteins. The half‐life of serum albumin was measured in both lactating and non‐breeding ewes, and the conclusion that gastro‐intestinal hypertrophy in the lactating ewe is not accompanied by a significant increase in permeability to macromolecules is supported by the finding that the half‐life of serum albumin is not affected by lactation.
THE ROLE OF TRANSFERRIN IN PLACENTAL IRON TRANSFER IN THE RABBIT
Authors: Baker Erica , Morgan E. H.
Published: December 2014

The role of transferrin in the process of iron uptake by the fœtus has been investigated in the pregnant rabbit. The specific binding of transferrin to the fœtal part of the placenta has been demonstrated using radioiodine labelled transferrin. Radioiodine labelled albumin was administered simultaneously to estimate and correct for the tissue distribution of transferrin due to the plasma content of the placenta. The capacity of the fœtal part of the placenta to bind transferrin increased markedly from the 15th to the 28th day of gestation, paralleling the sharp increase in the rate of iron transfer through the fœtal part with advancing pregnancy. Iron‐saturated transferrin was bound three times as avidly as iron‐free transferrin. The transferrin binding capacity of the fœtal part of the placenta was greater than that of the bone marrow, and far greater still than that of the maternal liver and spleen. There was no evidence for a specific binding to the placenta of transferrin present in the fœtal circulation.
LIPID DIGESTION IN THE SHEEP: EFFECT OF BILE AND PANCREATIC JUICE ON THE LIPIDS OF INTESTINAL CONTENTS
Authors: Leat W. M. F. , Harrison F. A.
Published: December 2014

The effect of bile and pancreatic juice on the pattern of lipids in the intestinal digesta of the sheep has been examined using animals suitably prepared with chronic intestinal fistulæ. The major lipid of digesta collected anterior to the common bile duct was the free fatty acid fraction composed mainly of palmitic and stearic acids. Digesta collected immediately posterior to the common bile duct contained, in addition, polyunsaturated fatty acids and lecithin, indicating that these lipids originated in the mixed secretions of bile and pancreatic juice. In the mid jejunum the major phospholipid was lysolecithin derived from the hydrolysis of lecithin by pancreatic enzymes. In the duodenum and jejunum the free fatty acids were associated mainly with the particulate matter of digesta, but in the ileum the free fatty acids were more evenly distributed between the particulate and aqueous phases. Negligible amounts of monoglyceride were present in digesta of the small intestine. Diversion of bile and pancreatic juice from the intestine resulted in the disappearance of lysolecithin and a decrease in the content of unsaturated fatty acids in the digesta of the jejunum. The digestion of lipids in the sheep intestine is discussed in relation to the possible role of bile and pancreatic juice. It is suggested that a major function of pancreatic juice is to provide, by interaction with biliary lecithin, the lysolecithin required for optimum micelle formation and lipid absorption.
DIMETHYL SULFOXIDE: INFLUENCE UPON FROG TADPOLE METAMORPHOSIS
Authors: Hammerman David L. , Ritterman Diane Paula
Published: December 2014

In normally metamorphosing tadpoles, dimethyl sulfoxide (DMSO) 1 per cent (v/v) in the medium significantly increases the time required for the completion of metamorphosis. When larval involution is induced, exogenous thyroxin counteracts the inhibitory effect of DMSO. It is suggested that DMSO inhibits metamorphosis by preventing the formation of thyroid hormones, or by inactivating them when formed, or both.
ACTION OF OXYTHIAMINE AND PYRITHIAMINE ON THE ISOLATED RAT SUPERIOR CERVICAL GANGLION
Authors: Perri V. , Sacchi O. , Casella C.
Published: December 2014

Incubation of isolated preparations of the superior cervical ganglion of the rat in the presence of low concentrations of oxythiamine and pyrithiamine results in an early and pronounced decrease of the post‐ganglionic potential. This effect is particularly evident with regard to oxythiamine.

The depressant action of both antithiamines on ganglion transmission appears to be specifically due to their metabolic competition because it can be completely prevented by the presence of equimolecular amounts of thiamine in the incubating medium.
THE RAT HEPATOCYTE AFTER EXPOSURE TO HIGH ALTITUDE: STRUCTURAL AND CHEMICAL CHANGES
Authors: Burgos M. H. , Zangheri E. O. , Parisii I. M.
Published: December 2014

One‐day‐old rats were exposed for 2 weeks in a low pressure chamber at a simulated altitude of 4,700 m. Then total esterified fatty acids, phospholipids and glycogen were determined in their livers, and electron microscopy of the liver cells was carried out. Normal rats of the same age were examined as controls. In the rats exposed to simulated high altitude, total esterified fatty acids were more than thrice the control value, phospholipid the same as the control value, and glycogen less than the control value. Their hepatocytes showed a marked increase in cytoplasmic lipid droplets, most pronounced near the central vein of the hepatic lobules; a marked diminution in rough endoplasmic reticulum; and generally absence of glycogen particles. Dense mitochondria of normal appearance were seen very closely apposed to the lipid droplets.

Altitude appears to interfere with the normal development of the hepatocyte, which remains in a rather enzymatically immature stage.
STRUCTURE AND FUNCTION OF LYMPHATIC VESSELS OF THE BAT'S WING
Authors: Cliff W. J. , Nicoll P. A.
Published: December 2014

The lymphatics of the bat's wing could be separated in vivo into two morphologically and functionally distinct types. Vessels selected for subsequent electron microscopy were labelled in vivo with Berlin blue which could be readily identified in the electron microscope. The terminal bulbs which are responsible for absorption of fluid and particles from the tissues have walls composed of a single layer of endothelium lined on its abluminal surface by a generally tenuous condensation of fibrillar material. Absorption is considered to occur through large gaps present in the endothelial lining. Although the endothelial junctions have no specialized attachment zones, no evidence was obtained for any flap‐valve action in these regions. No gaps were found in the endothelial layers of the collecting and transport channels. The transport channels which are contractile and are responsible for the propulsion of lymph in vivo contain smooth muscle cells in their walls. These cells are not innervated. The cusps of the lymphatic valves are simply two layers of endothelium separated by a narrow zone containing fine fibrillar material. The endothelial cells are phagocytic to the marker particles.
OBSERVATIONS ON THE ‘SURROUND’ PROPERTIES OF THE RECEPTIVE FIELDS OF FROG RETINAL GANGLION CELLS
Authors: Keating M. J. , Gaze R. M.
Published: December 2014

The activity of frog retinal ganglion cells has been studied, using metal filled micropipette electrodes and recording the activity in either the optic nerve or the superficial neuropil of the optic tectum. It is a feature common to all such cells that their activity can be modulated by retinal stimulation of an area surrounding the excitatory receptive field (ERF).

It has been demonstrated that the inhibitory ‘surround’ for sustained edge units (class 1 and 2) is considerably larger than previously realized, extending up to 45° from the edge of the ERF.

An inhibitory surround to the receptive fields of ‘on’ units has been demonstrated. In addition an unsuspected complexity of the surround organization of dimmer units (class 4) has been found.
EFFECT OF THE ENTEROHEPATIC CIRCULATION OF BILE SALTS ON THE FLOW OF BILE AND ITS CONTENT OF BILE SALTS AND LIPIDS IN SHEEP
Authors: Heath Trevor , Caple Ivan W. , Redding Paul M.
Published: December 2014

When bile was diverted from the intestine of four sheep for 12–48 hr, they secreted 0·31 ± 0·019 ml. bile/min. This contained 5·0 ± 0·55 µEq total fatty acids, principally in phosphatidylcholine (48 ± 1·9%) and lysophosphatidylcholine (31 ± 5·0%). The output of total fatty acids increased when taurocholate was infused into the portal vein or duodenum, and this was due to an increased secretion of phosphatidylcholine. Stimulation of total fatty acid secretion by bile salts was most marked at low rates of bile salt transfer, and reached a maximum when taurocholate was infused into the portal vein at 37 µM/min or more. The mean maximum output of total fatty acids in the bile of 12 sheep was 15·2 ± 1·41 µM/min. When 14C‐palmitic acid was infused into the portal vein with the taurocholate, it appeared in biliary phospholipids, and by the sixth hour of the infusion the level of radioactivity in bile was 8·3% of the rate of infusion. When taurocholate was infused into the portal vein at 45 µM/min or less it was transferred quantitatively into bile, but the efficiency of transfer decreased at higher infusion rates. Secretion of bile salts into bile was accompanied by increased secretion of water, but the volume of water accompanying each micromole of bile salt decreased with increases in the rate of secretion. The bile flow did not increase further when more than 127 µM/min taurocholate was infused into the portal vein, and in four sheep the maximum rate was 1·06 ± 0·052 ml./min. It is suggested that availability of bile salt may limit secretion of phospholipid into bile when the rate of secretion of bile salt is low, but that when large amounts of bile salt are secreted into bile some other factor, possibly the rate of phospholipid synthesis, limits the secretion of phospholipids into bile.
STATISTICAL ANALYSIS OF GRANULE SIZE IN THE GRANULAR CELLS OF THE MAGNUM OF THE HEN OVIDUCT
Authors: Covey‐Crump Peter A. K.
Published: December 2014

Statistical analysis of granule size in the granular cells of the fowl oviduct supports the hypothesis that these granules can be allotted to six different size groups.
EFFECTS OF ACETYLCHOLINE AND CARBACHOL ON THE BLOOD VESSELS OF THE FROG
Authors: Gambhir S. S. , Das P. K.
Published: December 2014

The effects of a few cholinergic agents, especially acetylcholine and carbachol, were studied on the perfused systemic blood vessels of the frog. Nicotine, adrenaline, isoprenaline, papaverine and barium chloride were used as controls. Acetylcholine (ACh) and carbachol (CCh) were found to be potent vasoconstrictors, confirming the report of Rahman [1963] with ACh. The vasoconstrictor action of choline and pilocarpine was much weaker. The ACh action was only partially inhibited by pentolinium, but the actions of ACh as well as CCh remained unaffected by tolazoline, gallamine and d‐tubocurarine. Atropine nearly completely blocked the vasoconstrictor responses of ACh and CCh though the skeletal muscle spasms caused by these choline esters remained unaffected. The results indicate that the nicotinic activity of ACh and CCh did not play any major role in the vasoconstrictor actions in frogs. Decrease in perfusion rate was also not due to spasms of skeletal or non‐vascular smooth muscle. It appeared that the action is chiefly mediated through atropine sensitive receptors.
ACTION POTENTIAL MODIFICATIONS IN RAT MYOCARDIAL CELLS DURING VITAMIN A DEFICIENCY
Authors: Rindi G. , Ventura U. , Ceriani T. , Zelaschi F.
Published: December 2014

Ventricular cell action potentials were measured in situ using intracellular microelectrodes in the hearts of vitamin A‐deficient rats, both at the spontaneous heart rate and at rates increased to various higher levels. The changes found indicate that a lack of vitamin A in the tissue may modify the ion permeability underlying cardiac electrogenesis, without affecting cardiac energetic metabolism. Results are discussed in the light of recent theories that vitamin A may stabilize the structure of cell membranes and control their permeability.
THE ISOLATED PERFUSED LIVER OF THE SHEEP: AN ASSESSMENT OF ITS METABOLIC, SYNTHETIC AND EXCRETORY FUNCTIONS
Authors: Linzell J. L. , Setchell B. P. , Lindsay D. B.
Published: December 2014

A technique is described for perfusing in isolation the livers of Soay sheep. Thirty‐two livers were perfused for 3–8·5 hr and their normality assessed by histology and by measuring blood and bile flow, Bromsulphthalein (B.S.P.) clearance, the uptake of O2 and infused NH3 and propionate, the production of CO2, urea and glucose and changes in tissue glycogen and weight. With portal pressure set below 10 mm Hg and arterial pressure set at l10 mm Hg, blood flow was 90–400 ml./100 g/min, 3–35 per cent of which came from the hepatic artery. Stimulation of nerves around the hepatic artery caused vasoconstriction in hepatic and portal vascular beds. Maximum bile flow during perfusion was similar to pre‐perfusion values, but generally declined to 20–75 per cent. The extraction of B.S.P. from the blood was inversely related to total blood flow, but directly to the hepatic artery flow. The percentage of injected B.S.P. appearing in the bile was related to bile flow. Perfused livers appeared normal histologically but small amounts of GOT (aspartate amino transferase) were released into the perfusate continually. O2 consumption averaged 1·8 ± 0·21 ml./min/100 g liver with no substrate added to the perfusate and 3·28 ± 0·28 when ammonium propionate was added. Liver glycogen generally (but not invariably), fell during perfusion. Glucose and urea outputs were greatly stimulated by the addition of ammonium propionate to the perfusate, and carbon from 14C propionate was transferred to glucose and CO2. The maximum rate of glucose production from propionate was comparable to that attained in the intact animal, but urea production from ammonia was less than values for the entry rate of urea into the circulation, from all sources, reported in the intact animal.

The sheep liver, even when taken from a shot animal, appears to perfuse as well as rat or dog liver, and should be a useful preparation for studying gluconeogenesis and liver function in ruminants.
CARDIOVASCULAR PARAMETERS IN SHORN SHEEP PRIOR TO AND DURING THEIR EXPOSURE TO A COLD, WET ENVIRONMENT
Authors: Panaretto B. A. , Vickery Marion R.
Published: December 2014

When shorn sheep were exposed to ambient temperatures of 3°C and the residual fleece was wetted, heart rate and cardiac output increased substantially above levels measured during a control period at 25°C. With continued cold exposure and wetting the sheep become hypothermic and heart rate and cardiac output decreased. In most sheep at rectal temperature 〈32°C cardiac output had fallen below control values while heart rate remained above control. In a minority of hypothermic sheep cardiac output remained above control rates.
THE EFFECT OF ANTIDIURETIC HORMONE ON THE PERMEABILITY OF THE VESSELS OF THE RENAL MEDULLA OF THE RAT DURING WATER DIURESIS
Authors: Williams Margaret M. M. , Moffat D. B. , Creasey Margaret
Published: December 2014

Diuresis was induced in 40 Wistar rats by the intraperitoneal injection of water. Of these animals, 20 were given, during the diuresis, a subcutaneous injection of 50 mU of Pitressin Tannate in oil. The extravascular protein in the renal medulla was estimated by injecting Evans Blue as a protein label, washing out the medullary vessels with saline and estimating the Evans Blue remaining in the tissues by a spectrophotometric method. It was found that after Evans Blue had been allowed to circulate for 2 min, almost twice as much extravascular dye was found in the diuretic rats as in those which had been treated with ADH. It is suggested that the extravascular protein hinders the removal of interstitial water by the vasa recta during diuresis, while during antidiuresis the oncotic pressure within the vessels causes removal of water from the medulla by means of the ascending vasa recta.
A NEW METHOD FOR ESTIMATING THE HEAT PRODUCTION OF ANIMALS
Authors: Blaxter K. L. , Brockway J. M. , Boyne A. W.
Published: December 2014

A new type of respiration chamber is described which avoids the need for absorption of carbon dioxide or for the measurement of large gas flow rates. The system is an extension of the ‘confinement’ principle for the measurement of respiratory gas exchange. The chambers are large enough to accommodate an adult cattle beast, but sufficiently flexible in operation to be used with individual sheep. Operation of the system is fully automatic, and information is recorded on the paper tape output from data logging equipment. The day‐to‐day variation in heat production by pairs of sheep kept in one chamber for periods of from 3 to 5 days was assessed; the coefficient of variation for heat production was 3 per cent.
WATER, SODIUM AND POTASSIUM MOVEMENTS ACROSS THE RUMEN WALL OF SHEEP
Authors: Warner A. C. I. , Stacy B. D.
Published: December 2014

Saliva was entirely diverted from the rumen of sheep via an oesophageal fistula and usually replaced by infusion of a synthetic saliva of known composition. Water movements in the rumen were measured by the use of soluble markers, and sodium and potassium movements were calculated. Water and various solutions were added to the rumen to vary its osmolality over the range 180–550 m‐osmole/kg.

When saliva was not replaced, recovery of the normal rumen osmolality following water loading was very slow indeed. When saliva was replaced by a synthetic solution the rate of water movement across the rumen wall (y, [l./hr]) was a linear function of the osmotic pressure (x, [m‐osmole/kg]), such that y = 0·404–0·001206x (r = ‐0·90). This suggests that the filtration permeability of the rumen wall was similar to that of frogskin or toad bladder.

Potassium absorption across the rumen wall was also slow but positively related to the potassium concentration. Sodium absorption appeared to depend on the potassium concentration and the osmotic pressure as well as on the sodium concentration. While moderate levels of potassium increased the rate of sodium absorption, grossly high levels, sufficient to produce a substantial entry of water across the rumen wall, decreased it, sometimes markedly. The rate of potasium and perhaps sodium absorption seemed to depend on the immediate state of nutrition of the animal.
QUANTUM CONTENT IN GUINEA‐PIG SERRATUS ANTERIOR
Authors: Reid John
Published: December 2014

Neuromuscular transmission has been studied in the serratus anterior muscle of the guinea‐pig. Series of evoked end‐plate potentials were recorded intracellularly in the presence of (+)‐tubocurarine chloride, and mean quantum content estimated from the mean and variance of their amplitudes. Mean ± standard error for these estimates was 156 ± 18. Using the present data, alternative methods for estimating mean quantum content have been compared and discussed, and a new formula has been shown for determining the standard error of individual mean quantum content estimates.
PERFUSION OF THE ISOLATED MAMMARY GLAND OF THE GOAT
Authors: Linzell J. L. , Fleet I. R. , Mepham T. B. , Peaker M.
Published: December 2014

Improvements to a previously reported technique for the perfusion of isolated goat mammary glands are described. Secretion of milk of relatively normal composition in vitro has been maintained at approximately 50% of the in vivo rate for about 12 hr. Factors found to be important for successful perfusion are a normal rate of mammary blood flow, the provision of adequate glucose, acetate and amino acids, and the inclusion in the circuit of an efficient oxygenator and dialyser.

Contrary to earlier results successful perfusions have been performed with glands from anaesthetized and from shot animals, although removal of glands from the tranquillized animal under spinal anaesthesia is still preferred. There was a marked dependence of milk secretion rate on the rate of blood flow below a critical value, but at supra‐normal flows there was no correlation between these variables. Evidence has been obtained suggesting that kinins or similar substances may be formed during perfusion.

The specific dependence of milk secretion on glucose is again stressed. Other carbohydrates sustained oxygen consumption similar to that shown with glucose, but by contrast did not support the secretion of water, a small amount of milk low in lactose but high in fat and protein being produced. Although milk fat secretion was dependent on the provision of acetate, the omission of β‐hydroxybutyrate, lactate and neutral fat (all shown to be absorbed by the gland in vivo) from the substrate mixture did not seriously impair milk fat secretion in vitro. Amino acids were shown to be necessary for normal rates of milk protein secretion, but the alteration of the substrate mixture to correspond to the amino acid absorption observed in vivo produced no significant change in milk secretion from that observed when amino acids were infused at rates corresponding to their occurrence in casein. The infusion of B vitamins and various hormones had no effect on milk secretion. Perfusions carried out with a conscious goat in circuit were no more successful than the completely in vitro system, but glands grafted onto recipient goats (even males) following complete removal from the donors produced substantially more milk than in vitro preparations.

In some experiments milk [Na] and [Cl] increased during perfusion while [K] and [lactose] decreased, these trends being apparent in milk secreted before perfusion was begun and being probably due to the oxytocin used to produce milk ejection. In other experiments milk [Na] and [Cl] showed little change but [K] and [lactose] tended to rise.

Possible factors limiting the performance of perfused organs are discussed.
THE MECHANISM OF THE PERMEATION OF CELLS BY NON‐ELECTROLYTES
Authors: Fisher R. B. , Nimmo I. A.
Published: December 2014

Theoretical time‐courses of cellular permeation by non‐electrolytes have been derived, given that the rate‐limiting step is (a) either the carrier transport or the passive diffusion of the non‐electrolyte across the cell membrane, or (b) the uniformly slow diffusion of the non‐electrolyte throughout the protoplasm. It is demonstrated that although in some circumstances the time‐courses of carrier transport and uniformly slow diffusion may be indistinguishable at any one concentration, they can be distinguished by differences in the concentration‐dependence of their parameters: the parameters of whichever hypothesis is valid are independent of concentration. The time‐courses of uptake of D‐glucose, L‐arabinose and D‐xylose by human erythrocytes are shown by this criterion to be consistent only with the hypothesis of carrier transport.
RESPIRATORY CHANGES INDUCED BY THE IMMEDIATE BLOCK OF NERVOUS CONDUCTION IN THE VAGUS NERVES
Authors: Sant'Ambrogio Giuseppe , Camporesi Enrico , Sellick Hilary , Mortola Jacopo
Published: December 2014

A differentiation of vagal respiratory reflexes has been obtained in rabbits by the application of a D.C. current of various intensities to both the vagus nerves. It has been possible to abolish the inflation reflex while Head's paradoxical response to inflation was revealed without eliminating the deflation reflex. The coexistence of Head's paradoxical reflex and the deflation reflex may suggest that these reflex responses originate through activation of the same receptors.

The inspiration which follows the immediate withdrawal of vagal afferent inflow has a much longer duration than the following ones: this seems to suggest that some of the inhibitory influence coming through the vagus is taken over, after the duration of the first breath, by some other inhibitory mechanism.

A vagal ‘block’ introduced at the same time as an occlusion of the airways leads to an inspiratory effort which is much longer than when occlusion only is performed. This could be ascribed to the blockade of some vagal fibres normally active at FRC which should have an overall inhibitory influence on inspiratory activity.
INTRARUMINAL AND SYSTEMIC RESPONSES TO VARIATIONS IN INTAKE OF SODIUM AND POTASSIUM BY SHEEP
Authors: Warner A. C. I. , Stacy B. D.
Published: December 2014

A maintenance diet providing about 200 m‐equiv potassium and 30 m‐equiv sodium per day was given to sheep; on this intake sodium and potassium balances were small and positive. When potassium chloride was added to the diet to provide a total of about 700 m‐equiv potassium per day, the potassium content of the rumen increased and the sodium content decreased, apparently due to an increased rate of absorption of sodium across the rumen wall. The rate of excretion of sodium in the urine was increased for about 4 days, giving a considerable negative sodium balance; the extra amount excreted was of the same order of magnitude as the loss from the rumen. Water consumption increased by 0·5–0·9 l./day, without change in water balance. The apparent potassium balance increased by an amount much greater than could be accounted for by changes in rumen content.

When the potassium content of the diet was returned to its initial value there was an intense retention of sodium by the kidney, with signs of increased adrenocortical activity and a strongly positive sodium balance for about 14 days. During this time the sodium content of the rumen increased and the potassium content decreased slowly to about initial values. Water consumption retumed to normal and the potassium balance dropped, often to low or even negative values for a while.

The mechanisms apparently permitting the rumen to dominate the response of the whole animal to changes in the electrolyte content of the diet are discussed.
LUNG FUNCTION AND EXERCISE PERFORMANCE OF HEALTHY CARIBBEAN MEN AND WOMEN OF AFRICAN ETHNIC ORIGIN
Authors: Miller G. J. , Cotes J. E. , Hall A. M. , Salvosa C. B. , Ashworth A.
Published: December 2014

Lung function, body muscle, levels of habitual activity and exercise performance were measured in young adult men and women of African origin in Jamaica and Trinidad. The results were compared with those of men and women of European descent studied by the same methods in Leeds, England.

Lung function was very similar in Jamaicans and Trinidadians. Vital capacity was smaller in Africans than in Europeans and smaller in women than in men, even after standardization for age and height. There was no sex difference in residual volume. The single breath transfer factor was larger in men than women but there was no ethnic difference. The effects of age and height on lung function appeared to be similar in the two ethnic groups. Exercise tidal volume relative to minute volume was larger in Europeans than in subjects in the Caribbean but this difference disappeared when allowance was made for vital capacity.

When allowance was made for differences in body muscle the heart rate during standard sub‐maximal exercise was lowest in Jamaican men and highest in Trinidadian men and Jamaican women, with English men and women intermediate. These differences may have been related to the levels of habitual activity in these groups, which were judged to have been highest in the Jamaican men.

Maximal heart rate during exercise was similar in all male groups but relative to body muscle, maximal exercise performance was impaired in the subjects in the Caribbean. It is postulated that this may have been owing to the higher temperatures in Jamaica and Trinidad than those in England.

We conclude that while ethnic and sex differences affect ventilatory capacity and tidal volume these are less important for maximal oxygen uptake than habitual activity, environmental temperature and body muscle.
THE INFLUENCE OF URETER LIGATION AND DIURESIS ON RENAL LYMPH FORMATION
Authors: McIntosh G. H.
Published: December 2014

Ligation of the ureter in sheep was followed by a 2‐12‐fold increase in lymph flow from the kidney during the first 24 hr, after which flow rates returned slowly to preocclusion levels. There was a fall in protein concentration in lymph, and a slight rise in the ratio of lymph concentration to plasma concentration of urea, potassium and magnesium. A similar rise in lymph flow was observed during the intravenous infusion of large amounts of Ringer‐Locke solution. Diuresis produced by Frusemide injections or mannitol infusion was not accompanied by any change in lymph flow.

When labelled inulin and hippuran were infused intravenously into a sheep with the left ureter ligated, the ratio of lymph concentration to plasma concentration of these substances was significantly higher than for the unobstructed kidney. When these substances were injected into the renal pelvis and the ureter ligated, higher levels were detected in lymph than in blood. However with neither substance did the amount in lymph exceed a fraction of 1% of the total injected.

It is concluded that the increase in lymph flow is attributable to haemodynamic changes involving a redistribution of blood flow within the kidney, and that reabsorption from urine in the renal pelvis is minimal.
RENAL EXCRETION OF POTASSIUM AND POTASSIUM TOLERANCE IN THE PIG
Authors: Mason G. D. , Scott D.
Published: December 2014

Young pigs given supplements of KCl in the food excreted the additional KCl in the urine indicating the importance of the kidney in the regulation of potassium excretion.

Intravenous infusion of KCl increased the concentration of potassium in the plasma and the rate of excretion of potassium in the urine. This increase was proportional to infusion rate and in some experiments the amount of potassium excreted in the urine exceeded the amount filtered at the glomerulus, demonstrating net secretion of potassium by the renal tubule. Urinary excretion of sodium was markedly increased during KCl infusion.

After pigs had been given a diet containing supplementary KCl for 6 days their ability to excrete potassium in the urine in response to intravenous KCl infusion was not altered although the sodium diuresis was much reduced.

Intravenous infusion of KCl into acidotic pigs resulted in a rise in the rate of excretion of potassium in the urine of less than half that seen in pigs in normal acid‐base balance given the same rate of infusion. Glomerular filtration rate and the amounts of potassium filtered at the glomerulus during KOl infusion were unaffected by acidosis, which suggests that the lowered excretion of potassium in urine seen in acidotic pigs was the result of reduced tubular secretion.