bluuebunny/crossref_metadata_2025_split huggingface dataset:
The secretory and vascular response to nervous and hormonal stimulation in the pancreas of the pig
Authors: Hickson J. C. D. 
Published: December 2014

1. The atropine‐resistant action of the vagus nerves on the flow of pancreatic juice in the pig has been examined and related to certain properties of the pancreas in this species.2. The pancreas was more sensitive to secretin in the pig than in the dog, although similar maximal rates of secretion were observed in both species.3. The potentiation by secretin of the effects of parasympathetic stimulation on the flow of juice was conspicuous in the pig because of the heightened sensitivity to secretin and the resistance to atropine of this action of the secretory nerves.4. Stimulation of the vagus nerves increased the output of amylase in pancreatic juice more readily than injections of pancreozymin in the pig. In the dog pancreozymin was more effective than stimulation and could alone raise the amylase output to values comparable with those attained by stimulation in the pig. In both species atropine reduced the response to pancreozymin by only 20–25%, compared with 70–95% for vagal stimulation.5. Stimulation of the vagus nerves caused an intense, well maintained vasodilatation in the pancreas, which appeared after a shorter latent period than the secretion and was not diminished by atropine. Pancreozymin caused a smaller, and secretin only a slight, increase in pancreatic blood flow, which was also resistant to atropine, but appeared at the same time as the enhanced flow of juice. Injections of acetylcholine caused a vasodilatation which preceded the secretion but was abolished by atropine. The possibility that the pancreas receives an atropine‐resistant parasympathetic vasodilator nerve supply is discussed.6. The results provide no evidence that a substance with specific secretin‐like properties might be released within the pancreas to act as a secondary transmitter for the effect of stimulation of the vagus nerves on the flow of pancreatic juice.7. The experiments indicate that differences in the parasympathetic innervation of the exocrine cells of the pancreas between the pig and dog may underlie the observed differences in the secretory responses of the gland in these species.
Bicarbonate secretion and non‐Na component of the short‐circuit current in the isolated colonic mucosa of Bufo arenarum
Authors: Carlisky N. J. , Lew V. L. 
Published: December 2014

1. In the isolated colonic mucosa of Bufo arenarum, under special circumstances, there is a variable fraction of the short‐circuit current (0–38%) that is unaccounted for by either the Na or the Cl and bicarbonate transmembrane net fluxes.2. The hypothesis that a special kind of bicarbonate transport may account for the non‐Na component of the short‐circuit current was investigated. According to this, bicarbonate ions formed within the membrane await transport towards the mucosal solution within a compartment that does not undergo isotopic exchange with the serosal bathing solution. This kind of transport may be detected by a lowering of mucosal specific activity of bicarbonate but would not be revealed by the classic method of comparing the difference between the unidirectional fluxes with the short‐circuit current.3. The specific activity of bicarbonate was determined in the inside solution (initially bicarbonate‐free) of ten normal and four everted colonic sacs incubated in an external medium (reservoir) containing a constant specific activity of bicarbonate. Comparison between membrane‐to‐internal solution bicarbonate flux and non‐Na component of the short‐circuit current was carried out in two different ways: (a) by measuring the remaining short‐circuit current in Na‐free medium and (b) by determining simultaneously the Na net flux.4. Whatever the value of the short‐circuit current and its non‐Na component, there is no reduction of the specific activity of the bicarbonate appearing in the inside solution of the everted colonic sacs.5. In the normal sacs there is a reduction of the specific activity of bicarbonate which accounts for a membrane‐to‐mucosa bicarbonate flux which parallels the variations of the non‐Na component of the short‐circuit current although quantitatively representing only 68–87% of it.6. There is no systematic decrease in the rate of reduction of the mucosal specific activity of bicarbonate in successive experimental flux periods; this excludes a slow equilibration of the intracellular bicarbonate with serosal bicarbonate.7. Other possible explanations of the present results are discussed, as well as the availability and hydration rate of metabolic CO2 necessary to account for this kind of bicarbonate transport.
Forearm vasodilatation following release of venous congestion
Authors: Caro C. G. , Foley T. H. , Sudlow M. F. 
Published: December 2014

1. The volume rate of forearm blood flow was measured with a mercury‐in‐rubber strain gauge, or with a water‐filled plethysmograph, from 1 sec after termination of a 2‐3 min period of venous congestion.2. When congesting pressure had been less than 18 mm Hg, average post‐congestion flow (five subjects) was constant during approx. 10 sec and not significantly different from resting flow.3. When congesting pressure had been 30 mm Hg, average post‐congestion flow (eight subjects) was 26% higher than resting, during 3‐4 sec after release of congestion, but rose to 273% of resting during 4‐6 sec after release of congestion.4. In other studies forearm vascular resistance had been found normal or increased during such venous congestion, and theoretical studies here indicated that passive mechanical factors could not account for the delayed occurrence of high post‐congestion flow.5. It appears, therefore, that the forearm vascular bed dilates actively shortly after release of substantial venous congestion. It would seem more likely that a myogenic mechanism, rather than a metabolic one, is responsible.
The coupling of downhill ion movements associated with reversal of the sodium pump in human red cells
Authors: Lant A. F. , Priestland R. N. , Whittam R. 
Published: December 2014

1. Previous work on the incorporation of inorganic phosphate (Pi) into ATP has suggested reversal of the chemical reactions of the Na pump in human red cells. A study has now been made of the associated movements of Na and K.2. The efflux of K, and the influx and efflux of Na were measured. When the Ringer was without K, the loss of cell K was inhibited by ouabain, and the ouabain‐sensitive component of K efflux (0·36 μ‐equiv.ml.−1.hr−1) required external Na.3. The exchange of Na was also inhibited by ouabain. When influx and efflux of Na were measured simultaneously in K‐free Ringer there was an excess of ouabain‐sensitive influx over efflux of about 0·36 μ‐equiv.ml.−1.hr−1. This difference balanced the ouabain‐sensitive K efflux, and was not found with 10 m
M‐external K. The Na and K movements appear to be coupled and to be mediated by reversal of the Na pump.4. The net uptake of Na sensitive to ouabain was 0·38 μ‐equiv.ml.−1.hr−1 for red cells incubated in K‐free Ringer, and the net loss of K under the same conditions was 0·58 μ‐equiv.ml.−1.hr−1 in rough keeping with the unidirectional flux values.5. Oligomycin decreased Na influx and efflux to the same extent as ouabain.6. There appears to be a coupled downhill movement of Na and K that is abolished both by inhibitors of the Na pump and by external K which promotes normal transport of Na outwards and K inwards.
The secretory pattern of three stomach preparations in the rat
Authors: Svensson S. E. 
Published: December 2014

1. In conscious rats provided with a gastric fistula, or a Pavlov pouch, or a Heidenhain pouch, the secretion of acid and pepsin was studied in the interdigestive state and in response to hog gastrin II. In Pavlov pouches and in Heidenhain pouches the responses to 2‐deoxy‐
D‐glucose and to food were established, as were also the responses to gastrin pentapeptide and methacholine in Heidenhain pouches.2. Interdigestive secretion of acid and pepsin is substantial in the gastric fistula and the Pavlov pouch preparation, whereas in the Heidenhain pouch acid secretion is low or scanty, and the ratio pepsin/acid output is higher than in the innervated preparations.3. Feeding evoked secretion of acid and pepsin in the Heidenhain and Pavlov pouches; the increase in pepsin secretion lasted much longer in the Heidenhain than in the Pavlov pouch.4. Methacholine, infused in a threshold dose, augmented the acid output in response to food in the Heidenhain pouch, but did not affect the pepsin output.5. Gastrin II (hog) evoked graded acid responses in the three stomach preparations, and the innervated preparations were more sensitive to gastrin II than the denervated one, whereas stimulation of pepsin secretion was apparent only in the Heidenhain pouch.6. Methacholine, on infusion, in the Heidenhain pouch, gave a maximal acid secretory response, greater than twice that obtained by gastrin, and produced strong stimulation of pepsin.7. Methacholine, infused in a threshold dose, accentuated the acid secretory response to graded doses of gastrin.8. 2‐deoxy‐
D‐glucose stimulated acid and pepsin secretion consistently in the Pavlov pouch, whereas in the Heidenhain pouch the response was scanty or absent.9. A large dose of gastrin pentapeptide injected intravenously while a background secretion was maintained by gastrin II, produced in the Heidenhain pouch triphasic changes in the sequence: stimulation, inhibition, stimulation.
Reversal of the potassium entry mechanism in red cells, with and without reversal of the entire pump cycle
Authors: Glynn I. M. , Lew V. L. , Lüthi Ursula 
Published: December 2014

1. 42K has been used to study the ouabain‐sensitive component of potassium efflux from intact human red cells.2. Ouabain‐sensitive efflux of potassium was observed only in media containing either sodium ions in moderate or high concentration or potassium ions.3. The effects of sodium and potassium in the medium were not additive. Potassium ions always increased the ouabain‐sensitive potassium efflux, but in media containing 4·2 m
M‐K an increase in sodium concentration from 4·5 to 131 m
M had little effect.4. In potassium‐free media, ouabain‐sensitive potassium efflux increased roughly linearly as the external sodium concentration was increased from 35 to 155 m
M.5. The sensitivity of potassium efflux to external potassium depended on the concentration of sodium in the medium. In a 5 m
M‐Na (choline) medium, ouabain‐sensitive potassium efflux was half‐maximal at about 0·27 m
M‐K. In a 150 m
M‐Na medium the effect of potassium was half‐maximal at about 1 m
M‐K. The relation between external potassium concentration and ouabain‐sensitive sodium efflux was similarly influenced by the concentration of sodium ions in the medium.6. Inosine greatly reduced the ouabain‐sensitive efflux of potassium into both 5 m
M‐K and potassium‐free media. It probably acted by reducing the intracellular phosphate concentration to a low level.7. Ouabain‐sensitive potassium efflux was not affected by the concentration of inorganic phosphate outside the cells and was not associated with a ouabain‐sensitive efflux of phosphate of comparable magnitude. A small associated efflux could not be excluded.8. Simultaneous measurements of sodium efflux and of potassium efflux from identical batches of cells incubated in potassium‐free media showed that inosine reduced ouabain‐sensitive potassium efflux at the same time as it increased ouabain‐sensitive sodium efflux.9. When cells that had been largely depleted of energy stores by pre‐incubation with 2‐deoxyglucose were incubated in high‐sodium media, with and without potassium, it was observed that potassium in the medium increased the ouabain‐sensitive potassium efflux but reduced the ouabain‐sensitive efflux of sodium.10. Simultaneous measurements of the ouabain‐sensitive efflux of potassium and influx and efflux of sodium across the membranes of starved cells incubated in potassium‐free media, with and without inosine, suggested that ouabain‐sensitive potassium efflux was associated with a net ouabain‐sensitive entry of sodium.11. The results are best explained by supposing that the ouabain‐sensitive efflux of potassium does not reflect lack of discrimination by the mechanism responsible for sodium expulsion, but is brought about by the reversal of steps in the pump cycle normally responsible for potassium entry.
Synthesis of adenosine triphosphate at the expense of downhill cation movements in intact human red cells
Authors: Glynn I. M. , Lew V. L. 
Published: December 2014

1. When red cells that have been starved for about 6 hr are loaded with inorganic phosphate and incubated in high‐sodium potassium‐free media, the ouabain‐sensitive efflux of potassium from the cells is accompanied by a ouabain‐sensitive incorporation of inorganic phosphate into ATP.2. The magnitude of the incorporation varies roughly linearly with the concentration of sodium in the medium. The ratio (ouabain‐sensitive potassium efflux)/(ouabain‐sensitive ATP synthesis) is probably not much less than 2 nor much greater than 3.3. Potassium in the medium inhibits the ouabain‐sensitive incorporation of phosphate. The concentration of potassium necessary for half‐maximal inhibition is about the same as the concentration at which, under similar conditions, ouabain‐sensitive potassium influx and the stimulation of ouabain‐sensitive potassium efflux are both half‐maximal.4. These observations suggest that the ouabain‐sensitive efflux of potassium from red cells incubated in high‐sodium potassium‐free media is associated with a reversal of the entire pump cycle. In media containing sufficient potassium to saturate the pump, the efflux appears to involve the reversal of only part of the cycle.
The effect of an intrauterine thread on tissue changes in the endometrium of the pseudopregnant rat
Authors: Wood J. C. 
Published: December 2014

1. Changes in the fresh weight of uterine horns bearing unilateral intrauterine threads have been measured during early pseudopregnancy in the rat.2. Such a thread, which acts as an intrauterine contraceptive device, causes an increase in weight in the horn which carries it, compared to the untreated contralateral horn, on days 2, 4, 5 and 7 of pseudopregnancy. This increase is observed when the device has been present either for 25 or for 45 days.3. The fresh and dry weights of samples of endometrial tissue together with the concentration of chloride and potassium in these samples have also been determined, both in control horns and in horns which have contained a device for 45 days.4. The fresh and dry weights of samples from the device side are greater than the control. However, the weights of the endometrial samples recovered showed considerable variation, particularly in the device side. The weight of water per unit dry weight of endometrial tissue remains constant in the control side but falls steadily from day 2 to day 7 in the device side. The extracellular fluid space, as measured by the weight of chloride per unit dry weight, follows a similar pattern in each side. The weight of potassium per unit dry weight of control tissue falls on days 4 and 5 but rises again on day 7. By contrast, the potassium content of endometrial tissue from the device side falls steadily, reaching its lowest value on day 7.5. These results suggest that the presence of an intrauterine thread alters the composition of the connective tissue matrix of the uterine endometrium. It is likely that these changes are partially responsible for the contraceptive action of such a foreign body.
The rates of release and binding of thyroxine by bovine serum
Authors: Hillier A. P. 
Published: December 2014

1. Estimates have been made of the rates of release and binding of thyroxine by bovine serum proteins. The method involves measuring the rates at which columns of Amberlite resin take up thyroxine from serum.2. At 37° C the dissociation rate (the rate of release of bound thyroxine into free solution) is about 2·2% sec−1.3. The binding of thyroxine by serum is a complex process, the majority of the hormone being ‘loosely’ bound within 0·1 sec but the over‐all process taking some 20 sec to completion.4. A mechanism is proposed for the uptake of thyroxine by the liver. It involves a simple competition between the plasma and the liver binding sites for the free thyroxine released into solution by the dissociation reaction.
Effects of fasting on intestinal transfer of sugars and amino acids in vitro
Authors: Newey H. , Sanford P. A. , Smyth D. H. 
Published: December 2014

1. Transfer of sugars, amino acids and fluid and metabolism of glucose were studied with everted sacs of small intestine prepared from fed and 3‐day fasted rats.2. In the absence of glucose there was some evidence for increased intestinal transfer of sugars and amino acids in fasted animals. In the presence of glucose there was in general decrease in transfer of amino acids and fluid.3. In fasted animals glucose transfer was reduced except in the lower ileum, and there was a general reduction in glucose metabolism.4. Because of the large reduction in gut weight in fasted animals, expressing transfer on a weight basis is considered not to be a valid procedure in studying the effects of fasting on intestinal transfer.5. The results have been discussed in relation to effects of fasting on energy availability, efficiency of transfer mechanisms, permeability of the intestine and the value of in vitro methods in the study of physiological absorption.
The effect of hypoxia, hypercapnia and hypotension upon carotid body blood flow and oxygen consumption in the cat
Authors: Purves M. J. 
Published: December 2014

1. Carotid body blood flow (c.b.f.), the arterio—venous oxygen (A—V O2) difference and oxygen consumption were measured in forty‐seven cats, anaesthetized with pentobarbitone, paralysed with gallamine and ventilated artificially. Carotid sinus and cervical sympathetic nerves were intact throughout.2. A system for perfusing the carotid body artificially with blood is described and evidence is given which shows that similar results were obtained whether the carotid body was naturally or artificially perfused.3. With arterial pressure, blood gas tensions and pH within physiological limits, c.b.f. varied between 33 and 68 μl./min, average 41·5; A—V O2 difference between 0·21 and 0·46 ml./100 ml., average 0·34, and calculated oxygen consumption between 0·115 and 0·195 μl. O2/min, average 0·147.4. With constant mean arterial pressure, hypoxia (30–40 mm Hg Pa, O2) or hypercapnia (> 50 mm Hg Pa, CO2) resulted in a small increase of c.b.f., up to 14 μl./min above control; an average fall of A—V O2 difference by 49% of control and an average fall of oxygen consumption by 36% of control.5. Carotid body blood flow fell linearly with mean arterial pressure over the range 100–170 mm Hg, the slope of the curve varying between 0·78 and 1·22 μl. min−1. mm Hg−1.
M.A.P. A—V O2 difference was unaffected so that oxygen consumption fell in proportion to c.b.f.6. It is concluded that the unique response of the carotid body to these stimuli is a fall in oxygen consumption and that this bears a closer relation to the known pattern of chemoreceptor discharge than do changes in total blood flow.
The role of the cervical sympathetic nerve in the regulation of oxygen consumption of the carotid body of the cat
Authors: Purves M. J. 
Published: December 2014

1. Carotid body blood flow (c.b.f.) and carotid arterial—carotid body venous oxygen (A—V O2) difference were measured and carotid body oxygen consumption calculated in twenty‐six cats anaesthetized with pentobarbitone sodium, paralysed with gallamine triethiodide and ventilated mechanically.2. With the sinus nerves intact and with blood gas tensions and carotid sinus pressure within physiological limits, section of either the pre‐ or post‐ganglionic cervical sympathetic nerve on the same side caused an average rise in c.b.f. of 9·2 μl./min, in A—V O2 difference of 0·09 ml./100 ml. and in carotid body oxygen consumption of 0·075 μl./min.3. When the pre‐ or post‐ganglionic cervical sympathetic nerves were stimulated, c.b.f. and A—V O2 difference fell. The fall in c.b.f. was enhanced at high Pa, CO2; the fall in A—V O2 difference and in calculated oxygen consumption was enhanced at low mean arterial pressure (
M.A.P.) or Pa, O2.4. Following sympathectomy, a reduction of
M.A.P. at constant Pa, O2 and Pa, CO2 caused a fall in c.b.f. and a commensurate rise in A—V O2 difference so that carotid body oxygen consumption remained approximately constant.5. When Pa, O2 was altered over the range 35 to > 400 mm Hg, or Pa, CO2 over the range 27–70 mm Hg at constant
M.A.P., c.b.f. changed by amounts which were similar to those observed when the sympathetic nerves were intact and A—V O2 difference changed in the opposite direction so that carotid body oxygen consumption similarly remained constant.6. Comparison of these results with those observed when the sympathetic nerves were intact indicates that the sympathetic nerves exert a vasoconstrictor effect upon carotid body blood vessels over a wide range of blood gas tensions and arterial pressure and that they also tend to diminish the rate of carotid body oxygen consumption. The mechanisms which may be involved in this regulation are discussed.
Interaction of cortical evoked potentials in the rat
Authors: Holmes O. , Short A. D. 
Published: December 2014

1. Unitary and mass potentials were recorded with glass micropipettes at different depths in and around the primary somatosensory area of the cortex in rats anaesthetized with urethane; in addition, surface mass potentials were recorded with chlorided silver ball electrodes. Potentials were evoked by stimuli to the contralateral forepaw and the contralateral cortex. Observations were confined to potentials evoked within 20 msec of stimulation.2. If forepaw stimuli were applied at times when the cortex was not showing spontaneous activity, one component of the evoked response was a widespread depth negativity. This was accompanied by a smaller surface positivity which had the same time course. It could be recorded over the same area of cortex. Unitary activity was found with the same latent period and spatial distribution as the depth negativity. These components of the evoked mass and unitary responses to forepaw stimulation were absent if times of spontaneous cortical activity were chosen for delivering the stimuli.3. Contralateral cortical stimuli evoked mass activity similar to the component of the mass response to forepaw stimulation described in 2. Stimuli given simultaneously to the two sites elicited less unitary activity than the sum of the unitary activity evoked by the two stimuli separately. The mass activity exhibited the interactions which would be expected on the hypothesis that it is generated by the unitary activity. The time course of the interaction is described.4. The interaction was confined to the components of the evoked potentials which were only present if stimuli were applied when the cortex was quiescent. Stimuli applied when the cortex was active evoked mass and unitary potentials which showed no interaction.