Amount Of Total Sugars Research Articles

Evaluation of fruit quality in peach and apricot

The fruits of nine white-fleshed and three yellow-fleshed peaches, one white-fleshed nectarine and five apricot cultivars were compared as to chemical composition and sensory evaluation. Three acids (succinic, malic and citric) and eight sugars (xylitol, fructose, glucose, mannose, sorbitol, inositol, sucrose and maltose) were identified. The total amount (mg/100g FW) of acids ranged from 300 to 1,500 in peach and from 2,900 to 4,600 in apricot. The total amount of sugars ranged from 6,700 to 12,500 and from 7,400 to 10,800 for peach and apricot respectively. Total phenolics were very varia- ble, ranging from an average of 30 mg/100g FW in the yellow-fleshed peaches to values two-seven fold higher in the white ones and from 27 to 91 in apricots. According to the sensory and chemical evaluations conducted in this study, acceptable or good flavor should match the following composition (mg/100g FW). Peach: 1,000-1,600 organic acids, 8,500-13,000 alcohol- soluble sugars, 7.8-8.5 acid-sugar ratio; less than 80-90 phenolics. Apricot: 3,500-4,500 organic acids, 10-12,000 sugars, 2-3.5 sugar/acid ratio, less than 60 phenolics. The present study also suggests that sugar and acid patterns of fruit flesh may be useful in cultivar characterization.

Use of Heat-shrinkable Plastic Film to Extend Shelf Life of ‘Russet Burbank’ Potatoes

Abstract Freshly harvested ‘Russet Burbank’ potatoes (Solanum tuberosum L.) were individually wrapped in heat-shrinkable polymer film and stored for 12 weeks at 8C, 24C, and room temperature (RT), which ranged from 22 to 25C. Film-wrapped potatoes in Cryovac D 950, Cryovac D 955, and Dupont EHC 75 stored at 24C or RT lost less fresh weight than the nonwrapped controls. Wrapped potatoes lost 5% to 7% of their initial fresh weight when stored at RT for 12 weeks, compared to 26% for nonwrapped potatoes. Potatoes wrapped in Cryovac D 955 and stored at RT lost less ascorbic acid and starch and accumulated smaller amounts of total sugars. Lack of major change in the physical, chemical, or physiological characteristics of individually shrink-wrapped potatoes stored at warm temperatures, especially when compared to the nonwrapped controls, suggests that this is a suitable packaging technique for maintaining potato quality.

Identification and seasonal changes of glucose, fructose and mannitol in relation to oil accumulation during fruit development in Olea europaea (L.)

The amounts of glucose, fructose and mannitol, the main sugars in olive fruits, were determined in ‘Kadesh’, ‘Uovo di Piccione’ and ‘Manzanillo’ which have 8, 15 and 20% oil, respectively, at full black maturation. The sugars were separated by high-pressure liquid chromatography and characterized by ultraviolet detection after derivatization with nitrobenzoate. The total amount of sugar in ‘Kadesh’ was more than double that in the two other cultivars. A parallel rise in oil and sugar levels was noticed at the beginning of the fruit ripening period of ‘Kadesh’, while the sugar level of the other cultivars decreased during most of that period. Glucose was the predominant sugar in all cultivars, followed by fructose and mannitol. The relative amounts of mannitol were only 2% in ‘Kadesh’ and 10% in ‘Manzanillo’ and ‘Uovo de Piccione’. It is suggested that mannitol levels and oil accumulation are related.

トマトの乱形果発生と茎頂部の内生ホルモン及び栄養との関係並びに乱形果発生の制御

The levels of endogenous hormones and nutrients in shoot apices of tomato plant were compared between the seedlings exposed to high and low temperature conditions in relation with occurrence of fruit malformation. The amounts of total sugar, total nitrogen, proteinous nitrogen in the seedlings grown at low temperaturecondition were greater than those in the seedlings grown at high temperature condition. The low level of auxin and high level of gibberellin were noticed in the seedlings grown under low temperature condition.Nutritional restrictions reduced occurrence of fruit malformation by decreasing ovary split rather than oblate and triangular shaped fruits. The treatment combined with auxin spray and nutritional restrictions reduced the occurrence of both ovary split and oblate/triangular shaped fruits.

High performance liquid chromatographic determination of soluble carbohydrates in commercial drinks

AbstractHigh performance liquid chromatography was carried out to determine the soluble sugar content in canned soft drinks and commercial fruit juices stored in different types of containers. The total amount of sugars ranged from 9.2 to 13.5 g 100 ml−1 for the soft drinks, 10 to 14 g 100 ml−1 in fruit nectars and 3 g 100 ml−1 in tomato juice. The individual sugar content of soft drinks varied between different batches, although the total amount remained fairly constant for each kind of drink or juice. Only in tomato juice where sucrose was not present, did the values for glucose and fructose remain constant.

Sugar Content, Acidity and Effect on Plaque pH of Fruit Juices, Fruit Drinks, Carbonated Beverages and Sport Drinks

The concentration of fructose, glucose and sucrose, the pH and the titratable amount of acid were analyzed in the following groups of soft drinks (8–11 samples per group): (1) fruit juices, (2) fruit drinks, (3) carbonated beverages and (4) sport drinks. Moreover, the effect of representative products on pH changes of dental plaque was studied in two groups of teenagers with 16 or 19 subjects per group. The fruit juices, fruit drinks and carbonated beverages contained, on average, a total amount of sugars (fructose + glucose + sucrose) of 9.3–9.8%. The corresponding value for sport drinks was 4.4%. The sucrose content was high in 1-week-old fruit drinks and carbonated beverages, but decreased, by spontaneous hydrolysis, to relatively low values when stored at room temperature for 5 months. The mean pH values in the various soft drinks varied between 3.1 and 3.6. Fruit juices had the highest titratable amount of acid, approximately 2–3 times higher than the three other groups of products. Mouth rinses with orange juice, orange drink and Coca-Cola® resulted in low and about the same plaque pH. The sport drinks (Gatorade® and Pripps Pluss®) induced also low plaque pH values but somewhat less than the other products (p < 0.01). When Coca-Cola was consumed either from a glass or with a straw, the pH decrease was significantly smaller compared to a mouth rinse with the same product (p < 0.001). To conclude, the results from the present investigation indicate that commonly used soft drinks, i.e. fruit juices, fruit drinks, carbonated beverages and sport drinks, have about the same ‘cariogenicity’ as far as the total amount of sugars, acidity and the effect on plaque pH are concerned.

Soluble root exudates of maize: Influence of potassium supply and rhizosphere microorganisms

Maize was grown for 36 days in solution culture with roots either under axenic conditions or in the presence of rhizosphere organisms. In other experiments with sterile roots the plants were grown with different concentrations of potassium. At the end of the experiments sugars, organic acids and amino acids in the nutrient solutions were determined. Under axenic conditions the exudates consisted of up to 65% sugars, up to 33% organic acids and only up to 2% amino acids. The same substances were detected in non-sterile nutrient solutions. In the presence of microorganisms fructose, arabinose and the predominating glucose decreased to almost one half, while sucrose was not affected. The amounts of organic acids were not changed by microbial growth. The main amino acid, glutamic acid, was nearly doubled by the presence of microorganisms, whereas other amino acids remained unchanged. The lower O 2 content of the nutrient solutions of non-sterile roots suggested microbial decomposition of monosaccharides. In another experiment with roots grown under axenic conditions and with different K treatments low K supply significantly increased the total amounts of sugars, organic acids and amino acids exuded g −1 root dry matter. As in the previous experiment glucose, fumaric and oxalacetic acid as well as glutamic and aspartic acid dominated in the respective fractions. Again sugars and organic acids represented the major quantity of exudates, while amino acids amounted to less than 2%. In an additional experiment with another cultivar, with nitrate as N source and a 5-day longer growth period, somewhat different results were obtained. In the exudates sugars were found in lower amounts, probably due to a higher growth rate. Under these conditions organic acids were the prevailing root exudates. Unlike sugars and amino acids, their total quantity was not affected by K nutrition, but the proportion of malic acid increased with increasing K supply, while oxalacetic acid dominated at low K nutrition. Similarly the total amount of organic acids within the root was independent of K nutrition. However malic acid content increased with increasing K application, while the likewise dominating citric and oxalacetic acid decreased.

Chemical studies of dissolved carbohydrates in seawater

Charcoal column chromatography and a dialysis system using a Visking tube were used for the concentration and separation of dissolved carbohydrates in seawater. Recoveries of mono-, oligo-, and polysaccharides were 46–74, 61–89 and 70%, respectively, relative to the total amount of sugars initially submitted to analysis. The combined charcoal column chromatography and dialysis system was used to separate dissolved carbohydrates in seawater samples from Mikawa Bay into mono-, oligo- and polysaccharide fractions. The polysaccharides are separated into two fractions with molecular weights of <4,000 and >4,000 using Sephadex G-25 column chromatography. Monosaccharides, oligosaccharides, polysaccharides with M.W.<4,000 and polysaccharides with M.W. >4,000 accounted for 7–9, 15–26, 7–13 and 20–33% of total dissolved carbohydrates, respectively. However, 32–38% of dissolved carbohydrates were lost during the analytical procedures. Glucose, galactose, mannose, xylose, arabinose, ribose, fucose, and rhamnose were found upon acid hydrolysis of the oligo- and polysaccharide fractions, while fucose and rhamnose were not present in the monosaccharide fraction. Possible sources of the carbohydrates in these fractions are discussed with reference to the monosaccharide composition of cellular carbohydrate in marine algae.

Studies in Forest Pathology

AbstractA survey for the parasitic alga. Cephaleuros virescens Künze in relation to its seasonal distribution in different forest types has been done. The alga was absent in gymnosperms and was common in angiosperms. The disease severity was more in summer and the rainy season and absent in winter, Combretum decandrum was found to be most susceptible to this parasite alga. Altogether 49 hosts were recorded out of which 26 were new host records. Healthy leaves contain higher amounts of total nitrogen and total phenol, whereas in algal infected leaves the amounts of total sugar, total amino acid and dry weight were higher.

Role of Energy in Pathogenic Variability of Pyricularia oryzae

Abstract Pyricularia oryzae Cav. reacts differently to different varieties. IB race group attacked Zenith for three consecutive years for both rabi and kharif seasons under artificial inoculation condition. Three different isolates were obtained in IB race which differed in their pathogenicity giving a constant susceptible reaction to Zenith. The difference in energy potential of three isolates of P. oryzae was tested biochemically. Total sugar, protein and protein patterns were studied following modern methods. W isolate contained maximum amount of total sugar (18.3 μg/g), total protein (23.8 μg/g albumin equivalent) and seven distinct protein bands on polyacrylamide disc electrophoretic gel which was directly correlated with maximum infection value. So it was concluded that the aggressiveness of P. oryzae depends on its energy potentiality in terms of total protein and protein patterns.

ERZURUM, KARS, ERZİNCAN ve GÜMÜŞHANE İLLERİNDE YETİŞTİRİLEN ÖNEMLİ ELMA ÇEŞİTLERİNDEN ASKORBİK ASİT KATILARAK ELDE EDİLEN ELMA SULARININ AMBARLANMASI SIRASINDA BÜNYELERİNDE MEYDANA GELEN KİMYASAL ve FİZİKSEL DEĞİŞMELER ÜZERİNDE ARAŞTIRMALAR

OZET Bu arastirma, degisik uretim asamalarinda askorbik asit (C vitamini) kattlmis o/an/ar ile, katk1siz elma sularinin, oda sicakliginda ve buzdo/abll1da alti ay sure ile ambarlaninalari sirasmda, top/arn polifenol, askorbik asit, titre edilebilir asitlik, pH, sakkaroz, top/arn ve indirgen seker, toplam kuru madde ile renk .yonunden ugradik/ari degismeleri saptamak amaciyla yapi/mistir. Materyalolarak. Erzurum, Kars, Erzincan pe Gumushane illerinin elma yetistiriciligi yonunden onemli yorelerinde, b~hcede agaclarindan yeme olgunlugunda toplanan Amasya, Golden, Cam, Karadacik, Ak saki, Gobek ve Sinan elma cesitlerinden; elmalar parcalanir parcalanmaz 100 kg cibreye /00 g, pastodzasyondan hemen once 100 kg siraya 100 guzerinden askorbik asit katilarak elde edilen elma ~ulari i'e askorbik asit katdrnadan elde edilen elma sulm i kul/anilmistlf. Toplam polifenol .nicelikleri ambarlama suresince aitma ve aza/ma bicimiminde da/galanmalar gostermistir. Askorbik asit katkili elma sularinin polifenol miktarlari katkisizlardari daima· yuksek bulunmustur. A.~lwrbik asit kattlmadan islenen elma su/arrnin askorbik asil du' zeylerinin cok dusuk oldugu ve 2 aylik ambar/ama sonunda nicel o/arak belirlenemiyecel<. kadar azaldigi saptanmistir. Askorbik asit katkili elma sulannda askorbik asil kaybinin daha cok ilk 2 ay icinde oldugu belirlenmistir. Ambarlamanm ilk 2 ayinda onemli aialma gosteren titre edi/ebi/ir asit nicelikleri bundan sonra 6. ay sonuna kadar dec~ismemistir. Indirgen seker J1rcelikl~1 inin ambadama siiresince yukseldigi, bu durumun oda sicakliginda daha belirgin oldugu saptanm(Jtlr: SlikkaJ'oz duzeyleri ambarlama suresi boyunca azaldi.~i halde, sakkGl'oz ve indirgen seker toplami olan toplam seker deg;.smemistir. Ozellikle, elmalarm parcalanmasindan hemen sonra askorbik asit katilan elma sularinm renklerinin, ambartarna siiresince katklSlzlarinkinden cok daha acik kaldigi saptanmistir. SUMMARY INVESTIGATONS ON THE CHEMICAL AND PHYSICAL CHANGES OCCURING DURING THE STORAGE OF APPLE JUICES WHICH WERE MANUFACTURED WITH THE ADDiTON OF ASCORBiC AClD FROM THE iMPORTANT APPLE 'VARiETES GROW'iNG iN PROVINCES OF ERZURUM, KARS, ERZiNCAN AND GUMUSHANE This research has been inade to find out the changes accuring in same chemical and physi.cal proterties, of apple juices with or without addition of L- ascorbic acid i tl different processing steps, during six rnon.ths of st0rage in two diITerent temperatures. Apple juices obtained from the varietIes of Amasya, Golden. Cam Karadacik, Ak Sak. Gobek and Sina~ wliich were harvested from main apple growing districts of Erzurum, Kars Erzincan and Gumiishane pro vinces, were used in this expeiiinenL The experimental inaterials each apple variety were prepared as follow: 100 g ascorbic was added to 100 kg pulp inimediately after grindil1g;, _._- 100 g a~corbic acid was added to 100 kg juice just before their pasteurization.: -No ascorbic ,acid was during processing (control). All sample~ were ira nsfered into the colored bottle and pasteurized. After the pasteurization, half of the sainples e<ich treatment 16 were kept in a refrigerator and the other half kept at the room temparature for six months. The t'oHowing re,ulb have been obtained: i. it has been found out that the ascorbic acid conlent of apple .iuices proc.: essed without addition of ascorbic acid were 100 Jow, 2. The main decrease in the ascorbic acid content of fortified sainples has been seen in the fjrst 2 months, After this period decrease is not significant. Lower ascorbic acid content was found in the jucics prepared w'ith the <iddition of asorbic acid in early stages of processiug (i.e. just after ,gri iidi ng) than jucies prepared ,,;'ith the addition of ascorbic acid in later stages of processing U.e, jiist before pasteurization). 3. The polyphenol content of apple jucices obtained from different varieties was also difl'erent. Although the inflLlence of the processing steps which ascorbic acid was added on the po'yphenol amouiit is not significant, greater polyphenol content was found in fortified jucies. 4. Different titratable acidity was fourid for each vadeties. In the nrst two months of starage there were significant decreases in titratable acidities, after that period any chal1~ ge was not occured. Addition of ascorbic acid iIlcreased the acidity of apple jl:lIces significantly. 5. The amount of reducing sugar increased through the storage period. This was more prominent at room temperature starage eonditions. The redl.!ciiig sugar content of the varieties were different. Different. amounts of total sugar are found in varieties as their natural characteristics. 6. The color of apple juices mesaured by yellow and red color values of Lovibond Tintometer was different for each variety. The addition ascorbic acid to the pulp effected the color of juices and the lowest Lovibond color values obtained from these samples. The samples obtained by addition of ascorbic a«id just before pasteurization showed darker color than above treat· ment and samples without ascorbic acid gave the darkest color of all,

Effects of Defoliation, Gibberellic Acid and 4-Chlorophenoxyacetic Acid on Growth and Composition of Thompson Seedless Grape Berries

Fifty percent defoliation at berry shatter significantly reduced berry weight of Thompson Seedless grapes. Either gibberellic acid (GA₃) or 4-chlorophenoxyacetic acid (4-CPA) applied to foliated vines produced significantly heavier berries than the control (no defoliation or hormones). GA₃ applied to 50% defoliated vines at berry shatter yielded berries similar in weight to those from control vines, whereas, 4-CPA applied to similar vines had little effect on increasing berry weight. The barley endosperm bioassay of gibberellin (GA)-like substances revealed higher activity in berries from control vines than in berries from defoliated vines sampled one week after berry shatter. GA-like activity in young berries increased in response to exogenous GA₃ application in both control and 50% defoliated vines. No measurable GA-like activity was detected in berry samples collected at véraison. Defoliation reduced the total amount of sugar (total soluble solids) per berry, but not the concentration of total soluble solids. GA₃ and 4-CPA, on the other hand, significantly increased the total sugar per berry, but markedly reduced the level of total soluble solids. The concentration of arginine in mature fruit was significantly less in defoliated vines than control vines, whereas, the levels of malate, tartrate and proline did not differ significantly between these two treatments. GA₃ and 4-CPA significantly increased the level of malate in mature fruits, but reduced the concentrations of proline compared to control fruits. The concentrations of tartrate and arginine in berry juice from vines treated with GA₃ or 4-CPA did not differ significantly from control fruits.

日本ナシ果実の硬化障害に関する研究

The relationship between the levels of nutrients and the various degrees of the disordered fruit of Nijisseiki pear, were studied by chemical analysis of the fruits. The results obtained are as follows:1) Phosphorus content increased while total nitrogen and calcium contents tended to decrease as the disease progressed. It seemed that this physiological disorder became apparent when calcium content fell to a level of 0.047% or less, based on dry weight.2) The amounts of total sugars, reducing sugars and fructose in affected fruits were lower while the amounts of glucose and starch were higher than those in normal fruits. In particular, fructose content showed a remarkable change proportionally with the degrees of disorder, but glucose content increased only slightly.3) A significant positive correlation was observed between total nitrogen content, and total sugars, and reducing sugars or fructose contents, between calcium content, and total sugars or fructose contents, whereas a significant negative correlation was found between total nitrogen content, and glucose or starch contents, between calcium and starch contents. No correlation was found between calcium and glucose contents.4) From the results of principal component analysis and multiple regression analysis, it is concluded that the degree of ‘yuzuhada’ disorder is characterized by a decrease in calcium absorption accompanied by changes in sugar composition in affected fruit. In particular, fructose content is remarkably lower for affected fruits than for normal ones.

Calcium concentration and the exudation of sugars from pegs and fruits of axenic peanut plants

Higher populations of total fungi, bacteria and actinomycetes occur in the geocarposphere of peanuts than in bulk soil. One of the factors that affects exudation of organic substrate is Ca 2+ concentration in the pegging medium. Plants of Arachis hypogaea L. cv. Argentine were grown axenically and the effect of three concentrations of Ca 2+ on exudation of sugars from excised fruits at different stages of development was measured. The amount of total sugar exuded was greatest at 10 mg Ca 2+ 1 −1 in the bathing solution after 48 h. More sugar was exuded from peg sections than from older fruits and the difference depended upon whether results were expressed as mg sugar g −1 fruits or μg per fruit. Of the three sugars exuded the quantities decreased in the order sucrose, fructose, and glucose.

Diabetic Management-Reply

In Reply .—We agree with Dr Finkelstein that measurements of urine reducing glucose concentration may provide different information than that indicated by the total amount of reducing sugar excreted in random specimens. Measurement of the volume of random urine specimens, however, has not been previously recommended in the management of clinical diabetes. Indeed, we are unaware of any published data indicating that measurement of the total amount of sugar excreted in random urine samples improves the value of the tests or the ability to manage diabetes. It is suggested by Dr Finkelstein that, if knowledge of the total quantity of glucose in each of several random urine samples allowed any doubt about the appropriate management of a child with diabetes, the collection of urine for 24 hours to determine total glucose excretion would correct that difficulty. In an earlier report 1 we found that the 24-hour excretion of glucose not

Developmental Physiology of Sugar Beet: I. THE INFLUENCE OF LIGHT AND TEMPERATURE ON GROWTH

Sugar beet plants were grown for 12 weeks from emergence in growth rooms at temperatures of 10, 17, 24 and 31 °C and 20, 50, 80, and 110 cal visible radiation cm-2d-1, and the changes with time in their dry weight, leaf area, leaf numbers, and storage root sugar determined. The first stage of growth was dominated by the development of the shoot, but the storage root gradually assumed increasing importance and eventually grew at a faster rate and to a greater weight than the shoot. The relative growth rate and final yield of dry matter of the shoot were greatest at 24 °C and of the root between 17 and 24 °C. The relative rate of expansion and the final area of the leaf surface were also greatest at 24 °C, whilst the rates of production and of unfolding of leaves were greatest at about 17 °C. All these attributes were increased with increased radiation. Net assimilation rate increased almost proportionately with radiation and was not significantly affected by temperature.The relationships of total leaf area with plant dry weight, root dry weight with shoot dry weight, and total leaf number with plant dry weight were scarcely affected by changes in radiation, but were much influenced by temperature. Plants of the same dry weight generally had bigger roots and smaller areas of leaf surface as temperatures departed from 24 °C and had most leaves at 17 °C. Sugar concentrations in the storage root were greatest at 17 °C, but the total amount of sugar was about the same at 17 and 24 °C. The concentration of sugar in the storage root depended on root size.Thus, temperature affected both the rate and pattern of development, and radiation affected the rate but not the pattern of development.

Studies on maturation changes in fruits induced by ionizing radiation. II

Tomatoes (Licopersicon esculentum MILL. ) of three stages of maturity, mature green, breaker and light pink fruits were used in this experiment. Tomato fruits were irradiated with 60Co gamma rays at 0r, 5. 0×104r and 1. 0×106r at the rate of 2. 5×105r/hour. Temperatures during the irradiation and the storage were at about 20°C. The results obtained here were as follows:1. The pigmentation of tomatoes which were irradiated by gammarays at stages of breaker and light pink was delayed. The destruction of chlorophyll and the increasing of lycopene during ripening were apparently suppressed with higher doses. Gamma irradiation caused the considerable softening of the tissue immediately after irradiation. The subsequent change of softening in irradiated fruits was smaller than that in unirradiated ones. There was a decrease in protopectin in irradiated fruits immediately after irradiation. The titrative acidity and the amount of total sugar were not affected by gamma irradiation. The reduction of ascorbic acid by irradiation seemed to be greater in fruits of breaker stage than in those of light-pink.2. Carbon dioxide production of tomatoes irradiated at breaker stage increased with higher doses and this increased carbon dioxide production lowered to some extent at 24 hours after irradiation. These irradiated fruits exhibited the climacteric-like rise at the same period as that in unirradiated ones. Carbon dioxide production in tomatoes irradiated at light-pink stage was slightly greater than that in unirradiated ones, and light-pink fruits did not exhibited the climacteric like rise in both irradiated and unirradiated fruits.3. The effect of pyruvate and malate on carbon dioxide output in tissue slices increased in irradiated fruits more than in unirradiated ones. Gamma irradiation at 1.0×106r stimulated the ethylene formation. The increasing rate was higher in mature green fruits than in others. The rates of ethylene production decreased in all irradiated fruits 5 days after irradiation.4. The organoleptic evaluation showed the acceptability of the irradiated tomatoes lowered with the high dose.

THE EFFECT OF CHLORINE ON THE HYGROSCOPICITY OF FLUE-CURED TOBACCO

Chlorine from 20 to 50 pounds per acre had no effect on yield or leaf-grade quality of flue-cured tobacco grown on a Fox loamy sand. Increased applications of chlorine increased the chlorine content, moisture uptake, and decreased the rate of burn of the cured leaf but had no effect on the amount of total sugars.

EFFECTS OF CATIONS ON SUGAR ABSORPTION BY ISOLATED SURVIVING GUINEA PIG INTESTINE

The rate of absorption of glucose from isolated surviving guinea pig intestine increases with increase of the concentration of glucose in the lumen until a maximum rate is obtained. The relation between absorption rate of glucose and initial glucose concentration conforms to an equation of the Michaelis–Menten type. The apparent Km(half saturation concentration) is 7 × 10−3M. Increase of the concentration of potassium ions in the Ringer–bicarbonate solution bathing the intestine leads to an increase of the rate of glucose absorption, this being most marked with 15.6 meq./liter K+and 14 mM glucose. No such stimulating action of potassium ions is observed on glucose absorption under anaerobic conditions. The effect of increased potassium ion concentration is to accelerate the rate of transport found with low concentrations of glucose to the maximum value found with high concentrations of the sugar. Sodium ions must be present for glucose absorption to take place and omission of magnesium ions from a Ringer–bicarbonate solution, containing 15.6 meq./liter K+, brings about a decreased rate of active glucose transport. Magnesium ions are necessary for the stimulated rate of glucose absorption obtained in the presence of potassium ions. The presence of ammonium ions decreases the rate of glucose absorption. Potassium ions may be effectively replaced by rubidium ions for stimulation of glucose transport. Cesium ions do not activate. The proportion of glucose to fructose appearing in the serosal solution, when fructose is absorbed from the mucosal solution, depends on the concentration of fructose present. The proportion may be as high as 9:1 with low (7 mM) fructose concentrations; it decreases with increasing fructose concentrations. The active transport of fructose, as demonstrated by the conversion of fructose in the isolated surviving guinea pig intestine, is enhanced by the presence of potassium ions (15.6 meq./liter). The rate of transport of fructose itself is unaffected by potassium. Using radioactive glucose and fructose, it is shown that the total amount of sugar transferred through the intestine as estimated by the radioactivity appearing in the serosal solution is approximately that calculated from chemical analyses. Potassium ions have no activating action on the transport of sugars such as sorbose, mannose, and D-glucosamine, but have a marked effect on galactose transport. The results support the conclusion that potassium ions do not influence active transport of glucose, fructose, and galactose by a change of intestinal permeability to these sugars, but do so by affecting a specific phase involved in the mechanism of active transport of sugars. The presence of L-glutamine stimulates active transport of glucose, whereas that of L-glutamate tends to diminish it.

EFFECTS OF CATIONS ON SUGAR ABSORPTION BY ISOLATED SURVIVING GUINEA PIG INTESTINE

The rate of absorption of glucose from isolated surviving guinea pig intestine increases with increase of the concentration of glucose in the lumen until a maximum rate is obtained. The relation between absorption rate of glucose and initial glucose concentration conforms to an equation of the Michaelis–Menten type. The apparent Km(half saturation concentration) is 7 × 10−3M. Increase of the concentration of potassium ions in the Ringer–bicarbonate solution bathing the intestine leads to an increase of the rate of glucose absorption, this being most marked with 15.6 meq./liter K+and 14 mM glucose. No such stimulating action of potassium ions is observed on glucose absorption under anaerobic conditions. The effect of increased potassium ion concentration is to accelerate the rate of transport found with low concentrations of glucose to the maximum value found with high concentrations of the sugar. Sodium ions must be present for glucose absorption to take place and omission of magnesium ions from a Ringer–bicarbonate solution, containing 15.6 meq./liter K+, brings about a decreased rate of active glucose transport. Magnesium ions are necessary for the stimulated rate of glucose absorption obtained in the presence of potassium ions. The presence of ammonium ions decreases the rate of glucose absorption. Potassium ions may be effectively replaced by rubidium ions for stimulation of glucose transport. Cesium ions do not activate. The proportion of glucose to fructose appearing in the serosal solution, when fructose is absorbed from the mucosal solution, depends on the concentration of fructose present. The proportion may be as high as 9:1 with low (7 mM) fructose concentrations; it decreases with increasing fructose concentrations. The active transport of fructose, as demonstrated by the conversion of fructose in the isolated surviving guinea pig intestine, is enhanced by the presence of potassium ions (15.6 meq./liter). The rate of transport of fructose itself is unaffected by potassium. Using radioactive glucose and fructose, it is shown that the total amount of sugar transferred through the intestine as estimated by the radioactivity appearing in the serosal solution is approximately that calculated from chemical analyses. Potassium ions have no activating action on the transport of sugars such as sorbose, mannose, and D-glucosamine, but have a marked effect on galactose transport. The results support the conclusion that potassium ions do not influence active transport of glucose, fructose, and galactose by a change of intestinal permeability to these sugars, but do so by affecting a specific phase involved in the mechanism of active transport of sugars. The presence of L-glutamine stimulates active transport of glucose, whereas that of L-glutamate tends to diminish it.