J. Physiol. (1976), 263, pp. 101-114
`With 8 text-figures
`Printed in Great Britain
`
`101
`
`SUGARS AND SUGAR DERIVATIVES
`
`WHICH INHIBIT THE SHORT-CIRCUIT CURRENT OF THE
`EVERTED SMALL INTESTINE OF THE RAT
`
`By I. W. MUFLIH* anp W. F. WIDDAS
`
`From the Department of Physiology, Bedford College,
`Regent’s Park, London NW1 4NS
`
`(Received 29 December 1975)
`
`SUMMARY
`
`1. The short-circuit current of everted rat intestine supported on a
`perforated cannula proved to be stable for up to 3 hr and has been used
`to study competition between transportable and non-transportable sugars.
`2. 4,6-O-Ethylidene-x-D-glucopyranose (ethylidene glucose) and 4,6-O-
`benzylidene-«-p-glucopyranose
`(benzylidene glucose),
`two non-trans-
`portable inhibitors of the hexose transfer system in human erythrocytes,
`were foundto reduce the short-curcuit current generated by transportable
`sugars such as galactose or 3-O-methyl glucose.
`3. These compounds were also found to reduce the basal short-circuit
`current established by the everted intestine in a sugar-free Krebssolution.
`Both types of inhibition approached saturation at the higher concentra-
`tions used.
`4, Similar inhibitory properties were shown by mannose, a non-actively
`accumulated monosaccharide, and by the f-disaccharides lactose and
`cellobiose.
`5. It is suggested that this common pattern of behaviour is due to the
`ability of these compoundsto react with the sites for active hexose trans-
`fer but without translocation by the system. The significance of the in-
`hibition of the basal short-circuit current is briefly discussed in this
`context.
`
`INTRODUCTION
`
`Soon after the publication of the hypothesis by Crane (1960), Crane,
`Miller & Bihler (1961) regarding Na+ dependent sugar transport across the
`mucosal membraneof the intestine, it was considered, e.g. by Schultz &
`Zalusky (1963a, 6b)
`that the increments in the short-circuit current
`induced by the actively transported sugars were in support of this
`* Present address: Physiology Department, College of Medicine, Al-Mustansiriyah
`University, Baghdad, Iraq.
`
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`

`

`102
`
`I.W. MUFLIH AND W. F. WIDDAS
`
`hypothesis. During the last 15 years many studies have been made to
`determine the underlying processof active sugar accumulation on the basis
`of short-circuit current and potential difference measurementsusing in vitro
`preparations (e.g. Barry, Dickstein, Matthews & Smyth (1961), Barry,
`Smyth & Wright (1965), Clarkson, Cross & Tool (1961), Quay & Armstrong
`(1969) and Field, Fromm & McColl (1971) but the short-circuit current
`techniques had not so far been used to study competitive inhibition
`between sugars. Nevertheless a few reports have demonstrated that
`fructose (Asano, 1964; Lyon & Crane, 1966) and 2-deoxyglucose (Lyon &
`Crane, 1966) inhibited the basal electrical parameters recorded in sugar-
`free solutions. Barry, Eggenton & Smyth (1969) showed that mannose
`(28 mo) inhibited the basal transepithelial potential, an effect which they
`ascribed to osmotic gradients.
`showed that 4,6-O-ethylidene-a-p-gluco-
`Baker & Widdas
`(1973)
`pyranose (ethylidene glucose) could react strongly with the hexose trans-
`fer system in red cells and competitively inhibit glucose exit from thecell
`but could not enter red cells on the hexose system. Similar observations
`with a related compound, 4,6-O-benzylidene-e-p-glucopyranose (benzyl-
`idene glucose) have been reported on the hexose transfer system of the
`red cells by Novak & Lefevre (1974).
`In the present work, therefore, we set out to investigate the effects of
`knownnon-transportable competitive inhibitors of the hexose system in
`human red cells on the short-circuit current of everted rat intestine in-
`duced by the actively transported sugars. It was considered that if the
`compound, e.g. (ethylidene glucose, benzylidene glucose) could react with
`the intestinal hexose transport system without being transported by it,
`then it should inhibit competitively those increments in electrical para-
`meters which were dependent upon a small concentration of the actively
`transported sugars.
`In addition to ethylidene glucose (EG) and benzylidene glucose (BG),
`the effects of mannose and lactose on the short-circuit current generated
`bythe actively transported sugars were investigated. In a continuation of
`this study the effects of cellobiose and phloridzin on the basal short-
`circuit current recorded in sugar-free Krebs solution were examined.
`A preliminary account was presented to the Physiological Society
`(Muflih & Widdas, 1976).
`
`METHODS
`
`Male Albino rats of Wistar strain were used in this work. The rats were adult and
`usually in the weight range 350-450 g. They were maintained on a standard com-
`mercial diet, food and water being available ad libitum. Under Nembutal (pento-
`barbitone sodium) anaesthesia,
`the peritoneal cavity was opened by mid-line
`incision and the exposed viscera was rinsed continuously with Krebs saline solution
`
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`

`

`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT 103
`
`at laboratory temperature. Two openings were made through theintestinal wall,
`one at each end of the small intestine. The proximal opening was connected to a
`calibrated saline (Krebs) reservoir via a polyethylene tube. Intestinal contents
`were gently washed out by administering 25 ml. Krebssaline solution (at laboratory
`temperature) from the reservoir. A length of jejunum (8-10 cm long) was excised
`from the region in between 25-35 or 35-45 em from the end of the duodenum. The
`excised segment was then immersed in the Krebssaline solution and a length of
`thin glass rod was passed through the lumen. The intestine was ligatured near to
`the end of the segment which was rapidly everted and passed over a perforated
`
`Current
`
`Agar p.d.
`electrode
`electrode ~Qy JPsiagcl
`
`=paPolomsohonnenexhonyneespeoNOF
`i 17\/7E_]
`
`7r
`
`oe
`
`eeee
`
`\/
`
`/
`
`Fig. 1. A, supporting cannula for everted segmentof intestine. B, cannula
`and segment in electrode assembly in water-jacketed bath.
`
`supporting cannula made from a disposable needle container (Fig. 1). Lightly tied
`ligatures secured the segment above and below the perforations. The effective area
`of the mucosa between the two ligatures (without making any allowance for the
`macroscopic and microscopic infoldings of the mucosa) was 10 cm?. The time that
`elapsed between excision’ of the segment and the onset of incubation was less than
`3 min. The supporting cannula (with the gut) was mountedin an electrode assembly
`similar to that described by Barry et al. (1965). Current was supplied by a series of
`12 V dry batteries via a potentiometer which was driven by a low-inertia motor
`energized by an amplifier connected to the output of the potential measuring device
`(a Vibron Electrometer 33B) so as to form a simple feed-back servo which short-
`circuited the preparation. The current was monitored by a Kipp recording micro-
`graph BD2 (Kipp & Zonen).
`12
`
`PHY 263
`
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`

`

`104
`
`I.W. MUFLIH AND W. F. WIDDAS
`
`(1932) saline of composition (mm):
`Solutions were made in Krebs-Henseleit
`Na+ 144, K+ 5-9, Ca?+ 3-4, Mg?+ 1-2, Cl- 127-1, PO, 1:2, HCO; 25 and gassed with
`95% O,-5 % CO,. Sugars were Analar grade.
`Ethylidene glucose was purified by preparative paper chromatography before use.
`Benzylidene glucose was prepared for us by D. A. Basketter according to the
`method followed by Novak & Lefevre (1974).
`Sugar-free Krebs solution (5 ml.) was recirculated at the serosal side of the seg-
`ment throughout the experiment, glass dropping chambers in the tube lines provided
`air gaps to maintain theelectrical isolation of the serosal fluid.
`In the presence and absence of the actively transported sugars (galactose or
`3-O-methyl glucose), addition of different concentrations of the non-transportable
`sugars or phloridzin was in stepwise increments each for 6 min by which time the
`short-circuit current achieved a steady rate. In some experiments ethylidene glucose
`was present on the serosal side of the segment while actively transported sugar
`(3-O-methyl glucose) solution was on the mucosal side.
`
`200
`
`150
`
`100
`
`
`
`s.c.c.(uA)
`
`50 3 (40:5) mm
`
` 0
`
`50
`
`100
`
`150
`
`Time (min)
`
`Fig. 2. Short circuit (8.c.c.) from everted intestine showing the maintained
`response in the absence of sugar and in the presence of 3-O-methyl glucose
`at 3 and 10 mm. The points and lines are the means and s.£. of four
`experiments.
`
`RESULTS
`
`Control experiments
`The use of the supporting cannula for the everted sac of small intestine
`was found to make the responses of the tissue more reproducible and the
`short-circuit current was stable for from 2-3 hr.
`Fig. 2 summarizes the results of four experiments in which a basallevel
`of short-circuit current was followed for 40 min and then two increments
`of current induced by 3 and 10 mm 3-O0-methyl glucose respectively were
`followed, the whole experimentlasting 24 hr.
`
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`

`

`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT 105
`
`In the presence of metabolizable sugar such as glucose the preparation
`also showed good recovery properties from the depressive effects of
`anoxia, provided this only produced a partial depression of short-circuit
`current. Table 1 summarizes three experiments where a period of anoxia
`was given at 50 and 150 min from thestart of the experiment.
`Even after 150 min the restoration of oxygenation fully restored the
`short-circuit current induced by 4-4 mm glucose and there was no reason to
`fear that oxygenation of the tissue may have deteriorated over the course
`of an experiment in which full oxygenation was continuously maintained.
`
`TaBLE 1. The recovery characteristics of the intestinal short-circuit current in-
`duced by 4:4 mm glucose in a preparation subjected to periods of anoxia
`Thefirst and second anoxic periods were started at about 50 and 150 min respec-
`tively from setting up the segment. Means ands.£. of three experiments are given.
`Gas used to
`aerate the
`medium
`
`Experiment
`
`Duration
`(min)
`
`I,,
`(HA)
`
`1. Initial steady state
`2. First anoxic period
`Recovery
`3. Second anoxic period
`Recovery
`
`95% O.-5 % CO,
`95 % N.-5% CO,
`95% 0,-5 % CO,
`95% N,-5% CO,
`95% O,-5 % CO,
`
`15
`14-17
`10-15
`15
`10
`
`128+ 14
`64+ 12
`134+ 22
`67+12
`148+ 30
`
`Competitive experiments
`In the competitive experiments an increment in short-circuit current
`was first
`induced by a transportable sugar (galactose or 3-O-methyl
`glucose) at submaximal concentration; then stepwise additions of the in-
`hibitory sugar were madewhile keeping the concentration of the transport-
`able sugar constant throughout.
`Figs. 3A and 4A show the graded decrease in short-circuit current
`brought about by increasing concentrations of ethylidene glucose and
`benzylidene glucose respectively.
`The relationship in both cases is hyperbolic and similar except that
`benzylidene glucose is effective at lower concentrations than ethylidene
`glucose. In experiments in which 14-7 mm ethylidene glucose was placed
`on the serosal side of the segment, only a small statistically insignificant
`reduction in short-circuit current was observed.
`Figs. 5A and 6A show similar graded reductions in short-circuit
`current produced by mannose andlactose as the inhibitory sugars.
`
`Inhibition of basal short-circuit current
`In addition to producing graded reductions in the short-circuit current
`induced by a transportable sugar the same inhibitory sugars were found to
`12-2
`
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`
`

`

`5-5 mM galactose
`
`A
`
`15
`10
`.
`.
`[Ethylidene glucose] (mm )
`
`20
`
`I.W. MUFLIH AND W. F. WIDDAS
`
`106
`
`
`
`As.c:c.(WA)
`
`Basal
`
`—80
`
`
`
`Fig. 3. Effect of ethylidene glucose on the short-circuit current of everted
`rat intestine. (A), means of two experiments showing inhibition of I,,
`induced by 5-5 mm galactose. (B), means of two experiments inhibiting the
`basal short-circuit current. I,, = 0 represents the steady-state current
`after about 45 min in sugar-free Krebs solution.
`
`
`
`100 - 12mm_3-O-methyl-glucose
`
`80
`
`60
`
`
`
`$.€.¢.(uA)
`
` 2 3 4
`
`
`
`
`
`[Benzylidene glucose] (mm)
`
`
`
`Fig. 4. Effect of benzylidene glucose on the short-circuit current of everted
`rat intestine. Means of two experiments: (A) in competition with 12 mm
`3-O-methyl glucose, (B) showing inhibition ofthe basal short-circuit current.
`I,, = 0 represents the steady current after about 45 min in sugar-free
`Krebs solution.
`
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`

`

`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT 107
`
`100
`
`6-6 mM galactose
`
`15.20.
`{Mannose] (mm )
`
`«25
`
`«30
`
`+35
`
`< S
`
`u
`
`50
`
`0
`Basal 7
`5.¢.¢.
`
`= —50
`
`< vg
`
`v 4
`
`Fig. 5. Effect of mannose on the short-circuit current of everted rat intes-
`tine. Means of two experiments (A) in competition with 6-6 mm galactose,
`(B) showing inhibition of the basal short-circuit current. I,, = 0 repre-
`sents the steady current after about 45 min in sugar-free Krebs solution.
`
`—100 —150
`4-4 mM galactose : 60
`
`Zz
`
`= v¥
`
`Basal
`=
`$.c.c
`
`&y
`
`j 20uy
`<1
`
`40
`
`20
`
`0
`
`10
`actose]
`[L t
`
`1(
`
`15
`(mM
`Mm)
`
`Fig. 6. Effect of lactose on the short-circuit current of everted rat intestine.
`Means of two experiments (A) in competition with 4-4 mm galactose, (B)
`showing inhibition of the basal short-circuit current. J,, = 0 represents the
`steady current after about 45 min in sugar-free Krebs solution.
`
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`

`

`108
`
`I.W. MUFLIH AND W. F. WIDDAS
`
`produce a graded lowering of the basal short-circuit current when added
`to the mucosal bathing fluid in the absence of a transportable sugar. In all
`cases the preparation wasleft to equilibrate in sugar-free Krebs solution
`for at least 45 min and the short-circuit current had settled down to a
`steady state which was arbitrarily taken as the zero from which experi-
`mentally induced changes occurred.
`Figs. 3B, 4B, 5B and 6B show the reductions in basal short-circuit
`current produced by the same sugars.
`All curves are hyperbolic andif it is assumed that the change in short-
`circuit current is brought about by the occupancyofsites by the inhibitor
`sugar we may write
`
`Algo =k
`
`Cc
`C+Ky
`
`(1)
`
`where AJ,, is the change in short-circuit current, C is the concentration of
`inhibitory sugar, K, its half-saturation concentration and k a constant.
`This can be linearized as
`
`(2)
`C[Algy = 7 (C+K,)
`and a plot of C/AI,, vs. C should give a straight line. This is the equivalent
`of a Hanes (1932) plot and is recommended by Riggs (1972) as more suit-
`able for use when fitting a line to the experimental points by a least-
`squares analysis. The intercept on the abscissa is — Ky, the half-saturation
`concentration of the inhibitory sugar. The same plot can be used for the
`decrements in the short-circuit current in the competitive inhibition type
`of experiments but in this case the intercept would be— K,[I + (S/Ky)],
`where S is the concentration of transportable sugar and Ky,its half-
`saturation concentration. At the low concentrations of transportable sugars
`used, the term in brackets will be of the order 1-5, but estimates of the
`true K, can be made bydividing the intercept by [1+ (S/Ky)].
`In Fig. 7 the above plot has been applied to the data for benzylidene
`glucose both when inhibiting the basal short-circuit current and when
`inhibiting the short-circuit current induced by 3-O-methyl glucose. The
`results from this plot and similar plots for the other sugars yield rough
`values for the half-saturation constants which are collected in Table 2.
`The inhibitory effects of lactose are in contrast with the stimulatory
`effects seen with the disaccharides, maltose and sucrose. However, the
`intestine of adult rats is known to lack a f-disaccharidase (Alvarez & Sas,
`1961; Doell & Kretchmer, 1962) and the effects of another f-disaccharide,
`i.e. cellobiose were therefore examined. It was found that this sugar was
`similar to lactose in inhibiting the basal short-circuit current but showed
`less affinity having a higher half-saturation concentration (K; = 6-9 mm).
`
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`

`

`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT109
`
`Phloridzin, which classically inhibits the short-circuit current generated
`by actively transported sugar such as 3-O-methyl glucose (Schultz &
`Zalusky, 1964), was also found to inhibit the basal short-circuit current
`andresults of two experiments with this drug are shown in Fig. 8. Although
`not truly hyperbolic (there may have been non-specific uptake and de-
`pression of the effective bath concentrations at the lowest concentrations)
`
`[Benzylidene glucose] (mm)
`
`12 mm 3-O-methyl glucose
`
`-—50
`
`—100
`
`
`
`
`
`[B-G)/\s.c.c.(mA~')
` Basal s.c.c.
`
`—150
`
`Fig. 7. Linearized plot of results for benzylidene glucose experiment shown
`in Fig. 4. Lines were obtained by a least-squares regression analysis.
`Intercept on the abscissa gives the K, for inhibition of the basal J,, but
`not for the competitive experiment (see text).
`
`TasBie 2. Inhibitory constants (K,s) of non-transportable sugars or derivatives in
`competition with transportable sugars and when inhibiting the basal current. Data
`obtained from Hanes plots as in Fig. 7. For competition experiments K; = intercept
`(1+S/K,), where S is the concentration of transportable sugar and Ky,its half-
`saturation constant
`(for galactose K, = 12:5mm for 3-O-methyl glucose Ky =
`19-1 mm, Muflih, 1975)
`
`Basal
`Competitive inhibition
`
`sr———_—__—inhibition:
`Transported sugar
`K, (mm)
`Inhibitor
`K, (mm)
`
`Ethylidene glucose
`Benzylidene glucose
`Mannose
`Lactose
`Phloridzin
`
`Galactose (5-5 mM)
`3-O-methyl glucose (12 mm)
`Galactose (6-6 mm)
`Galactose (4-4 mm)
`—
`
`7:2
`1-0
`11
`3:8
`—
`
`6-7
`1-2
`10
`4-9
`39 x 10-3
`
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`

`

`110
`
`I, W. MUFLIH AND W. F. WIDDAS
`
`there is evidence of saturation at higher concentrations and the value of
`current maximally inhibited is of the same order as that with the non-
`transportable sugars.
`
`[Phloridzin] (um)
`40
`60
`
`80
`
`100
`
`20
`
`.
`
`Basal
`s.c.c.70
`
`.0
`
`—10
`
`—20
`<=> —30
`¥¥
`“ —40
`“1
`
`—50
`
`—60
`
`—70
`
`Fig. 8. Effect of phloridzin on the basal short-circuit current of everted rat
`intestine. Two experiments were carried out; J,, = 0 represents the basal
`steady current after about 45 min in a sugar-free medium.
`
`DISCUSSION
`
`The experiments described, in this study necessarily took a considerable
`time; not only was it necessary to allow 6 min for the short-circuit current
`to reach a steady state at each sugar concentration but to attain the basal
`level in sugar-free Krebs solution required an initial settling down period
`of from 45 min to 1 hr usually with at least one change of sugar-free
`medium.
`The everted gut supported by the perforated rigid cannula proved to be
`stable and to give consistent short-circuit current changes for up to 3 hr.
`The reason for the improved stability has not been investigated in detail
`but it was observed that muscular movements (seen in freely hanging
`preparations) were absent and the slight distension of the sac may have
`ensured more uniform oxygenation. The cannula also holds the sac so that
`its position relative to internal and external electrodes does not change
`during an experiment.
`Thus the preparation appeared to avoid oxygenation difficulties such
`as observed by Munk (1972) in everted rat intestine and the interference
`due to muscular contractions observed in everted segments of hamster
`intestine by Baker, Lo & Nunn (1974).
`
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`

`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT i111
`
`Apart from the studies of Quay & Armstrong (1969) with bull frog
`intestine and those ofField ef al. (1971) with strips ofrabbit ileum, previous
`investigators have usually failed to obtain comparable stability for a
`sufficient length of time to complete such experiments.
`In competitive experimentsit was possible to study the changesin short-
`circuit current produced by varying concentrations of non-transportable
`sugars (ethylideneg lucose, benzylidene glucose, mannose and_lactose)
`in the presence of constant concentrations of the actively trans-
`ported sugars (galactose or 3-O-methy] glucose). The non-transportable
`sugars all had inhibitory effects in that they produced decrements in the
`short-circuit current. Further, these decrements were graded with con-
`centration in a manner suggesting saturation at high concentration. The
`action was assumed to be a membrane one, wherebythe inhibitory sugar
`combined with sites on the active sugar transforming mechanism but in
`such a way that translocation was impossible. The increments in short-
`circuit current which accompanied the translocation of the actively trans-
`ported sugar (which was displaced) were therefore progressively reduced.
`That the action was at the outer membrane was suggested by the fact
`that onset of the inhibitory effect developed without delay when the sugar
`was in the mucosal fluid. Ethylidene glucose on the serosal surface had no
`significant inhibitory effect. Lactose was unlikely to penetrate by diffusion
`through intact mucosa and, if it had been hydrolysed, both the sugars
`formed as products of hydrolysis would have stimulated the short-circuit
`current. However, the absence of a £-glycosidase enzyme (necessary for
`lactose hydrolysis) from the adult rat intestine reported by Alvarez & Sas
`(1961) has been fully confirmed by Doell & Kretchmer (1962), Koldovsky
`& Chytil (1965), and Semenza (1968). Thus the effect of lactose was most
`likely to be exerted extracellularly and this supports the view that thesite
`of action was the outer membraneof the absorptive surface in the micro-
`villi of the mucosalcells.
`Lactose andcellobiose, the two £-glycosides used, were both inhibitory
`whereas maltose and sucrose produced increases in short-circuit current
`(Muflih, 1975).
`An interesting observation of the present study was the inhibitory
`effects of these non-transportable sugars on the short-circuit current
`recorded across the intestine in Krebs solution which was free of trans-
`portable sugar. In these experiments as in the competitive ones, the decre-
`ments obtained in the short-circuit current by the addition of any one of
`the non-transportable sugars were concentration dependent in a manner
`suggesting a saturable effect. The K,s obtained for inhibiting the basal
`short-circuit current were similar to those obtained in inhibiting the short-
`circuit current generated by the transported sugars. This finding may
`
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`

`112
`
`I.W. MUFLIH AND W. F. WIDDAS
`
`suggest that reactions were occurring either at the samesites or at sites
`with similar affinities. However, there may be a difference between those
`sugars like mannose which lack the stereo-specificity at carbon atom 2
`and the other non-transportable sugars, ethylidene glucose, benzylidene
`glucose, lactose and cellobiose which have bulky groups at the opposite
`end of the glucose molecule. Indeed phloridzin may belong to this group
`since Newey, Sanford, Smyth & Williams (1963) have suggested that the
`hexosyl unit of the phloridzin plays an important part in the binding of
`this inhibitor.
`In summary, competition for a sugar binding site but without transloca-
`tion is probably the commonfeature relating to these non-transportable
`sugars in their reactions with the intestinal mucosa. The corollary to
`this view would be the hypothesis that at least part of the in vitro basal
`short-circuit current of the everted gut bathed in sugar-free medium was
`actually being carried (presumably without sugar) on the sugar trans-
`porting system. This would not be inconsistent with the hypothesis of a
`sodium-linked sugar carrier in accordance with Bihler (1965), Crane,
`Forstner & Eichholz (1965), Lyon & Crane (1966) and Goldner, Schultz &
`Curran (1969) but may not exclude someother form of coupling.
`The absence of the actively transported sugar in the medium does not
`exclude the possibility of a small leakage of intracellular sugar into the
`microvillal crypts and reabsorption with Nat on the transporting system,
`but this explanation would appear to be unlikely. Nevertheless the basal
`short-circuit current’s relation to the sugar transporting system may be
`peculiar to the in vitro preparation.
`It was observed that the further depression of the basal short-circuit
`current was greatest with saturating concentrations of mannose, inter-
`mediate with ethylidene glucose and smallest with benzylidene glucose
`and lactose. The reasons for this were not clear but may reflect different
`accessibility of the transport sites sinee the sizes of the sugars would fall
`in a similar order. Barry et al. (1969) considered that osmotic effects were
`involved in the depression of the potential difference by mannose (at 28
`mM) andthe inhibitions by this sugar only saturate at such levels of con-
`centration. However, osmotic effects can only play a minorpart since the
`inhibitions by benzylidene glucose and phloridzin are produced by osmoti-
`cally insignificant concentrations.
`
`During this work I.W.M. was supported by grants from the Calouste Gulbenkian
`Foundation and the University of Baghdad whichare gratefully acknowledged. We
`are grateful to Mr D. A. Basketter, B.Se., for the synthesis of benzylidene glucose
`and for purifying the ethylidene glucose.
`
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`SUGAR INHIBITORS OF SHORT-CIRCUIT CURRENT 113
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