Electrical potentials associated with intestinal sugar transfer

1. The serosal transfer of the following eight amino acids: threonine, alanine, serine, histidine, valine, methionine, phenylalanine and leucine, was measured using everted sacs of anterior intestine taken from goldfish acclimatized to 8° C and incubated at 25° C. 2. All eight amino acids were actively transported and the serosal transfer correlated with the steady potential (P < 0·001) and with the amino acid‐evoked potential (P < 0·05) measured on the same preparations. 3. The goldfish rectum actively transported alanine and the steady potential was raised when alanine bathed the mucosa of the everted preparation. 4. L‐aspartic acid was partly transaminated to alanine by the goldfish anterior intestine; the rectum transaminated alanine to an unidentified amino acid which might have been serine, asparagine or glutamine or some mixture of these three. 5. It is suggested that L‐amino acids increase the ease by which sodium enters the mucosal cell but that it is the rate at which this sodium is transported across the basal membrane which determines the net serosal transfer of amino acids.

Section: Discussionmentioning

confidence: 99%

Amino acid transport in the goldfish intestine

Mepham¹,

Smith²

1966

“…The above evidence suggests that the transmural voltage across the anterior chiton intestine is metabolically dependent and is not directly affected by actively transported sugars as is vertebrate intestine (Barry et al 1964(Barry et al , 1969. The metabolically dependent transmural voltage across the anterior chiton intestine may be analogous to the metabolically dependent non-electrogenic pump suggested by Barry et al (1969), for vertebrate intestine.…”

Section: Discussionmentioning

confidence: 80%

The effect of carbohydrates on the intestinal potentials of Cryptochiton stelleri

Lawrence¹,

Mailman²,

Puddy³

1972

SUlMMARY1. The effect of various monosaccharides on the potential difference across the intestine of the invertebrate, Cryptochiton stelleri, was studied using an everted sac technique.2. D-Glucose, when present in the mucosal solution, increased the transmural potential across the anterior intestine but had no effect on electrical potentials across the posterior intestine.3. D-Galactose, when present in the mucosal solution, increased the transmural potential across the posterior intestine but had no effect on electrical potentials across the anterior intestine.4. D-Fructose and D-mannose, metabolizable but non-transported sugars, increased anterior intestinal potentials but not posterior intestinal potentials.5. 3-0-methylglucose, an actively transported (across the anterior intestine) but non-metabolizable sugar, did not alter potentials across either the anterior or posterior intestine.6. The addition of D-glucose to the serosal solution increased anterior intestinal potentials, but the serosal addition of D-galactose did not affect posterior intestinal potentials.7. NaF, phlorizin and anoxia prevented the increase in potential across the anterior intestine and phlorizin (104 but not 10-6 M) and NaF but not anoxia prevented the increase in potential across the posterior intestine.8. It was suggested that the effect of glucose on anterior intestinal potentials was a metabolic effect, whereas the effect of galactose on posterior intestinal potentials was related to the active transport of that sugar from mucosa to serosa.

“…), the short-circuit current (IrS) and the rate of active Na transport from the mucosa to the serosa (Barry, Dikstein, Matthews, Smyth & Wright, 1964;Schultz & Zalusky, 1964). In contrast, the p.d.…”

Section: Introductionmentioning

confidence: 96%

Effect of glucose and hyperosmolality on the electrical characteristics of dog colon mucosa in vivo.

Gazitúa¹

1981

SUMMARY1. A method has been developed to maintain the electrical characteristics of dog colon mucosa stable over prolonged periods in vivo. This was achieved by paying special attention to the constancy of the volume of the organ and its intraluminal pressure during perfusion.2. Intraluminal glucose elicits an increase in transmural potential and short-circuit current; this has been attributed to the presence of a Na-glucose co-transport process in this tissue.3. Na replacement by K in the perfusate caused an increase in the transmural potential, whereas mannitol substitution evoked an inversion. These observations are probably the result of diffusion potentials. In the mannitol solution, glucose effectively abolished the negative transmural potential, whereas in the K solution, the effect of the sugar was smaller than in the control.4. Perfusion of a hyperosmotic solution containing mannitol resulted in the development of streaming potentials across the mucosa. Their magnitude was reduced by addition of 2,4-dinitrophenol or by removal of Na from the perfusate. They were counteracted by replacement of mannitol by glucose. The streaming potentials showed no sign of saturability, reflecting a pronounced hydraulic conductivity of the epithelium.5. The rapidity of onset of the potential response to glucose was enhanced by increasing the perfusion rate, but the response to hyperosmolality was unaffected.6. Streaming potentials, diffusion potentials and glucose-evoked potentials are generally considered to be features of the small intestinal mucosa; their existence in the dog colon indicates that this epithelium has more in common with small gut than with the majority of mammalian colons.