Kinetics of Mucosal Influx of Glycylsarcosine, Glycine and Leucine into Hamster Jejunum and Ileum in Vitro

1979 ◽  
Vol 56 (1) ◽  
pp. 25-31 ◽  
Author(s):  
H. P. Schedl ◽  
D. Burston ◽  
E. Taylor ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Substrate Concentration ◽  
Experimental Conditions ◽  
Simple Diffusion ◽  
Distal Small Intestine ◽  
Diffusion Component ◽  
Wet Weight ◽  
Kinetics Of

1. This paper describes an investigation of the kinetics of influx of the dipeptide glycylsarcosine and the amino acids glycine and l-leucine into rings of everted hamster small intestine in vitro, in proximal and distal small intestine (jejunum and ileum). Results were expressed per unit wet weight of intestine. 2. At all concentrations studied (0·1–100 mmol/l), influx of glycylsarcosine was more rapid in the jejunum than in the ileum. In contrast, at all concentrations studied, influx of glycine and leucine was more rapid in the ileum than the jejunum. 3. Estimates of the simple diffusion component in total influx were made. This component became increasingly large as the substrate concentration was raised. After correction for simple diffusion, transport of all three substrates conformed to Michaelis-Menten kinetics in both jejunum and ileum. Values for simple diffusion, apparent Kt and Vmax. are reported. 4. Possibly physiological implications of the results are discussed, and it is pointed out that under experimental conditions similar to our own, simple diffusion is too large a component in total influx to be ignored.

scholarly journals Identification in skeletal muscle of a distinct extracellular pool of amino acids, and its role in protein synthesis

1971 ◽  
Vol 121 (5) ◽  
pp. 817-827 ◽  
Author(s):  
R. C. Hider ◽  
E. B. Fern ◽  
D. R. London
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Longus Muscle ◽  
Kinetics Of

1. The kinetics of radioactive labelling of extra- and intra-cellular amino acid pools and protein of the extensor digitorum longus muscle were studied after incubations with radioactive amino acids in vitro. 2. The results indicated that an extracellular pool could be defined, the contents of which were different from those of the incubation medium. 3. It was concluded that amino acids from the extracellular pool, as defined in this study, were incorporated directly into protein.

Absorption of beta-casomorphins from autoperfused lamb and piglet small intestine

1990 ◽  
Vol 259 (3) ◽  
pp. G443-G452 ◽  
Author(s):  
L. C. Read ◽  
A. P. Lord ◽  
V. Brantl ◽  
G. Koch
Keyword(s):  
Small Intestine ◽  
Intestinal Lumen ◽  
Physiological Conditions ◽  
Naturally Occurring ◽  
Gut Epithelium ◽  
Measured Absorption ◽  
Beta Casein ◽  
Kinetics Of

beta-Casomorphins (beta-CMs) derived from milk beta-casein may exert various opiate activities in milk-fed infants. To assess the physiological significance of beta-CMs as a source of circulating opioids in infants, we measured absorption rates of several beta-CMs under near-physiological conditions using in situ autoperfused lamb intestine. The naturally occurring beta-CMs, beta-CM-7 and beta-CM-4-amide, were absorbed readily into blood with no transfer into lymph. Uptake peaked within several minutes of the luminal infusion of peptide but then declined sharply and stopped within a further 10-15 min. The recovery in blood, intestinal contents, and tissue at the end of the 30-min experiment was less than 1% of the infused dose. The low recovery was due to rapid proteolysis based on in vitro studies that demonstrated half-lives of less than 5 min in lamb blood, luminal contents, and lymph. The synthetic dipeptidyl peptidase IV-resistant analogue beta-[D-Ala2]CM- 4-amide was stable during incubation in blood, lymph, or luminal contents and was absorbed into blood at rates that were maximal within several minutes and remained steady for the 30-min period. We conclude that although natural beta-CMs are transferred across the lamb small intestine, rapid degradation within the intestinal lumen, gut epithelium, and blood would prevent entry into the circulation under normal conditions. Val-beta-CM-7, a putative stable precursor, had similar stability and kinetics of absorption to beta-CM-7, results that exclude Val-beta-CM-7 as a stable precursor for delivery of beta-CMs to the circulation. Essentially identical results to those in lambs were obtained in 7-day-old piglets.

In vivo and in vitro Absorption of Amino Acids and Dipeptides in the Small Intestine of Uremic Rats

Nephron ◽  
1982 ◽  
Vol 31 (3) ◽  
pp. 273-276 ◽  
Author(s):  
G. Sterner ◽  
T. Lindberg ◽  
T. Denneberg
Keyword(s):  
Amino Acids ◽  
Small Intestine

Transport of amino acids by isolated gills of the mussel Mytilus californianus Conrad

1975 ◽  
Vol 62 (2) ◽  
pp. 313-325
Author(s):  
S. H. Wright ◽  
T. L. Johnson ◽  
J. H. Crowe
Keyword(s):  
Amino Acids ◽  
Significant Role ◽  
Transport Mechanism ◽  
Surrounding Medium ◽  
Gill Tissue ◽  
Mytilus Californianus ◽  
Animal Nutrition ◽  
Neutral Amino Acids ◽  
Kinetics Of

The unidirectional influx of cycloleucine into in vitro preparations of gill tissue of the mussel, Mytilus californianus, was determined. Influx was found to be linear for at least an hour, and the kinetics of cycloleucine influx conformed to Michaelis-Menten type kinetics. The transport mechanism(s) for cycloleucine is relatively specific for the L-enantiomorph of neutral amino acids, and is capable of accumulating cycloleucine to intracellular concentrations much higher than those of the surrounding medium. Evedence is presented that the transport of amino acids by gill tissue plays a significant role in whole animal nutrition.

In Vitro Absorption of Amino Acids by the Small Intestine of Sheep

1976 ◽  
Vol 42 (1) ◽  
pp. 201-207 ◽  
Author(s):  
W. A. Phillips ◽  
K. E. Webb ◽  
J. P. Fontenot
Keyword(s):  
Amino Acids ◽  
Small Intestine

scholarly journals Nutritional availability of amino acids from protein cross-linked to protect against degradation in the rumen

1984 ◽  
Vol 52 (2) ◽  
pp. 239-247 ◽  
Author(s):  
John R. Ashes ◽  
Jim L. Mangan ◽  
Gurcharn S. Sidhu
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Medicago Sativa ◽  
Terminal Ileum ◽  
Milk Protein ◽  
The Other ◽  
Molar Basis ◽  
Lactating Goats ◽  
Total Milk

1. Casein was labelled with pairs of radioactive amino acids, lysine, tyrosine and leucine, one with I4C and the other with 3H, by jugular infusion into lactating goats followed by isolation of the double-labelled casein from the milk. Total milk protein was similarly labelled by jugular infusion of [35S]cystine. U-14C-labelled fraction- 1 leaf protein was isolated from lucerne (Medicago sativa) grown in an atmosphere of 14C022. The proteins were treated withdifferent levels(333 and667 mmol/kgprotein) offormaldehyde, glutaraldehyde and glyoxal.3. Absorption from the small intestine was measured in sheep with fistulas in the abomasum and terminal ileum, using Cr-EDTA as the digesta flow marker, by introducing radioactive casein into the abomasum.4. Lysine, tyrosine and cystine became increasingly unavailable for absorption from the small intestine of sheep with increasing levels of aldehyde. At the lower level (333 mmol/kg) the proportions of the amino acids that were unavailable were 0.192, 0.051 and 0.123 respectively. At the higher level of formaldehyde (667 mmol/kg) the corresponding values were 0.335, 0.201 and 0.432 respectively. Leucine was not made unavailable with formaldehyde.5. The proportions of lysine, tyrosine and leucine that were unavailable were higher, on a molar basis, after treatment of the proteins with the dialdehydes glutaraldehyde and glyoxal than after treatment with formaldehyde. However, the extent of protein protection provided by the dialdehydes in the rumen, measured using an in vitro procedure, was lower.

Urinary excretion of prostacyclin in a rat model of uteroplacental vasculature occlusion: implications for fetal growth retardation

1996 ◽  
Vol 8 (5) ◽  
pp. 895 ◽  
Author(s):  
M Hophy ◽  
S Harel ◽  
E Yavin
Keyword(s):  
Blood Flow ◽  
Urinary Concentration ◽  
Fetal Blood ◽  
Experimental Conditions ◽  
Pregnant Rat ◽  
Flow Interruption ◽  
Lower Ability ◽  
Wet Weight ◽  
High Concentrations

An experimental model was devised in the pregnant rat to study by a combined high pressure liquid chromatography and radioimmunoassay technique the accumulation of prostanoids (PNs) in the urine after transient-complete or permanent-partial interruption of the maternal-fetal blood flow. After 8 min of complete restriction of the blood flow in the pregnant rat at 18 days of gestation, the urinary concentration of 6-keto-prostaglandin F1 alpha (6k-PGF1 alpha, the stable prostacyclin metabolite) increased from 4.97 +/- 1.27 ng mg-1 creatinine to 8.09 +/- 2.47 ng mg-1 creatinine and 13.02 +/- 4.5 ng mg-1 creatinine after the second and third post-operative day respectively. The urinary concentration of the 2,3-dinor derivative of prostacyclin reached 12.35 +/- 5.44 ng mg-1 creatinine after the second post-operative day and was reduced to 4.71 +/- 1.94 ng mg-1 creatinine after the third post-operative day. The concentration of thromboxane B2 (TxB2, the stable thromboxane A2 metabolite) increased approximately 7-fold and 13-fold over that of the control after the second and third post-operative day respectively. The urinary concentration of the 2,3-dinor derivative of TxB2 (d-TxB2) increased from about 1.42 +/- 0.3 ng mg-1 creatinine to 4.49 +/- 0.9 ng mg-1 creatinine and 7.76 +/- 2.63 ng mg-1 creatinine under the same experimental conditions. Increases in the urinary concentrations of 6k-PGF1 alpha and d-TxB2 to 94 +/- 27.76 ng mg-1 creatinine and 12.05 +/- 2.26 ng mg-1 creatinine, respectively, were observed on the second post-operative day, after the restriction time was increased to 30 min. Permanent-partial occlusion of the maternal fetal circulation resulted in excretion of PNs in the urine to similar levels produced after transient-complete restriction. High concentrations of prostacyclin (range, 0.8 ng min-1 mg-1 wet weight) were produced in vitro by uterine preparations from restricted animals after the second post-operative day. Placenta preparations from restricted animals generally exhibited a lower ability to synthesize PNS (up to 0.006 ng min-1 mg-1 wet weight) compared with uterine tissue but produced more thromboxane than their sham counterparts. The data suggest that the uterus constitutes the main source for urinary PN excretion following short episodes of maternal-fetal blood flow interruption.

Intestinal calcium transport in the spontaneously hypertensive rat: response to calcium depletion

1986 ◽  
Vol 250 (4) ◽  
pp. G412-G419
Author(s):  
H. P. Schedl ◽  
D. L. Miller ◽  
R. L. Horst ◽  
H. D. Wilson ◽  
K. Natarajan ◽  
...  
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Calcium Transport ◽  
Spontaneously Hypertensive Rat ◽  
Calcium Depletion ◽  
Spontaneously Hypertensive ◽  
Distal Small Intestine ◽  
Wistar Kyoto

We previously found intestinal Ca2+ transport to be lower in the spontaneously hypertensive (SH) as compared with the Wistar-Kyoto control (WKY) rat. These animals were fed a relatively high (1%) Ca2+ diet, and the concentration of 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3] in serum was the same in both groups. In the present experiment we tested the possibility that the lower Ca2+ transport in the SH rat was the result of unresponsiveness to 1 alpha,25(OH)2D3. We fed diets high and low in Ca2+ and measured serum 1 alpha,25(OH)2D3 and Ca2+ transport. Serum 1 alpha,25(OH)2D3 increased in response to Ca2+ depletion at both 5 and 12 wk in both the WKY and SH rat. With high-Ca2+ diet, Ca2+ transport was lower in SH than in WKY when studied 1) in vitro in duodenum at 5 wk of age, and 2) in vivo in proximal and distal small intestine at 12 wk of age. Ca2+ transport increased in SH in response to Ca2+ depletion, but not in WKY, except in distal small intestine in vivo at 12 wk. In summary, although Ca2+ transport is lower in the SH as compared with the WKY rat when vitamin D activity is basal through feeding a high-Ca2+ diet, Ca2+ transport increases in the SH rat in response to the increase in 1 alpha,25(OH)2D3 produced by feeding a low-Ca2+ diet. We conclude that 1) the vitamin D-regulated component of mediated Ca2+ transport is intact in the SH rat and is unrelated to hypertension, and 2) mediated Ca2+ transport under basal conditions, i.e., nonvitamin D-regulated, differs in the SH and WKY rats and may be related to hypertension.

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