Intestinal tissue PO2 and microvascular responses during glucose exposure

1980 ◽  
Vol 238 (2) ◽  
pp. H164-H171 ◽  
Author(s):  
H. G. Bohlen
Keyword(s):  
Blood Flow ◽  
Small Intestine ◽  
Normal Distribution ◽  
Vascular Resistance ◽  
Intestinal Blood Flow ◽  
Rat Small Intestine ◽  
Intestinal Tissue ◽  
Tissue Po2 ◽  
In Series ◽  
Glucose Exposure

The microvessels responsible for the major decrease in intestinal vascular resistance during the presence of glucose were defined. In addition, the normal distribution of tissue PO2 in the various layers of the intestinal tissue was measured at rest and during glucose exposure to determine if part of the absorptive hyperemia mechanism is related to a decrease in tissue PO2. In the rat small intestine, exposure of the mucosa only to glucose concentrations of 25--500 mg/100 causes a 20--25% dilation of all submucosal vessels in series with the mucosal vessels and mucosal arterioles. Total intestinal blood flow increased to 200-210% of control at all glucose concentrations. The tissue and perivascular PO2 in the villus apex decreased from 14.8 +/- 1.2 (SE) mmHg at rest to 6--8 mmHg during glucose exposure; the PO2 in the muscle and submucosal layers tended to slightly increase above a normal of 26.4 +/- 1.6 mmHg during glucose exposure. The data indicate virtually all intestinal arterioles are equally involved in absorptive hyperemia. The dilation of mucosal vessels may be related to a decrease in tissue PO2, but submucosal vessels dilate even though PO2 is slightly increased.

Nitric oxide modulates regional blood flow differences in the fetal gastrointestinal tract

1996 ◽  
Vol 271 (4) ◽  
pp. G598-G604 ◽  
Author(s):  
W. Q. Fan ◽  
J. J. Smolich ◽  
J. Wild ◽  
V. Y. Yu ◽  
A. M. Walker
Keyword(s):  
Nitric Oxide ◽  
Heart Rate ◽  
Blood Flow ◽  
Small Intestine ◽  
Vascular Resistance ◽  
Oxygen Delivery ◽  
Intestinal Blood Flow ◽  
Flow Reduction ◽  
Blood Flows ◽  
Blood Flow Reduction

We studied the role of endogenous nitric oxide (NO) in the regulation of gastrointestinal (GI) circulation in 11 chronically instrumented and unanesthetized late-gestation fetal sheep. Systemic and GI blood flows were measured by the radiolabeled microsphere technique. Mean arterial pressure (MAP), heart rate, blood flows, oxygen delivery, and vascular resistance were determined before and after infusion of the specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), to cumulative doses of 10 and 25 mg/kg. At both L-NNA doses, MAP increased, and combined ventricular output and heart rate decreased. GI blood flow and oxygen delivery decreased and vascular resistance increased for the stomach, all segments of the small intestine, and proximal colon and cecum but were unchanged in the middle and distal colon and rectum. Because blood flow reduction in the small intestine was pronounced (from 176 to 107 ml.min-1.100 g-1, P < 0.001) and blood flow in the large intestine was unchanged, distribution of intestinal blood flow became more uniform. Overall, blood flow reduction was proportionally greater in GI circulation than in the remainder of fetal circulation. In three additional animals we established that L-NNA reduced blood flow to the mucosal-submucosal layer (P < 0.02) but not to the muscularis serosa of the small intestine. In the same animals, L-arginine (250 mg/kg) restored systemic hemodynamics and partially restored small intestinal blood flow. Our results suggest that NO is an important differential regulator of vascular tone in the developing GI circulation.

Measurement of Blood Flow in the Main Arteriole of the Villi in Rat Small Intestine with FITC-Labeled Erythrocytes

1998 ◽  
Vol 56 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Joachim Ruh ◽  
Eduard Ryschich ◽  
Andreas Secchi ◽  
Martha Maria Gebhard ◽  
Florian Glaser ◽  
...  
Keyword(s):  
Blood Flow ◽  
Small Intestine ◽  
Rat Small Intestine

Differences in uptake and esterification of saturated analogues of cholesterol by rat small intestine

1986 ◽  
Vol 251 (4) ◽  
pp. G495-G500 ◽  
Author(s):  
A. K. Bhattacharyya
Keyword(s):  
Small Intestine ◽  
Intestinal Mucosa ◽  
Cholesterol Content ◽  
Cell Uptake ◽  
Cholesterol Concentration ◽  
Mucosal Cell ◽  
Rat Small Intestine ◽  
Intestinal Tissue

Coprostanol and cholestanol are two saturated analogues of cholesterol. The former, which is the A/B ring isomer of cholesterol, is a nonabsorbable sterol, whereas the latter, which has an A/B ring configuration closer to that of cholesterol, is absorbed only half as efficiently as cholesterol. Intestinal mucosal cell uptake and esterification, two important steps in absorption, were studied in vivo after feeding the sterols and in vitro using everted sacs of rat small intestine. The results showed that the intestinal tissue content of coprostanol, total and esterified, were significantly lower than that of cholestanol. Total cholesterol concentration in the intestinal tissue was similar throughout but the esterified cholesterol content increased significantly throughout the length of the intestine compared with controls. The study suggests that cholestanol is absorbable because its uptake and esterification are not limited, whereas coprostanol is nonabsorbable because its uptake and esterification are limited in the intestinal mucosa. Also, the two sterols stimulate the activities of cholesterol esterase, one of the cholesterol esterifying enzymes, in the intestinal mucosa. The present study along with previous studies suggests that the structure of the sterol molecule as a whole appears to be the important determinant for its uptake and esterification, and probably absorption, in the small intestine.

Decreases in splanchnic vascular resistance contribute to hypotensive effects of l-serine in hypertensive rats

2010 ◽  
Vol 298 (6) ◽  
pp. H1789-H1796 ◽  
Author(s):  
Ramesh C. Mishra ◽  
Saswati Tripathy ◽  
Jugal D. Gandhi ◽  
John Balsevich ◽  
Jawed Akhtar ◽  
...  
Keyword(s):  
Blood Flow ◽  
Small Intestine ◽  
Potassium Channel ◽  
Vascular Resistance ◽  
Oral Treatment ◽  
Peripheral Resistance ◽  
Hypertensive Rats ◽  
Blood Pressure Lowering Effect ◽  
Wky Rats ◽  
Calcium Activated Potassium Channel

l-Serine administration reduces mean arterial pressure (MAP) in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats rendered hypertensive by chronic oral treatment with the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester (l-NAME). To determine if the fall in MAP was due to decreases in vascular resistance or cardiac output (CO), and to record regional hemodynamic effects, we measured the distribution of fluorescent microspheres to single bolus intravenous injections of l-serine (1 mmol/kg) in 14-wk-old male WKY, SHR, and l-NAME-treated WKY rats. MAP and total peripheral resistance (TPR) were significantly higher ( P < 0.01), whereas CO was lower in l-NAME-treated WKY ( P < 0.01) and SHR ( P < 0.05). l-Serine administration led to a rapid fall in MAP (WKY 22%, l-NAME-WKY 46%, SHR 34%,) and TPR (WKY 24%, l-NAME-WKY 68%, SHR 53%), whereas CO was elevated. In WKY rats, l-serine induced an increase in blood flow only in the small intestine (53%) while it was more profound in several vascular beds of hypertensive rats [l-NAME-WKY: small intestine (238%), spleen (184%), diaphragm (85%), and liver (65%); SHR: small intestine (217%), spleen (202%), diaphragm (116%), large intestine (105%), pancreas (96%), and liver (93%)]. Pretreatment with a combination of apamin (a small calcium-activated potassium channel inhibitor) and charybdotoxin (an intermediate calcium-activated potassium channel inhibitor) abolished the l-serine-induced changes in blood flow and TPR. l-Serine acts predominantly on apamin- and charybdotoxin-sensitive potassium channels in the splanchnic circulation to increase blood flow, thereby contributing to the fall in TPR and the pronounced blood pressure-lowering effect of l-serine in hypertensive rats.

scholarly journals Specificity studies on enteropeptidase substrates related to the N-terminus of trypsinogen

1987 ◽  
Vol 241 (3) ◽  
pp. 721-727 ◽  
Author(s):  
P Jenö ◽  
J R Green ◽  
M J Lentze
Keyword(s):  
Small Intestine ◽  
Methyl Ester ◽  
Rat Small Intestine ◽  
Concerted Action ◽  
Intestinal Tissue ◽  
Alternative Substrates ◽  
Synthetic Substrate ◽  
Highly Active ◽  
N Terminus ◽  
Aminopeptidase A

The specificity of the synthetic substrate Gly-[L-Asp]4-L-Lys 2-naphthylamide originally developed for the assay of enteropeptidase (EC 3.4.21.9), was investigated with partially purified aminopeptidase. Our results indicate that, not only enteropeptidase, but also the concerted action of the aminopeptidases of the rat small intestine, can rapidly release 2-naphthylamine from the substrate. A previously undescribed, highly active, dipeptidylaminopeptidase, which hydrolyses a Gly-Asp dipeptide from the N-terminus of the substrate, was detected in rat small intestine. The resulting [L-Asp]3-L-Lys 2-naphthylamide fragment is then degraded by a combination of aminopeptidase A and N to yield free 2-naphthylamine. Thus the present substrate cannot be regarded as being specific for enteropeptidase, and its use leads to an over-estimation of enteropeptidase activity in homogenates and extracts of intestinal tissue. In order to prevent this non-specific hydrolysis by aminopeptidases, stereoisomeric substrates with the sequence L-Ala-D-Asp-[L-Asp]3-L-Lys methyl ester, D-Ala-[L-Asp]4-L-Lys methyl ester and L-Ala-[Asp]4-L-Lys methyl ester were synthesized and tested as alternative substrates by their ability to inhibit the enteropeptidase-catalysed activation of trypsinogen.

scholarly journals EFFECTS OF LENGTH AND REGION OF SMALL INTESTINAL GLUCOSE EXPOSURE ON BLOOD PRESSURE, SUPERIOR MESENTERIC ARTERY BLOOD FLOW AND PLASMA NORADRENALINE IN HEALTHY OLDER PARTICIPANTS

2018 ◽  
pp. 1-7
Author(s):  
R.S. Rigda ◽  
L.G. Trahair ◽  
T. Wu ◽  
T.J. Little ◽  
K. Lange ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Small Intestine ◽  
Superior Mesenteric Artery ◽  
Mesenteric Artery ◽  
Plasma Noradrenaline ◽  
Glucose Exposure ◽  
Small Intestinal ◽  
Mesenteric Artery Blood Flow ◽  
Occluding Balloon

Background: A substantial postprandial reduction in blood pressure (BP), triggered by the interaction of nutrients with the small intestine and associated with increases in heart rate (HR) and splanchnic blood flow, occurs frequently in healthy older people. Objective: The aim of this study was to determine whether these responses are influenced by the length and/or region of small intestine exposed to nutrients. Design: Randomized, single blind study. Setting: Clinical research laboratory. Participants: Ten healthy older participants (9M, 1F; age 65 – 79 yr). Intervention: On 3 separate study days, participants were intubated with a small intestinal catheter incorporating two duodenal infusion ports and an aspiration port, as well as an occluding balloon, which was positioned ~ 60 cm beyond the pylorus. Each participant then received a 60 min (t = 0 – 60 min) intraluminal infusion of glucose (3 kcal/min) into either the proximal (< 60 cm “GP”), or the distal (> 70 cm “GD”), or both (i.e. proximal and distal “GPD”), small intestinal segments. Measurements: BP, HR (automated device), superior mesenteric artery (SMA) blood flow (Doppler ultrasound) and plasma noradrenaline (NA). Results: Small intestinal glucose infusion was associated with reductions in systolic (GP: P = 0.004, GD: P = 0.001, GPD: P = 0.001) and diastolic (GP: P = 0.007, GD: P = 0.004, GPD: P = 0.003) BP and increases in HR (GP: P = 0.001, GD: P = 0.001, GPD: P = 0.002) and plasma NA (GP: P = 0.001, GD: P = 0.002, GPD: P = 0.001), without any difference between the three days. Conclusion: In healthy older participants, the effects of small intestinal glucose to decrease BP and increase SMA flow in healthy older participants appear to be independent of the region, or length, of small intestine exposed.

Influence of luminal nutrient composition on hemodynamics and oxygenation in developing intestine

1992 ◽  
Vol 263 (2) ◽  
pp. G254-G260 ◽  
Author(s):  
K. D. Crissinger ◽  
D. L. Burney
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Vascular Resistance ◽  
Corn Oil ◽  
Age Groups ◽  
Older Age ◽  
Intestinal Blood Flow ◽  
Oxygen Extraction ◽  
Age Related

Age-related differences in the intestinal hemodynamic and oxygenation responses to carbohydrate, protein, and lipid were studied in 1-day-, 3-day-, 2-wk-, and 1-mo-old piglets. A branch of the mesenteric vein draining an isolated loop of jejunoileum was used to measure intestinal blood flow, arteriovenous oxygen content difference, and venous and capillary pressure and to calculate oxygen uptake and vascular resistance. Fractionated intestinal flow was measured with radiolabeled microspheres. Measurements were made before and after luminal placement of either 5% glucose, 2.3% casec, or 5% corn oil. In 1-day-old animals, unlike all older age groups, total intestinal blood flow and vascular resistance were unchanged by any nutrient. Fractionated flow to the mucosa/submucosa levels did, however, increase in the intestine of 1-day-old piglets to a similar extent as that in older age groups. Placement of lipid or protein into the lumen led to increased oxygen uptake in all age groups, whereas carbohydrate absorption resulted in no increase in intestinal oxygen consumption in 1- and 3-day-old animals. In 1-day-olds, the increased oxygen consumption was achieved by enhanced oxygen extraction with no change in total blood flow, whereas all other groups demonstrated increases in blood flow and/or oxygen extraction. Compared with a mixed meal, oxygen consumption was not significantly greater for an individual nutrient component.

Regional blood flow in newborn piglets during environmental cold stress

1986 ◽  
Vol 251 (3) ◽  
pp. G308-G313 ◽  
Author(s):  
S. R. Mayfield ◽  
B. S. Stonestreet ◽  
A. M. Brubakk ◽  
P. W. Shaul ◽  
W. Oh
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Small Intestine ◽  
Cold Stress ◽  
Vascular Resistance ◽  
Oxygen Delivery ◽  
Regional Blood Flow ◽  
Arterial Oxygen ◽  
Arterial Oxygen Content ◽  
Newborn Piglets

Regional blood flow, oxygen delivery, and vascular resistance were determined in newborn piglets during a successful homeothermic response to environmental cold stress. Eight 3- to 4-day-old awake piglets were studied in a thermoneutral environment and 30, 45, and 60 min after onset of environmental cold stress. During cold stress, blood flow was significantly increased to skeletal muscle, the thermogenic organ, and decreased to the small intestine (P less than 0.05). Because arterial oxygen content (CaO2) was stable during the study, changes in oxygen delivery (CaO2 X blood flow) paralleled blood flow. Vascular resistance during cold stress was significantly decreased in skeletal muscle and increased in both the adrenals and the small intestine (P less than 0.05). We conclude that, during successful thermogenesis, the redistribution of cardiac output toward the thermogenic organ (skeletal muscle) is associated with a significant decrease in intestinal blood flow and oxygen delivery. This is not a passive process as evidenced by the coincident observation of increased intestinal vascular resistance.

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