Jejunal adenosine increases during food-induced jejunal hyperemia

1990 ◽  
Vol 258 (3) ◽  
pp. G370-G376 ◽  
Author(s):  
D. R. Sawmiller ◽  
C. C. Chou
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Normal Saline ◽  
Venous Blood ◽  
Adenosine Release ◽  
Adenosine Concentration ◽  
Anesthetized Dogs ◽  
Arterial Plasma ◽  
Induced Changes ◽  
Increased Blood Flow

If adenosine mediates postprandial intestinal hyperemia, increases in local adenosine release must accompany the hyperemia. We tested this by determining jejunal venous and arterial plasma adenosine concentrations, jejunal blood flow, and oxygen consumption before and during placement of normal saline or predigested food plus bile into the jejunal lumen of anesthetized dogs. Adenosine concentrations were measured by high-pressure liquid chromatography. Luminal placement of food significantly increased blood flow (+46%), oxygen consumption (+40%), venous adenosine concentration (+56 nM), and adenosine release (+1.7 nmol.min-1.100 g tissue-1) during the initial 3 min of placement. Whereas blood flow and oxygen consumption remained elevated for the entire 15-min placement period, venous adenosine concentration and release returned to control levels at 7 and 11 min after placement, respectively. Placement of the same volume of normal saline did not significantly alter any variables measured, indicating that the food-induced changes were because of constituents of food. In conclusion, introduction of predigested food into the jejunal lumen significantly increases adenosine releases into the local venous blood during the initial several minutes of food placement. The increased adenosine production and release may play a role in postprandial jejunal hyperemia.

Role of adenosine in postprandial and reactive hyperemia in canine jejunum

1992 ◽  
Vol 263 (4) ◽  
pp. G487-G493 ◽  
Author(s):  
D. R. Sawmiller ◽  
C. C. Chou
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Adenosine Deaminase ◽  
Reactive Hyperemia ◽  
Concentration Difference ◽  
Adenosine Concentration ◽  
Anesthetized Dogs ◽  
Series Of Experiments ◽  
Increased Blood Flow

The role of adenosine in postprandial jejunal hyperemia was investigated by determining the effect of placement of predigested food into the jejunal lumen on blood flow and oxygen consumption before and during intra-arterial infusion of dipyridamole (1.5 microM arterial concn) or adenosine deaminase (9 U/ml arterial concn) in anesthetized dogs. Neither drug significantly altered resting jejunal blood flow and oxygen consumption. Before dipyridamole or deaminase, food placement increased blood flow by 30-36%, 26-42%, and 21-46%, and oxygen consumption by 13-22%, 21-22%, and 26-29%, during 0- to 3-, 4- to 7-, and 8- to 11-min placement periods, respectively. Adenosine deaminase abolished the entire 11-min hyperemia, whereas dipyridamole significantly enhanced the initial 7-min hyperemia (45-49%). Both drugs abolished the initial 7-min food-induced increase in oxygen consumption. Dipyridamole attenuated (14%), whereas deaminase did not alter (28%), the increased oxygen consumption that occurred at 8-11 min. Adenosine deaminase also prevented the food-induced increase in venoarterial adenosine concentration difference. In separate series of experiments, luminal placement of food significantly increased jejunal lymphatic adenosine concentration and release. Also, reactive hyperemia was accompanied by an increase in venous adenosine concentration and release. This study provides further evidence to support the thesis that adenosine plays a role in postprandial and reactive hyperemia in the canine jejunum.

Effects of dipyridamole on myocardial adenosine and active hyperemia

1984 ◽  
Vol 247 (5) ◽  
pp. H804-H810 ◽  
Author(s):  
R. M. Knabb ◽  
J. M. Gidday ◽  
S. W. Ely ◽  
R. Rubio ◽  
R. M. Berne
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Steady State ◽  
Myocardial Oxygen Consumption ◽  
Cardiac Work ◽  
Adenosine Release ◽  
Adenosine Uptake ◽  
Adenosine Concentration ◽  
The Relationship ◽  
Perfused Hearts

Dipyridamole, a vasodilator that potentiates the actions of exogenous adenosine, is known to inhibit cellular uptake of adenosine, but its effects on cellular adenosine release, and thus interstitial adenosine levels, are disputed. We used the accumulation of adenosine in pericardial infusates (PCI) as an index of interstitial adenosine concentration and observed the effects of dipyridamole on relationships among coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and PCI adenosine concentrations during steady-state alterations of cardiac work. Dipyridamole increased CBF and PCI adenosine concentration without altering MVO2. The relationship between PCI adenosine and CBF was unaltered, supporting a cause and effect relationship between interstitial adenosine concentration and CBF. In addition, we determined that unlike previous studies in isolated perfused hearts the washout of adenosine by coronary plasma was unaffected by dipyridamole. The results support previous suggestions that, whereas dipyridamole inhibits adenosine uptake, it does not alter cellular adenosine release, and therefore interstitial adenosine levels are increased. The constant relationship between PCI adenosine and CBF supports hypotheses that attribute the hyperemias associated with increased cardiac work or with dipyridamole to increased interstitial adenosine.

Vascular responses of dura mater

1989 ◽  
Vol 257 (1) ◽  
pp. H157-H161 ◽  
Author(s):  
F. M. Faraci ◽  
K. A. Kadel ◽  
D. D. Heistad
Keyword(s):  
Blood Flow ◽  
Substance P ◽  
Dura Mater ◽  
Sympathetic Nerves ◽  
Vascular Headache ◽  
Vascular Responses ◽  
Anesthetized Dogs ◽  
High Level ◽  
The Brain ◽  
Increased Blood Flow

The goal of this study was to examine vascular responses of the dura mater. Microspheres were used to measure blood flow to the dura and brain in anesthetized dogs. Under control conditions, blood flow to the dura was 38 +/- 3 (SE) ml.min-1.100 g-1. Values for blood flow to the dura obtained with simultaneous injection of 15- and 50-microns microspheres were similar, which suggests that shunting of 15-microns spheres was minimal. Left atrial infusion of substance P (100 ng.kg-1.min-1) and serotonin (40 micrograms.kg-1.min-1), two agonists that have been reported to increase vascular permeability in the dura, increased blood flow to the dura two- to threefold. Adenosine (iv) produced vasodilatation in the dura. Adenosine and serotonin did not affect cerebral blood flow, but substance P increased blood flow to the brain by approximately 40%. Seizures, which produce pronounced dilatation of cerebral vessels despite activation of sympathetic nerves, produced vasoconstriction in the dura. Thus 1) the dura is perfused at a relatively high level of blood flow under normal conditions and is very responsive to vasoactive stimuli, and 2) substance P and serotonin, which have been implicated in the pathogenesis of vascular headache, produce pronounced vasodilator responses in the dura mater.

Hemodynamics and metabolism of the in vivo vascularly isolated canine pancreas.

1979 ◽  
Vol 236 (6) ◽  
pp. E626
Author(s):  
R J Alteveer ◽  
M J Jaffe ◽  
J Van Dam
Keyword(s):  
Blood Flow ◽  
Glucose Uptake ◽  
Venous Blood ◽  
Fatty Acid Uptake ◽  
Acid Uptake ◽  
Anesthetized Dogs ◽  
Metabolic Variables ◽  
The Stability ◽  
First Time

Surgical procedures are detailed that have yielded for the first time an in vivo vascularly isolated, autoperfused preparation of the entire pancreas in anesthetized dogs. Previous studies had isolated only part of the pancreas or had resorted to blood-flow techniques not requiring pooled pancreatic venous blood, necessary for metabolic studies of the organ. Pancreatic blood flow (48 ml/min), O2 uptake (180 mumol/min), glucose uptake (51.0 mumol/min), lactate output (6.6 mumol/min), net free fatty acid uptake (2.23 mumol/min), all per 100 g tissue, and various other measured and calculated hemodynamic and metabolic variables were determined on the preparation during control conditions. The stability of the preparation was verified by serial determinations of these parameters and of blood alpha-amylase and beta-glucuronidase levels from 1 to 2.5 h postsurgery. Metabolic rate and glucose uptake were both found to be much higher than in intestinal tissues and approached values characteristic of liver tissue.

Effect of solute-coupled volume absorption on oxygen consumption in cat ileum.

1979 ◽  
Vol 236 (2) ◽  
pp. E198
Author(s):  
J D Valleau ◽  
D N Granger ◽  
A E Taylor
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Glucose Absorption ◽  
Tyrode Solution ◽  
Recovery Method ◽  
Volume Absorption ◽  
All Solutions ◽  
Volume Recovery ◽  
Oxygen Requirements ◽  
Increased Blood Flow

The effects of solute-coupled volume absorption on blood flow, oxygen consumption, and vascular resistance were analyzed in autoperfused segments of cat ileum. Intestinal absorption was stimulated by placing either Tyrode solution, Tyrode + glucose, or Tyrode + taurocholate into the ileal lumen. Net volume absorption rates (Jv,m) were determined using a volume recovery method. Oxygen consumption (VO2) increased during the absorption of all solutions. The absorption of Tyrode solution plus glucose caused the greatest increase in VO2, whereas Tyrode plus taurocholate resulted in the smallest increase. For Tyrode solution and Tyrode plus glucose absorption, the increased VO2 was due predominantly to an increased blood flow, whereas the increased VO2 with taurocholate resulted from an increased oxygen extraction. A linear relationship between the change in VO2 during transport and Jv,m was aquired for Tyrode solution, and Tyrode + glucose. The results indicate that the oxygen requirements of the absorbing intestine are dependent on both the rate of transport and the solutes being transported.

Renal vascular response to amino acids: effect of pancreatectomy

1990 ◽  
Vol 258 (5) ◽  
pp. F1154-F1163 ◽  
Author(s):  
A. J. Premen ◽  
D. A. Powell ◽  
R. G. Carroll ◽  
D. E. Dobbins
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Filtration Rate ◽  
Plasma Glucagon ◽  
Vascular Response ◽  
Incremental Change ◽  
Renal Hemodynamic ◽  
Anesthetized Dogs ◽  
Arterial Plasma ◽  
Renal Vascular

We ascertained the importance of glucagon in modulating the renal hemodynamic response to amino acid (AA) infusion in anesthetized dogs. In controls (n = 6), AAs (L-serine, alanine, and proline; 0.051 mmol.kg-1.min-1 iv) elevated renal blood flow (RBF) and glomerular filtration rate (GFR) by 35 and 34%, respectively, while elevating arterial plasma glucagon-like immunoreactivity (AGLI) by 96 pmol/l. In control pancreatectomized (PX) dogs (n = 6), all parameters remained at control values over 2 h. In PX dogs, AAs (n = 6) failed to reproduce the renal hemodynamic and AGLI responses elicited by AAs in controls. In PX dogs infused with AAs, replacement of AGLI (n = 6) to an incremental plasma level of 111 pmol/l, a level no different than that produced by AAs in controls, elevated RBF and GFR by 25 and 26.5%, respectively. These hemodynamic responses were 71 and 78%, respectively, of the total responses elicited by AAs in controls. In PX dogs infused with glucagon alone (0.86 pmol.kg-1.min-1; n = 6), an incremental change in AGLI of 112 pmol/l was accompanied by only small increases in RBF and GFR (9%). These data suggest the importance of glucagon in modulating the renal hyperemia and hyperfiltration ascribed to AA infusion in anesthetized dogs.

Effect of hand heating by a warm air box on O2 consumption of the contralateral arm

1992 ◽  
Vol 72 (6) ◽  
pp. 2364-2368 ◽  
Author(s):  
E. E. Blaak ◽  
M. A. Van Baak ◽  
K. P. Kempen ◽  
W. H. Saris
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Skin Temperature ◽  
Forearm Blood Flow ◽  
Venous Blood ◽  
Oral Glucose ◽  
Glucose Load ◽  
Glucose Intake ◽  
Integrated Response

Arterialization of venous blood is often used in studying forearm metabolism. Astrup et al. [Am. J. Physiol. 255 (Endocrinol. Metab. 18): E572-E578, 1988] showed that heating of the hand by a warming blanket caused a redistribution of blood flow in the contralateral arm and thus introduced errors in forearm skeletal muscle flux calculations. The present study was undertaken to investigate how hand heating by a warm air box (60 degrees C) would affect metabolism and blood flow in the contralateral arm before and during 3 h after a glucose load. Eleven healthy volunteers (5 males, 6 females) underwent an oral glucose tolerance test (70 g) on two different occasions, one test with and one without heating of the contralateral hand, in random order. Heating the hand for 30 min before glucose intake did not affect skin temperature, rectal temperature, deep venous oxygen saturation, forearm blood flow, or oxygen consumption of forearm skeletal muscle. Although, after the glucose load, heating significantly increased forearm blood flow (P less than 0.05), the integrated response after glucose was not significantly different between control and heating experiments [67 +/- 43 and 117 +/- 41 (SE) ml/100 ml tissue]. With both conditions, there was an increase in skin temperature (P less than 0.001, integrated response control: 369 +/- 79 and heating: 416 +/- 203 degrees C) and oxygen consumption of forearm muscle (control: 290 +/- 73, P less than 0.05 and heating: 390 +/- 130 mumol/100 ml, P less than 0.05) after glucose intake. These responses did not significantly differ between the conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of coupling between adrenal cortical metabolic activity and blood flow in anesthetized dogs

1992 ◽  
Vol 262 (1) ◽  
pp. 1-1
Author(s):  
N. T. Sakima ◽  
M. J. Breslow ◽  
H. Raff ◽  
R. J. Traystman
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Adrenal Gland ◽  
Metabolic Activity ◽  
Anesthetized Dogs

Pages H410–H415: N. T. Sakima, M. J. Breslow, H. Raff, and R. J. Traystman. “Lack of coupling between adrenal cortical metabolic activity and blood flow in anesthetized dogs.” Page H412: The units for oxygen consumption in Fig. 3 should read as cc O2/min/100 g adrenal gland.

Hemodynamic responses to induced tachycardia in methylene blue-treated dogs

1964 ◽  
Vol 206 (6) ◽  
pp. 1279-1280 ◽  
Author(s):  
Skoda Afonso ◽  
George G. Rowe ◽  
Cesar A. Castillo ◽  
Charles W. Crumpton
Keyword(s):  
Methylene Blue ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Right Ventricular ◽  
Coronary Circulation ◽  
Coronary Vascular Resistance ◽  
Hemodynamic Effects ◽  
Group I ◽  
Anesthetized Dogs ◽  
Group Ii

The present study relates to metabolic, and systemic and coronary hemodynamic effects of methylene blue in five anesthetized dogs (group I) and of electrically induced tachycardia in ten dogs pretreated with methylene blue (group II). In group I body oxygen consumption increased slightly. In group II coronary blood flow, cardiac metabolic rate for oxygen, and right ventricular work increased significantly while coronary vascular resistance decreased significantly. The observed pattern of changes is not different from that produced by induced tachycardia in untreated dogs. Methylene blue does not alter the usual response of coronary circulation to cardiac acceleration.

Aminophylline and interstitial adenosine during sustained exercise hyperemia

1986 ◽  
Vol 251 (6) ◽  
pp. H1232-H1243 ◽  
Author(s):  
L. P. Thompson ◽  
M. W. Gorman ◽  
H. V. Sparks
Keyword(s):  
Interstitial Fluid ◽  
Standard Dose ◽  
Adenosine Release ◽  
Adenosine Receptor Antagonist ◽  
Adenosine Concentration ◽  
Exercise Hyperemia ◽  
Before And After ◽  
Exercise Period ◽  
Arterial Plasma ◽  
Plasma Adenosine

We tested the hypothesis that an increase in interstitial fluid (ISF) adenosine concentration contributes to vasodilation of high oxidative skeletal muscle during sustained free-flow exercise. Canine calf muscles were stimulated at 3 Hz for 10 min before and after the infusion of the adenosine receptor antagonist aminophylline (10 mg/kg). The vasodilation that occurred during aminophylline infusion was allowed to decay before the postaminophylline exercise period was begun. This dose of aminophylline shifted the response to infused adenosine 20-fold during rest and reduced the response to a standard dose by 90% during exercise. Aminophylline had no significant effect on blood flow or on O2 consumption at rest or during exercise. Adenosine release (venous minus arterial plasma concentration times plasma flow) increased during 3-Hz exercise both before and after aminophylline infusion, but venous plasma adenosine concentration did not increase in either case. We developed a mathematical model of adenosine movement between ISF and plasma to help us judge whether to use adenosine release or venous concentration as an index of ISF adenosine and decided that venous concentration should be used. We conclude that aminophylline has no effect on sustained 3-Hz exercise hyperemia because under these conditions ISF adenosine concentration does not increase.

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