Effect of enkephalins on cardiac output and regional blood flow in conscious dogs

1989 ◽  
Vol 256 (6) ◽  
pp. H1651-H1658
Author(s):  
C. L. Rosen ◽  
A. Cote ◽  
G. G. Haddad
Keyword(s):  
Skeletal Muscle ◽  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Base Line ◽  
Brain Blood Flow ◽  
O2 Consumption ◽  
Blood Gas ◽  
Blood Flow Redistribution

To investigate the effects of enkephalins on cardiac output and regional blood flow, we administered D-Ala-D-Leu-enkephalin (DADLE) intracisternally (ic) to 14 chronically instrumented unanesthetized dogs. Measurements were made at base line, 20, 45, and 75 min after DADLE (25 or 125 micrograms/kg) and 15 min after naloxone (5 micrograms/kg ic). After 125 micrograms/kg DADLE, all animals developed hypoventilation, bradycardia, and decreased O2 consumption without hypotension. Cardiac output decreased (-34%), but brain blood flow increased (+110%). Blood flow decreased to the diaphragm (-38%), heart (-21%), skeletal muscle (-40%), skin (-67%), pancreas (-79%), and gastrointestinal tract (-26%). After 25 micrograms/kg DADLE, there were no consistent changes in cardiac output or regional blood flow. Four additional animals (without DADLE) were exposed to altered inspired gases to reproduce the blood gas changes after DADLE. These animals developed hyperventilation without bradycardia and increased brain (+114%) and diaphragm (+649%) blood flow. We conclude that centrally administered enkephalins produce 1) a parallel decrease in ventilation, heart rate, O2 consumption, and cardiac output and 2) a major blood flow redistribution, primarily dictated by the effects of opioids on ventilation, heart rate, and metabolism.

Exercise, dobutamine, and combined atropine, norepinephrine, and epinephrine compared

1985 ◽  
Vol 58 (6) ◽  
pp. 2047-2053 ◽  
Author(s):  
G. C. Haidet ◽  
T. I. Musch ◽  
G. A. Ordway ◽  
J. H. Mitchell
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Myocardial Blood Flow ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Submaximal Exercise ◽  
O2 Consumption ◽  
Double Product ◽  
Total Body

We compared the cardiovascular effects evoked in conscious dogs by 1) submaximal exercise; 2) infusion of dobutamine (40 micrograms X kg-1 X min-1); and 3) infusion of a combination of atropine (0.15 mg/kg), norepinephrine (0.19 micrograms X kg-1 X min-1), and epinephrine (0.05 micrograms X kg-1 X min-1). Myocardial O2 demand, as estimated by the double product (heart rate X systolic blood pressure), was similar during all three interventions. Cardiac output and heart rate increased significantly (P less than 0.05) during each of the three interventions. Arteriovenous O2 difference and total body O2 consumption, however, increased only during submaximal exercise. Although myocardial blood flow increased similarly during each of the three interventions, blood flow to skeletal muscle and the tongue increased only during exercise. Exercise and the combined infusion of atropine, norepinephrine, and epinephrine produced similar increases in blood flow to the diaphragm and similar decreases in blood flow to the stomach. These changes in blood flow were associated with appropriate changes in vascular resistance. Additionally, blood flow to the brain, kidney, adrenal glands, liver, and intestine did not change during any of the three interventions. Thus, in dogs, submaximal exercise, infusion of dobutamine, and infusion of a combination of atropine, norepinephrine, and epinephrine to evoke a given level of estimated myocardial O2 consumption produce similar increases in cardiac output, heart rate, and myocardial blood flow. In contrast, the changes in total body O2 consumption, arteriovenous O2 difference, regional blood flow, and regional vascular resistance that occur during each of these three interventions are different.

scholarly journals Functional impairment of skeletal muscle oxidative metabolism during knee extension exercise after bed rest

2011 ◽  
Vol 111 (6) ◽  
pp. 1719-1726 ◽  
Author(s):  
Desy Salvadego ◽  
Stefano Lazzer ◽  
Mauro Marzorati ◽  
Simone Porcelli ◽  
Enrico Rejc ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Oxidative Metabolism ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Bed Rest ◽  
Knee Extension ◽  
Functional Evaluation

A functional evaluation of skeletal muscle oxidative metabolism during dynamic knee extension (KE) incremental exercises was carried out following a 35-day bed rest (BR) (Valdoltra 2008 BR campaign). Nine young male volunteers (age: 23.5 ± 2.2 yr; mean ± SD) were evaluated. Pulmonary gas exchange, heart rate and cardiac output (by impedance cardiography), skeletal muscle (vastus lateralis) fractional O2 extraction, and brain (frontal cortex) oxygenation (by near-infrared spectroscopy) were determined during incremental KE. Values at exhaustion were considered “peak”. Peak heart rate (147 ± 18 beats/min before vs. 146 ± 17 beats/min after BR) and peak cardiac output (17.8 ± 3.3 l/min before vs. 16.1 ± 1.8 l/min after BR) were unaffected by BR. As expected, brain oxygenation did not decrease during KE. Peak O2 uptake was lower after vs. before BR, both when expressed as liters per minute (0.99 ± 0.17 vs. 1.26 ± 0.27) and when normalized per unit of quadriceps muscle mass (46.5 ± 6.4 vs. 56.9 ± 11.0 ml·min−1·100 g−1). Skeletal muscle peak fractional O2 extraction, expressed as a percentage of the maximal values obtained during a transient limb ischemia, was lower after (46.3 ± 12.1%) vs. before BR (66.5 ± 11.2%). After elimination, by the adopted exercise protocol, of constraints related to cardiovascular O2 delivery, a decrease in peak O2 uptake and muscle peak capacity of fractional O2 extraction was found after 35 days of BR. These findings suggest a substantial impairment of oxidative function at the muscle level, “downstream” with respect to bulk blood flow to the exercising muscles, that is possibly at the level of blood flow distribution/O2 utilization inside the muscle, peripheral O2 diffusion, and intracellular oxidative metabolism.

Cardiac output distribution and regional blood flow during hypocarbia in monkeys

1985 ◽  
Vol 58 (4) ◽  
pp. 1225-1230 ◽  
Author(s):  
S. Gelman ◽  
K. C. Fowler ◽  
S. P. Bishop ◽  
L. R. Smith
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Arterial Blood Flow ◽  
Tissue Blood Flow ◽  
Base Line ◽  
Output Distribution ◽  
Arterial Blood ◽  
Cardiac Output Distribution ◽  
The Brain

Cardiac output distribution and regional blood flow were studied during hypocarbia independent of changes in ventilatory parameters. Fifteen cynomolgus monkeys were anesthetized with methohexital sodium (8 mg/kg im) and hyperventilated through an endotracheal tube. Hypocarbia at two levels, 28 +/- 1.8 and 17 +/- 0.6 Torr, was achieved by a stepwise decreasing CO2 flow into the semiclosed system. Regional blood flow was determined with labeled microspheres. At each stage of experiments two sets of microspheres (9 and 15 microns diam) were used simultaneously. The use of two microsphere sizes allowed evaluation of the relationship between total (nutritive and nonnutritive) tissue blood flow, determined with 15-microns spheres, and nutritive blood flow, determined with 9-microns spheres. There was no change in cardiac output or arterial pressure during both degrees of studied hypocarbia. Hypocarbia was accompanied by a decrease in myocardial blood flow determined with 15-microns spheres and preservation of the flow determined with 9-microns spheres. Splenic blood flow was decreased, whereas hepatic arterial blood flow was increased during both levels of hypocarbia. Blood flow through the brain, renal cortex, and gut showed a biphasic response to hypocarbia: during hypocarbia at 28 +/- 1.8 Torr, blood flow determined with 15-microns spheres was unchanged (in the gut) or decreased (in the brain and kidneys), whereas blood flow determined with 9-microns spheres was decreased. During hypocarbia at 17 +/- 0.6 Torr, blood flow determined with 9-microns spheres had a tendency to restore to base-line values.

Pulmonary and circulatory changes in conscious sheep exposed to 100% O2 at 1 ATA

1982 ◽  
Vol 53 (1) ◽  
pp. 110-116 ◽  
Author(s):  
S. Matalon ◽  
M. S. Nesarajah ◽  
L. E. Farhi
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Partial Pressure ◽  
Regional Blood Flow ◽  
Respiratory Acidosis ◽  
Right Atrial ◽  
Base Line ◽  
Co2 Partial Pressure ◽  
O2 Partial Pressure ◽  
Mixed Venous

We have measured the effects of normobaric hyperoxia on arterial and mixed venous gas tensions, cardiac output, heart rate, right atrial, pulmonary, and aortic pressures in 12 conscious chronically instrumented sheep. Regional blood flow to brain, heart, kidney, intestines, and respiratory muscles was assessed in five sheep by injecting 15-micrometers microspheres labeled with gamma-emitting isotopes. Survival time ranged from 60 to 120 h (mean = 80 h). All variables except arterial O2 partial pressure (PaO2) and mixed venous O2 partial pressure remained at base-line level during the first 40 h of exposure, after which PaO2 decreased gradually but remained above 200 Torr at death. After this there was a progressive uncompensated respiratory acidosis with terminal arterial CO2 partial pressure values exceeding 90 Torr. There was a considerable rise in the brain blood flow, whereas flow to the other organs either remained unchanged or increased in proportion to cardiac output. Our experiments also showed that systemic hyperoxic vasoconstriction did not occur, and any local changes were not of sufficient magnitude to affect perfusion.

Postnatal changes in regional blood flow during cold-induced shivering in sow-reared piglets

1999 ◽  
Vol 77 (6) ◽  
pp. 414-421 ◽  
Author(s):  
Gaëlle Lossec ◽  
Claude Duchamp ◽  
Yves Lebreton ◽  
Patrick Herpin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Output ◽  
Heat Production ◽  
Cold Exposure ◽  
Cardiovascular Response ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Cold Challenge ◽  
Shivering Thermogenesis

To determine whether newborn pigs are able to display adequate cardiovascular adjustments favouring shivering thermogenesis in skeletal muscles soon after birth, regional blood flow and fractional distribution of cardiac output were determined in 1-day-old (n = 6) and 5-day-old (n = 6) conscious piglets at thermal neutrality and during cold exposure, using coloured microspheres. Five-day-old piglets stayed with the sow before the experiment. The cold challenge was designed to induce a similar increase (~+90%) in heat production at both ages. Skeletal muscle blood flow increased with both age (p < 0.05) and cold exposure (p < 0.001), with the effect of cold being more pronounced in 5-day-old piglets than in 1-day-old piglets (+60%, p < 0.05). The difference between individual muscles increased with age, with fractional blood flow being 41% higher in rhomboideus than in longissimus thoracis muscle during cold exposure in 5-day-old piglets (p < 0.05). Cardiac output was similar at both ages and increased by 23% in the cold (p < 0.001). At 1 day of age, there was no redistribution of cardiac output among the internal organs during the cold challenge, while at 5 days of age, the increase in muscle fractional blood flow was associated with a reduction (p < 0.05) in the fraction of cardiac output reaching the skin (-24%), the small intestine (-21%), and the liver (-20%). In conclusion, these results suggest that there is a rapid postnatal improvement of cardiovascular adjustments favouring blood perfusion and probably heat production during cold-induced shivering in the most oxidative muscles studied. This cardiovascular response may play a role in the postnatal enhancement of thermoregulation in piglets.Key words: skeletal muscle, blood distribution, shivering thermogenesis, piglet, age.

scholarly journals Effects of Thiopental on Regional Blood Flows in the Rat

1996 ◽  
Vol 84 (3) ◽  
pp. 596-604 ◽  
Author(s):  
Russell D. Wada ◽  
Hideyoshi Harashima ◽  
William F. Ebling ◽  
Eileen W. Osaki ◽  
Donald R. Stanski
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Plasma Concentrations ◽  
Brain Blood Flow ◽  
Blood Gas ◽  
Fat Tissue ◽  
Blood Flows ◽  
Hypnotic Effect ◽  
Regional Blood Flows ◽  
Arterial Plasma

Background The goal of this investigation was to characterize the effects of thiopental on cardia output and regional blood flows in the rat. Blood flows influence thiopental pharmacokinetics. Acquisition of these data may ultimately permit evaluation of the contribution of thiopental-induced alterations in regional blood flows to the disposition and hypnotic effect of this drug. Methods Chronically instrumented unrestrained Wistar rats (n=20) aged 3-4 months received either a dose of thiopental sufficient to induce a brief period of unconsciousness (20 mg.kg(-1)) or a larger dose achieving electroencephalographic burst suppression (45 mg.kg(-1)). Cardiac output and blood flows to 14 tissues were determined at 4 times in each rat for a period of 420 min using injections of radioactive microspheres (expressed as mean +/- SD). Mean arterial pressure, heart rate, and blood gas tensions were determined at all measurement times. Arterial plasma concentrations were sampled at postinfusion times. Results No important changes in systemic cardiovascular measurements were detected after the smaller dose of thiopental. One minute after the larger dose, cardiac output decreased from baseline (123 +/- 14 to 84 +/- ml.min (-1), P&lt; 0.01), flow to muscle and fat decreased, and muscle and fat resistance increased. At 5 min, compared to baseline, no difference in cardiac output was detected (123 +/- vs. 119 +/- ml.min (-1)), intestinal flows increased and intestinal resistances decreased. Cardiac output was again depressed at 30, 90, and 180 min. Brain blood flow decreased 25 +/- 19 % (P&lt; 0.01) from baseline for the duration of the study. Conclusions Thiopental acutely decreases cardiac output, and blood flows to muscle and fat tissue. The temporary return of cardiac output to baseline may be related to intestinal vasodilation. These blood flow alterations may influence the pharmacokinetics of thiopental.

Isoproterenol and myocardial O2 supply/consumption in hypertension-induced myocardial hypertrophy

1990 ◽  
Vol 259 (2) ◽  
pp. H346-H351
Author(s):  
C. M. Cimini ◽  
H. R. Weiss
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Coronary Blood Flow ◽  
Myocardial Hypertrophy ◽  
Base Line ◽  
Animal Groups ◽  
O2 Supply ◽  
And Function ◽  
Isoproterenol Infusion

Myocardial oxygen supply, O2 consumption (MVO2) and function were determined during base-line and isoproterenol infusion (0.5 microgram.kg-1.min-1) 30 days after New Zealand White rabbits were prepared as one-kidney, one-clip (1K,1C) Goldblatt hypertensive or uninephrectomized (sham) controls. Coronary blood flow and cardiac output, using radioactive microspheres, and small vessel O2 saturations, using microspectrophotometry, were measured in hypertrophied and nonhypertrophied hearts. After 30 days, 33% myocardial hypertrophy was evident in the 1K,1C animals. Base-line blood pressure was significantly higher in the 1K,1C animals compared with sham controls and remained higher during isoproterenol infusion. Base-line heart rate was not different between animal groups, and heart rate increased in both groups during isoproterenol. Cardiac output was similar between sham and 1K,1C animals during base-line conditions (316 +/- 40 vs. 365 +/- 51 ml/min, respectively). After isoproterenol, cardiac output increased in the sham animals (494 +/- 119 ml/min) but not in the 1K,1C group (317 +/- 85 ml/min). Isoproterenol elevated MVO2 threefold in both the sham and 1K,1C animals. Coronary blood flow was significantly increased to similar levels in both animal groups. O2 extraction significantly increased during isoproterenol in both groups. Therefore, impaired cardiac function was evident during isoproterenol stress in the hypertrophied myocardium independent of myocardial O2 supply or consumption restrictions.

Total and regional cerebral blood flow during moderate and severe exercise in miniature swine

1976 ◽  
Vol 40 (2) ◽  
pp. 191-195 ◽  
Author(s):  
D. L. Foreman ◽  
M. Sanders ◽  
C. M. Bloor
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Cerebral Blood Flow ◽  
White Matter ◽  
Regional Blood Flow ◽  
Aortic Pressure ◽  
Miniature Swine ◽  
Regional Flow ◽  
Severe Exercise

To determine the influence of exercise on cerebral blood flow, we ran 14 swine at 3–6 mph and at 0–10% grades on a treadmill for 30 min at moderate and severe levels of exercise. Measuring heart rate, cardiac output, and aortic pressure via implanted probes, we injected 15-mum radiolabeled microspheres via the left atrium before and during exercise. We measured their distribution by gamma spectrometry, determining total cerebral blood flow, regional blood flow, and ratio of flow to gray and white matter. Heart rate, cardiac output, and aortic pressure rose progressively with increasing exercise. Total cerebral flow resembled that reported in humans, i.e., it did not change significantly with exercise. Regional flow distribution also failed to change significantly with exercise. The ratio of gray to white matter flow did not change except to the cerebellum where it rose significantly from resting values at both moderate and severe exercise. Gray matter received more flow than white matter during all three conditions of observation. Cerebral blood flow was remarkably constant during even severe exercise.

Effects of angiotensin, vasopressin, and methoxamine on cardiac function and blood flow distribution in conscious dogs

1976 ◽  
Vol 231 (5) ◽  
pp. 1579-1587 ◽  
Author(s):  
GR Heyndrickx ◽  
DH Boettcher ◽  
SF Vatner
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Left Ventricular ◽  
Blood Flow Distribution ◽  
Cardiac Rate ◽  
Differential Effects ◽  
Differential Pattern

A comparison was made of the effects of vasopressin (ADH), methoxamine (MX), and angiotensin II (AN) on coronary and left ventricular dynamics, cardiac output, and regional blood flow distribution in intact, consci9us dogs. At an equal percent pressure elevation, ADH reduced cardiac output and cardiac rate the most, while AN had the least effect. After denervation of arterial baroreceptors, ADH still reduced heart rate, while AN increased it, suggesting nonbaroreceptor negative and positive chronotropic effects, respectively. A differential pattern on peak dP/dt was also observed, with ACH causing a greater reduction than MX while AN did not decrease dP/dt. With heart rate held constant, AN did not reduce dP/dt, suggesting a direct positive inotropic effect since dP/dt should have fallen slightly due to reflex mechanisms, as was observed with MX and ADH. ADH induced the greatest increase in coronary resistance (140%), while the least (46%) was observed with AN, which could be explained, in part, by the differential effects observed on cardiac rate and contractility. The greatest increase in resistance in the iliac bed occurred with ADH (30%), and the least with AN (34%). Conversely, the greatest constriction in the renal bed occurred with AN (95%), and lesser amounts were observed with ADH (36%) and MX (35%). Thus ADH, MX, and AN exert potent yet differential vasoconstricting actions on peripheral beds. In addition, while all three agents elicited coronary vasoconstriction, the differential effects on coronary vascular resistance appeared to be due predominantly to a difference in chronotropic and inotropic actions.

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