Catecholamine and serotonin concentrations in fetal guinea-pig brain: relation to regional cerebral blood flow and oxygen delivery in the growth-restricted fetus

1996 ◽  
Vol 8 (3) ◽  
pp. 355 ◽  
Author(s):  
A Jensen ◽  
HJ Klonne ◽  
A Detmer ◽  
AM Carter
Keyword(s):  
Blood Flow ◽  
Guinea Pig ◽  
Oxygen Delivery ◽  
Oxygen Supply ◽  
Tissue Concentrations ◽  
Blood Flows ◽  
Arterial Blood ◽  
Tissue Po2 ◽  
The Brain ◽  
Neurotransmitter Metabolism

To test the hypothesis that intrauterine growth restriction (IUGR) would lead to altered neurotransmitter metabolism in the brain because of poorer oxygenation, blood flows and tissue concentrations of noradrenaline, dopamine, serotonin and their metabolites were measured in 14 parts of the brain of guinea-pig fetuses at 61-64 days' gestation. Eight fetuses with IUGR induced by uterine artery ligation were compared with 8 controls. Regional brain blood flows were determined by the microsphere method and tissue concentrations of monoamines by HPLC with electrochemical detection. The oxygen content of preductal arterial blood was significantly lower in IUGR fetuses than in controls (2.3 +/- 0.6 v. 3.5 +/- 0.5 mM; P < 0.001). Although this was compensated by increases in blood flow to many areas of the brain, significant decreases occurred in oxygen delivery to the temporal and occipital cortex, hippocampus and cerebellum of IUGR fetuses. In contrast, oxygen delivery to brainstem areas was maintained. Noradrenaline concentrations were closely similar in brains from the two groups, except for an increase in the caudate nucleus of IUGR fetuses. Dopamine concentrations were significantly elevated in brainstem areas. Concentrations of 3,4-dihydroxyphenylglycol (DOPEG), a noradrenaline metabolite, and 3,4-dihydroxyphenylacetic acid (DOPAC), a dopamine metabolite, showed a similar pattern of increase in brains of IUGR fetuses, possibly resulting from increased synthesis of noradrenaline and dopamine rather than from decreased degradation. Concentrations of serotonin were significantly higher in frontal and temporal cortex of IUGR fetuses, and the serotonin metabolite 5-HIAA increased significantly in cortical areas. Changes in neurotransmitter metabolism could not be related to oxygen supply, since serotonin concentrations increased in the forebrain, despite reduced oxygen delivery and the known dependence of tryptophan-5-hydroxylase on tissue PO2, and dopamine levels were elevated in the brainstem, where the oxygen supply was maintained.

Effects of hematocrit variations on regional hemodynamics and oxygen transport in the dog

1980 ◽  
Vol 238 (4) ◽  
pp. H545-H522 ◽  
Author(s):  
F. C. Fan ◽  
R. Y. Chen ◽  
G. B. Schuessler ◽  
S. Chien
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Blood Vessels ◽  
Oxygen Transport ◽  
Oxygen Supply ◽  
Blood Flows ◽  
Regional Hemodynamics ◽  
Regional Blood Flows ◽  
Splenic Vessels ◽  
The Brain

The responses of alterations in regional hemodynamics and oxygen transport rate to hematocrit (Hct) were studied in 20 pentobarbitalized dogs. Hemodilution was carried out by isovolemic exchange with plasma in 12 dogs and the hemoconcentration with packed cells in 8 dogs. The cardiac output and regional blood flows were determined with the microsphere technique. In hemodilution, the increases of blood flow to the myocardium and the brain were out of proportion to the increase of cardiac output; the oxygen supply to the myocardium remained unchanged while that to the brain decreased only slightly. In hemoconcentration, vasodilation occurred in the myocardium and the brain to maintain constant oxygen supply. Splenic vessels had marked vasoconstriction with Hct alteration in either direction. Blood vessels in the liver, intestine, and kidney responded with a milder vasoconstriction and maintained a constant oxygen supply between Hct of 30-55%. Therefore, during Hct alteration, redistribution of blood flow to myocardium and brain occurred. The optimal Hct range for constant oxygen supply was different among various organs.

scholarly journals Regulation of Brain Blood Flow and Oxygen Delivery in Elite Breath-Hold Divers

2014 ◽  
Vol 35 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Christopher K Willie ◽  
Philip N Ainslie ◽  
Ivan Drvis ◽  
David B MacLeod ◽  
Anthony R Bain ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Delivery ◽  
Blood Gases ◽  
Arterial Oxygen ◽  
Breath Hold ◽  
Cerebral Oxygen ◽  
Arterial Oxygen Content ◽  
Arterial Blood ◽  
End Tidal ◽  
The Brain

The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics were measured during maximum dry apneas in elite breath-hold divers ( n=17). To isolate the effects of apnea and IBM from the concurrent changes on ABG, end-tidal forcing (‘clamp’) was then used to replicate an identical temporal pattern of decreasing arterial PO2 (PaO2) and increasing arterial PCO2 (PaCO2) while breathing. End-apnea PaO2 ranged from 23  to 37 mm Hg (30±7 mm Hg). Elevation in mean arterial pressure was greater during apnea than during clamp reaching +54±24% versus 34±26%, respectively; however, CBF increased similarly between apnea and clamp (93.6±28% and 83.4±38%, respectively). This latter observation indicates that during the overall apnea period IBM per se do not augment CBF and that the brain remains sufficiently protected against hypertension. Termination of apnea was not determined by reduced cerebral oxygen delivery; despite 40% to 50% reductions in arterial oxygen content, oxygen delivery was maintained by commensurately increased CBF.

Glucagon increases hepatic oxygen supply-demand ratio in pigs

1987 ◽  
Vol 252 (5) ◽  
pp. G648-G653
Author(s):  
S. Gelman ◽  
E. Dillard ◽  
D. A. Parks
Keyword(s):  
Blood Flow ◽  
Oxygen Supply ◽  
Venous Blood ◽  
Portal Blood Flow ◽  
Arterial Blood Flow ◽  
Blood Flows ◽  
Arterial Blood ◽  
Young Pigs ◽  
Hepatic Venous Blood ◽  
Pentobarbital Sodium Anesthesia

The present study was performed on eight young pigs to test the hypothesis that glucagon increases hepatic oxygen supply to a greater extent than hepatic oxygen uptake, providing a better hepatic oxygen supply-demand relationship. The experiments were performed under pentobarbital sodium anesthesia and controlled ventilation. Splanchnic blood flow was studied using radioactive microspheres. Glucagon was administered in doses of 1 and 5 micrograms X kg-1 X min-1. During glucagon infusion, hepatic arterial blood flow substantially increased, splenic and pancreatic blood flows increased moderately, while stomach and intestinal blood flows, as well as portal blood flow did not change significantly. Shunting of both 9- and 15-micron spheres through preportal tissues did not change significantly. Oxygen content in arterial or portal venous blood did not change significantly, while it increased in hepatic venous blood by 30%. There were no differences in the effects between the doses of glucagon administered. There was no correlation found between changes in hepatic oxygen supply and cardiac output or blood pressure. The changes observed during glucagon administration resulted in an increase in oxygen delivery to the liver and hepatic oxygen supply-uptake ratio.

Preferential streaming of ductus venosus blood to the brain and heart in fetal lambs

1979 ◽  
Vol 237 (6) ◽  
pp. H724-H729 ◽  
Author(s):  
D. I. Edelstone ◽  
A. M. Rudolph
Keyword(s):  
Blood Flow ◽  
Inferior Vena Cava ◽  
Inferior Vena ◽  
Vena Cava ◽  
Ductus Venosus ◽  
Inferior Vena Caval ◽  
Blood Samples ◽  
Blood Flows ◽  
Arterial Blood ◽  
The Brain

In 16 chronically prepared fetal lambs we compared the systemic distribution of ductus venosus blood flow with that of abdominal inferior vena caval blood by simultaneously injecting microspheres labeled with different radionuclides into an umbilical vein and into the abdominal inferior vena cava. A significantly greater proportion of ductus venosus blood flow than of abdominal inferior vena caval blood flow supplied the brain, heart, and upper body; this resulted from streaming of ductus venosus blood flow within the thoracic inferior vena cava with preferential direction of that blood flow through the foramen ovale. Blood flows to upper and lower body structures and placenta calculated from umbilical venous microsphere injections and reference arterial blood samples did not differ from those computed fromabdominal inferior vena caval injections and reference samples. Thus, despite streamline blood flow within the fetal thoracic inferior vena cava, organ blood flows can be accurately measured with either an umbilical venous or an abdominal inferior vena caval injection of microspheres when either is combined with the appropriate reference arterial blood samples.

Excess oxygen delivery during muscle contractions in spontaneously hypertensive rats

1995 ◽  
Vol 78 (1) ◽  
pp. 101-111 ◽  
Author(s):  
J. M. Lash ◽  
H. G. Bohlen
Keyword(s):  
Blood Flow ◽  
Oxygen Saturation ◽  
Oxygen Delivery ◽  
Spontaneously Hypertensive Rats ◽  
Muscle Contractions ◽  
Hypertensive Rats ◽  
Hemoglobin Oxygen Saturation ◽  
Spontaneously Hypertensive ◽  
Tissue Po2 ◽  
Wistar Kyoto

These experiments determined whether a deficit in oxygen supply relative to demand could account for the sustained decrease in tissue PO2 observed during contractions of the spinotrapezius muscle in spontaneously hypertensive rats (SHR). Relative changes in blood flow were determined from measurements of vessel diameter and red blood cell velocity. Venular hemoglobin oxygen saturation measurements were performed by using in vivo spectrophotometric techniques. The relative dilation [times control (xCT)] of arteriolar vessels during contractions was as large or greater in SHR than in normotensive rats (Wistar-Kyoto), as were the increases in blood flow (2 Hz, 3.50 +/- 0.69 vs. 3.00 +/- 1.05 xCT; 4 Hz, 10.20 +/- 3.06 vs. 9.00 +/- 1.48 xCT; 8 Hz, 16.40 +/- 3.95 vs. 10.70 +/- 2.48 xCT). Venular hemoglobin oxygen saturation was lower in the resting muscle of SHR than of Wistar-Kyoto rats (31.0 +/= 3.0 vs. 43.0 +/- 1.9%) but was higher in SHR after 4- and 8-Hz contractions (4 Hz, 52.0 +/- 4.8 vs. 43.0 +/- 3.6%; 8 Hz, 51.0 +/- 4.6 vs. 41.0 +/- 3.6%). Therefore, an excess in oxygen delivery occurs relative to oxygen use during muscle contractions in SHR. The previous and current results can be reconciled by considering the possibility that oxygen exchange is limited in SHR by a decrease in anatomic or perfused capillary density, arteriovenular shunting of blood, or decreased transit time of red blood cells through exchange vessels.

Regional blood flow in the brain and spinal cord of hypothermic rats

1989 ◽  
Vol 257 (3) ◽  
pp. H785-H790
Author(s):  
T. Sakamoto ◽  
W. W. Monafo
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Brain Stem ◽  
Regional Blood Flow ◽  
Experimental Conditions ◽  
Pentobarbital Sodium ◽  
Arterial Blood ◽  
Group A ◽  
Group B ◽  
The Brain

[14C]butanol tissue uptake was used to measure simultaneously regional blood flow in three regions of the brain (cerebral and cerebellar hemispheres and brain stem) and in five levels of the spinal cord in 10 normothermic rats (group A) and in 10 rats in which rectal temperature had been lowered to 27.7 +/- 0.3 degrees C by applying ice to the torso (group B). Pentobarbital sodium anesthesia was used. Mean arterial blood pressure varied minimally between groups as did arterial pH, PO2, and PCO2. In group A, regional spinal cord blood flow (rSCBF) varied from 49.7 +/- 1.6 to 62.6 +/- 2.1 ml.min-1.100 g-1; in brain, regional blood flow (rBBF) averaged 74.4 +/- 2.3 ml.min-1.100 g-1 in the whole brain and was highest in the brain stem. rSCBF in group B was elevated in all levels of the cord by 21-34% (P less than 0.05). rBBF, however, was lowered by 21% in the cerebral hemispheres (P less than 0.001) and by 14% in the brain as a whole (P less than 0.05). The changes in calculated vascular resistance tended to be inversely related to blood flow in all tissues. We conclude that rBBF is depressed in acutely hypothermic pentobarbital sodium-anesthetized rats, as has been noted before, but that rSCBF rises under these experimental conditions. The elevation of rSCBF in hypothermic rats confirms our previous observations.

Relationship between portal venous and hepatic arterial blood flows: spectrum of response

1990 ◽  
Vol 259 (6) ◽  
pp. G1010-G1018 ◽  
Author(s):  
T. Kawasaki ◽  
F. J. Carmichael ◽  
V. Saldivia ◽  
L. Roldan ◽  
H. Orrego
Keyword(s):  
Blood Flow ◽  
Arterial Blood Flow ◽  
Portal Vein Ligation ◽  
Artery Ligation ◽  
Blood Flows ◽  
Arterial Blood ◽  
Group A ◽  
Group B ◽  
The Relationship ◽  
Group D

The relationship between portal tributary blood flow (PBF) and hepatic arterial blood flow (HAF) was studied in awake, unrestrained rats with the radiolabeled microsphere technique. Six distinct patterns of response emerged. In group A (PBF+, HAF 0), ethanol, acetate, glucagon, prostacyclin, and a mixed diet increased PBF without a change in HAF; in group B (PBF+, HAF+), adenosine and histamine increased both PBF and HAF; in group C (PBF 0, HAF+), isoflurane and triiodothyronine did not change PBF but increased HAF; and in group D (PBF-, HAF+), halothane and vasopressin decreased PBF and increased HAF. Acute partial portal vein ligation decreased PBF (56%) and increased HAF (436%). Hypoxia (7.5% O2) decreased PBF (28%) and increased HAF (110%). In group E (PBF+, HAF-), acute hepatic artery ligation increased PBF (35%) and reduced HAF (74%), while in group F (PBF-, HAF-), thyroidectomy reduced PBF and HAF (36 and 47%, respectively). All blood flow responses were accompanied by the expected changes in both portal tributary and hepatic arterial vascular resistances. The data suggest that the portal and hepatic arterial vascular territories have regulatory mechanisms that allow for independent changes.

Maximal vascular leg conductance in trained and untrained men

1987 ◽  
Vol 62 (2) ◽  
pp. 606-610 ◽  
Author(s):  
P. G. Snell ◽  
W. H. Martin ◽  
J. C. Buckey ◽  
C. G. Blomqvist
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Reactive Hyperemia ◽  
Venous Occlusion ◽  
Vascular Conductance ◽  
Blood Flows ◽  
Arterial Blood ◽  
Sedentary Subjects

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.

Fetal cardiac bypass alters regional blood flows, arterial blood gases, and hemodynamics in sheep

1992 ◽  
Vol 263 (3) ◽  
pp. H919-H928 ◽  
Author(s):  
S. M. Bradley ◽  
F. L. Hanley ◽  
B. W. Duncan ◽  
R. W. Jennings ◽  
J. A. Jester ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Gases ◽  
Arterial Blood Gases ◽  
Blood Flows ◽  
Arterial Blood ◽  
Cardiac Bypass ◽  
Regional Blood Flows ◽  
Placental Blood ◽  
Fetal Organs ◽  
Placental Blood Flow

Successful fetal cardiac bypass might allow prenatal correction of some congenital heart defects. However, previous studies have shown that fetal cardiac bypass may result in impaired fetal gas exchange after bypass. To investigate the etiology of this impairment, we determined whether fetal cardiac bypass causes a redistribution of fetal regional blood flows and, if so, whether a vasodilator (sodium nitroprusside) can prevent this redistribution. We also determined the effects of fetal cardiac bypass with and without nitroprusside on fetal arterial blood gases and hemodynamics. Eighteen fetal sheep were studied in utero under general anesthesia. Seven fetuses underwent bypass without nitroprusside, six underwent bypass with nitroprusside, and five were no-bypass controls. Blood flows were determined using radionuclide-labeled microspheres. After bypass without nitroprusside, placental blood flow decreased by 25–60%, whereas cardiac output increased by 15–25%. Flow to all other fetal organs increased or remained unchanged. Decreased placental blood flow after bypass was accompanied by a fall in PO2 and a rise in PCO2. Nitroprusside improved placental blood flow, cardiac output, and arterial blood gases after bypass. Thus fetal cardiac bypass causes a redistribution of regional blood flow away from the placenta and toward the other fetal organs. Nitroprusside partially prevents this redistribution. Methods of improving placental blood flow in the postbypass period may prove critical to the success of fetal cardiac bypass.

Regional circulatory responses to hypocapnia and hypercapnia in bar-headed geese

1986 ◽  
Vol 250 (3) ◽  
pp. R499-R504 ◽  
Author(s):  
F. M. Faraci ◽  
M. R. Fedde
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Pectoral Muscle ◽  
Blood Flows ◽  
Arterial Blood ◽  
Blood Flow Reduction ◽  
Extreme Altitude ◽  
Anser Indicus ◽  
O2 Delivery

To investigate mechanisms that may allow birds to tolerate extreme high altitude (hypocapnic hypoxia), we examined the effects of severe hypocapnia and moderate hypercapnia on regional blood flow in bar-headed geese (Anser indicus), a species that flies at altitudes up to 9,000 m. Cerebral, coronary, and pectoral muscle blood flows were measured using radioactive microspheres, while arterial CO2 tension (PaCO2) was varied from 7 to 62 Torr in awake normoxic birds. Arterial blood pressure was not affected by hypocapnia but increased slightly during hypercapnia. Heart rate did not change during alterations in PaCO2. Severe hypocapnia did not significantly alter cerebral, coronary, or pectoral muscle blood flow. Hypercapnia markedly increased cerebral and coronary blood flow, but pectoral muscle blood flow was unaffected. The lack of a blood flow reduction during severe hypocapnia may represent an important adaptation in these birds, enabling them to increase O2 delivery to the heart and brain at extreme altitude despite the presence of a very low PaCO2.

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