NO modulates fetoplacental blood flow distribution and whole body oxygen extraction in fetal sheep

1998 ◽  
Vol 274 (5) ◽  
pp. R1331-R1337 ◽  
Author(s):  
Joseph J. Smolich
Keyword(s):  
Blood Flow ◽  
Flow Distribution ◽  
The Body ◽  
Whole Body ◽  
Blood Flow Distribution ◽  
Relative Level ◽  
Fetal Sheep ◽  
Placental Perfusion ◽  
Blood Flows ◽  
Placental Blood

It is unknown if nitric oxide (NO) influences the relative level of the left (LV) and right ventricular (RV) outputs, the blood flow distribution between the body and placenta, or whole body O2extraction and O2 consumption in the fetus. To address these questions eight fetal lambs were chronically instrumented at 128–134 days gestation (term 147 days), and blood flows were measured with radioactive microspheres 3–4 days later at baseline and after inhibition of NO synthesis with N ω-nitro-l-arginine (l-NNA, 10 and 25 mg/kg iv).l-NNA progressively reduced the combined ventricular output ( P < 0.005) but did not alter the relative levels of the LV and RV outputs. Fetal body blood flow fell by 31% after 10 mg/kgl-NNA ( P < 0.005), but a reduction in placental blood flow ( P < 0.005) was smaller (20%) and not observed until 25 mg/kgl-NNA. Whole body O2 extraction increased by 71% after 10 mg/kg l-NNA ( P < 0.005) and did change further at 25 mg/kg l-NNA, whereas whole body O2 consumption rose by 15% at 10 mg/kg l-NNA ( P < 0.05) and returned to baseline at 25 mg/kg l-NNA. These results suggest that, as well as reducing the combined ventricular output, inhibition of fetal NO synthesis redistributes systemic blood flow toward the placenta and increases fetal body O2 extraction. The latter initially increases whole body O2consumption and then maintains it at near baseline levels after a fall in placental perfusion.

NO supports right ventricular flow dominance and whole body O2 utilization in midgestation fetal lambs

2001 ◽  
Vol 280 (4) ◽  
pp. R1016-R1022 ◽  
Author(s):  
Joseph J. Smolich
Keyword(s):  
Blood Flow ◽  
Flow Distribution ◽  
The Body ◽  
Whole Body ◽  
Blood Flow Distribution ◽  
Blood Flows ◽  
Blood Flow Ratio ◽  
Placental Blood ◽  
Flow Changes ◽  
Placental Blood Flow

It is unknown if nitric oxide (NO) modulates the relative levels of left (LV) and right (RV) ventricular output, fetal O2 consumption, or blood flow distribution between the body and placenta at midgestation. To address these questions, six fetal lambs were instrumented at 89–96 days gestation (term 147 days), and blood flows were measured with radioactive microspheres 3–4 days later at baseline and after inhibition of NO synthesis with 10 mg/kg (l-NNA10) and 25 mg/kg (l-NNA25) N ω-nitro-l-arginine. LV output fell by 74 ± 15 ml · min−1 · kg−1 atl-NNA10 ( P < 0.005), whereas RV output decreased by 90 ± 18 ml · min−1 · kg−1 atl-NNA10 ( P < 0.02) and by a further 80 ± 22 ml · min−1 · kg−1 atl-NNA25 ( P < 0.05). As a result, RV output exceeded LV output at baseline ( P = 0.03) and l-NNA10 ( P < 0.02) but not at l-NNA25. Fetal body blood flow fell by 95 ± 25 ml · min−1 · kg−1 atl-NNA10 ( P < 0.01), but because placental blood flow decreased by 70 ± 22 ml · min−1 · kg−1 atl-NNA10 ( P < 0.01) and a further 71 ± 21 ml · min−1 · kg−1 atl-NNA25 ( P < 0.01), the fetal body-to-placental blood flow ratio was near unity at baseline andl-NNA10 but rose to 1.5 ± 0.3 atl-NNA25 ( P < 0.05). In association with these flow changes, fetal O2 consumption declined by 1.4 ± 0.3 ml · min−1 · kg−1 atl-NNA10 ( P < 0.05) and by a further 1.5 ± 0.6 ml · min−1 · kg−1 atl-NNA25 ( P < 0.02). These findings suggest that, in midgestation fetal lambs, NO supports an RV flow dominance, whole body O2 utilization, and the maintenance of a near-equal fetoplacental blood flow distribution.

Changes in blood flow distribution during the perinatal period in fetal sheep and lambs

1992 ◽  
Vol 70 (12) ◽  
pp. 1576-1582 ◽  
Author(s):  
Michelle P. Bendeck ◽  
B. Lowell Langille
Keyword(s):  
Blood Flow ◽  
Adrenal Glands ◽  
Flow Distribution ◽  
Perinatal Period ◽  
Tissue Growth ◽  
Late Gestation ◽  
Blood Flow Distribution ◽  
Total Blood ◽  
Fetal Sheep ◽  
Blood Flows

We have measured total blood flows and blood flows per 100 g tissue to major tissues at 120 and 140 days gestation in fetal sheep and at 3 and 21 days of age in lambs (gestation period = 144 ± 2 days). Between 120 and 140 days gestation, flow per 100 g tissue increased by 74, 150, and 317% in the renal, intestinal, and hepatic arterial beds, but no further significant change in flow was observed at 3 or 21 days postpartum. Blood flows per 100 g to cerebral hemispheres and cerebellar tissues also increased dramatically during late gestation (142 and 121%, respectively), but declined sharply by 3 days postpartum (73 and 75%, respectively). Brain blood flows at 21 days postpartum remained substantially below late gestational levels. Adrenal blood flows per 100 g more than doubled during late gestation, fell by more than half at birth, and only partially recovered by 21 days of age. Blood flows to carcass tissues did not change in late gestation, fell at birth, then partially recovered. Pre- and post-natal increases in brain blood flows were almost entirely attributable to increased perfusion rather than tissue growth, whereas large perinatal increases in flow to the diaphragm paralleled tissue growth. Tissue growth and increased perfusion per 100 g contributed almost equally to increased blood flows to kidneys postnatally, and to adrenal glands and the gastrointestinal tract prenatally.Key words: blood flow, perinatal, birth, fetus, sheep.

scholarly journals Blood Flow Distribution during Heat Stress: Cerebral and Systemic Blood Flow

2013 ◽  
Vol 33 (12) ◽  
pp. 1915-1920 ◽  
Author(s):  
Shigehiko Ogoh ◽  
Kohei Sato ◽  
Kazunobu Okazaki ◽  
Tadayoshi Miyamoto ◽  
Ai Hirasawa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Carotid Artery ◽  
Flow Distribution ◽  
Systemic Circulation ◽  
External Carotid Artery ◽  
Whole Body ◽  
External Carotid ◽  
Blood Flows ◽  
Induced Changes

The purpose of the present study was to assess the effect of heat stress-induced changes in systemic circulation on intra- and extracranial blood flows and its distribution. Twelve healthy subjects with a mean age of 22±2 (s.d.) years dressed in a tube-lined suit and rested in a supine position. Cardiac output (Q), internal carotid artery (ICA), external carotid artery (ECA), and vertebral artery (VA) blood flows were measured by ultrasonography before and during whole body heating. Esophageal temperature increased from 37.0±0.2°C to 38.4±0.2°C during whole body heating. Despite an increase in Q (59±31%, P<0.001), ICA and VA decreased to 83±15% ( P=0.001) and 87±8% ( P=0.002), respectively, whereas ECA blood flow gradually increased from 188±72 to 422±189 mL/minute (+135%, P<0.001). These findings indicate that heat stress modified the effect of Q on blood flows at each artery; the increased Q due to heat stress was redistributed to extracranial vascular beds.

Blood flow distribution in tissues of perfused rat hindlimb preparations

1986 ◽  
Vol 250 (4) ◽  
pp. E441-E448 ◽  
Author(s):  
J. Gorski ◽  
D. A. Hood ◽  
R. L. Terjung
Keyword(s):  
Blood Flow ◽  
Large Fraction ◽  
Flow Distribution ◽  
Muscle Performance ◽  
Blood Flow Distribution ◽  
Tissue Mass ◽  
Contracting Muscle ◽  
Trunk Region ◽  
Blood Flows ◽  
Fast Twitch

Aerobic muscle metabolism during concentrations requires adequate blood flow and oxygen delivery. Since the perfused rat hindquarter (HQ) has become widely used for muscle stimulation, we examined the blood flow distribution, using 15 microns radiolabeled microspheres, and oxygen consumption of the HQ, using different commonly used perfusion protocols. Perfusion via the abdominal aorta resulted in well-matched (r = 0.90) blood flows between tissues of both hindlimbs that were proportional to total perfusion inflow. Blood flows to the high-oxidative fast-twitch and slow-twitch red muscle sections were three- to fourfold greater than flows to sections of low-oxidative fast-twitch white muscle. However, a large fraction (28%) of the total inflow went to the trunk region, even though all apparent arterial branches to the trunk region were ligated. This trunk mass accounts for at least 40% of the total metabolic responses of the HQ and diverts a large blood flow that is often presumed to supply the hindlimbs. As a result, muscle performance of the distal hindlimb muscle during stimulation can be inordinately poor. Ligation of the iliac artery to the contralateral limb improves blood flow to the remaining hindlimb but does not eliminate trunk blood flow. In contrast, perfusion via the femoral artery restricted 95% of the inflow to the single hindlimb, thereby reducing the tissue mass perfused. Blood flow to the distal limb musculature was high, resulting in an enhanced muscle performance. Thus single hindlimb perfusion provides a preparation where the contracting muscle is a large fraction of the total tissue, and the venous effluent better reflects the metabolic events in the contracting muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional adrenal blood flow responses to adrenocorticotropic hormone after chronic embolization of the fetal placental circulation in sheep

1996 ◽  
Vol 148 (3) ◽  
pp. 517-522 ◽  
Author(s):  
A M Carter ◽  
J R G Challis ◽  
P Svendsen
Keyword(s):  
Blood Flow ◽  
Adrenal Cortex ◽  
Adrenocorticotropic Hormone ◽  
Maternal Blood ◽  
Arterial Oxygen ◽  
Fetal Sheep ◽  
Cortical Blood Flow ◽  
Arterial Oxygen Content ◽  
Blood Flows ◽  
Placental Blood

Abstract To ascertain whether repeated hypoxic stress would alter the response of the adrenal cortex to adrenocorticotropic hormone (ACTH), by premature activation of the hypothalamic–pituitary–adrenal axis, we studied fetal sheep subjected to daily reduction of arterial oxygen content by embolization of the fetal placental circulation with 15 μm microspheres for 8 days from about day 124 of gestation (term ∼147 days) and sham-embolized controls. Starting before the final embolization (or shamembolization) on day 8, and continuing for 24 h, the fetus was given an intravenous infusion of ACTH1–24 (0·5 μg/h) or vehicle. Fetal and maternal blood samples were taken for determination of immunoreactive cortisol, and regional adrenal and fetal placental blood flows were measured by the microsphere technique at three time points: 1 h before infusion, 3 h after the start of the infusion (1 h after embolization), and after 24 h of infusion. Prior to infusion of ACTH or vehicle, fetal placental blood flow was lower in microsphere-embolized fetuses than in sham-embolized controls (199 ± 15 vs 292 ± 25 ml/min per 100 g tissue; mean ± s.e.; P<0·01). However, plasma cortisol and adrenal cortical blood flow did not differ between embolized fetuses and controls. Adrenal vascular responses to the 24-h infusion of ACTH were similar in embolized and shamembolized fetuses. Adrenal cortical blood flow increased 3-fold (P<0·05) due to decreased vascular resistance (P<0·01), with no change in adrenal medullary blood flow. Thus, while daily embolization of the fetal placental circulation caused a sustained decrease in cotyledonary blood flow, no evidence of altered responsiveness of the adrenal cortex to ACTH was found in these experiments. Journal of Endocrinology (1996) 148, 517–522

Fever and regional blood flows in wethers and parturient ewes

1988 ◽  
Vol 65 (1) ◽  
pp. 165-172 ◽  
Author(s):  
C. M. Blatteis ◽  
J. R. Hales ◽  
A. A. Fawcett ◽  
T. A. Mashburn
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Full Term ◽  
Blood Flows ◽  
Pregnant Sheep ◽  
Regional Blood Flows ◽  
Placental Blood ◽  
Placental Blood Flow

To determine whether the reported absence of fever in full-term-pregnant ewes might be associated with shifts of regional blood flows from thermogenic tissues to placenta during this critical period, fevers were induced twice by injections of Escherichia coli lipopolysaccharide (LPS, 0.25 microgram/kg iv) into each of six Merino ewes from 8 to 1 days prepartum, and their regional blood flow distribution was measured with radioactive, 15-microns-diam microspheres before and during the rise in fever (when their rectal temperature had risen approximately 0.4 degree C). Unexpectedly, fever always developed, rising to heights not significantly different at any time before parturition [4-8 days prepartum = 0.81 +/- 0.23 degree C (SE); 1-3 days prepartum = 0.75 +/- 0.17 degree C) and similar to those in three wethers treated similarly (0.90 +/- 0.10 degree C). Generally, during rising fever, blood flow in the ewes shifted away from heat loss tissues (e.g., skin, nose) to heat production tissues (e.g., shivering muscle, fat) and cardiac output increased; blood flow through redistribution organs (e.g., splanchnic bed) decreased. The reverse occurred during defervescence. Utero-placental blood flow remained high in the febrile ewes. These regional blood flow distributions during febrigenesis and lysis are essentially the same as those during exposures to ambient cold and heat, respectively. Some differences in the responses of cardiac output and its redistribution, however, were apparent between wethers and pregnant ewes. We conclude that 1) the previously reported "absence of fever in the full-term-pregnant sheep" should not be regarded as a general phenomenon and 2) full-term-pregnant sheep support fever production without sacrificing placental blood flow.

Blood flow distribution in dogs during hypothermia and posthypothermia

1978 ◽  
Vol 234 (6) ◽  
pp. H706-H710 ◽  
Author(s):  
T. Anzai ◽  
M. D. Turner ◽  
W. H. Gibson ◽  
W. A. Neely
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Striated Muscle ◽  
Bronchial Artery ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Blood Flows ◽  
Endocrine Organs ◽  
Specific Reactions ◽  
Almost All

Blood flow distribution in tissues of mongrel dogs during hypothermia was studied with radionuclide-tagged microspheres. The animals were cooled at 21 degrees C and rewarmed under thiamylal sodiuni anesthesia. During hypothermia, cardiac output fell to 20% of the control; the highest rate of blood flow relative to normothermic values was observed in the subendocardium of the left ventricle, and the lowest in the hypophysis. Each tissue showed specific reactions to hypothermia. During hypothermia the myocardial and brain-stem blood flows were about 40% of the control; almost all of the digestive tract, striated muscle, adrenal gland, and hypophysis blood flows were maintained at 20% or less of the control. After rewarming, cardiac output recovered to values significantly lower than control. The myocardium, brain, renal cortex, and striated and smooth muscle recovered to control levels; however, blood flow to the digestive organs, bronchial artery flow to the lung, and flow to the endocrine organs did not completely recover by 2 after rewarming.

Oxygen consumption and distribution of blood flow in rats climbing a laddermill

1990 ◽  
Vol 68 (1) ◽  
pp. 241-247 ◽  
Author(s):  
K. I. Norton ◽  
M. T. Jones ◽  
R. B. Armstrong
Keyword(s):  
Blood Flow ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Treadmill Running ◽  
Blood Flow Distribution ◽  
Sprague Dawley ◽  
Circulatory Response ◽  
Blood Flows ◽  
Sprague Dawley Rats

The purpose of this study was threefold: 1) to determine whether untrained rats that refused to run on treadmill would climb on a laddermill (75 degrees incline); 2) to determine O2 consumption (VO2) in untrained rats as a function of laddermill climbing speed; and 3) to determine whether the circulatory response of untrained rats to laddermill climbing is similar to that previously reported for treadmill running at an equivalent VO2. Eighteen female Sprague-Dawley rats that would not perform on a treadmill as part of another study were used to measure VO2 as a function of laddermill speed (5-17 m/min). Data were obtained from all 18 rats; VO2 increased linearly as a function of laddermill speed (r = 0.83, y = 3.0 x + 63.2). Twenty-four female Sprague-Dawley rats that also refused to run on a treadmill were used to measure mean arterial pressure, heart rate, and blood flow distribution (with microspheres) during climbing at 5 and 10 m/min. These exercise intensities were metabolically equivalent to level treadmill running at 45 and 60 m/min (VO2 approximately 78 and 93 ml.min-1.kg-1, respectively). Of the 24 animals, 23 were willing to climb. Mean arterial pressures were higher (approximately 10%) during laddermill climbing than during equivalent treadmill running, but heart rates were the same. General blood flow distribution among muscles as a function of fiber type (with red muscles receiving higher flows) and between muscles and visceral tissues (muscle blood flow increased as a function of exercise intensity while visceral blood flows decreased) were similar to data for rats running on the level.(ABSTRACT TRUNCATED AT 250 WORDS)

Responses to acute hypoxemia in fetal sheep at 0.6-0.7 gestation

1989 ◽  
Vol 256 (3) ◽  
pp. H613-H620 ◽  
Author(s):  
H. S. Iwamoto ◽  
T. Kaufman ◽  
L. C. Keil ◽  
A. M. Rudolph
Keyword(s):  
Blood Flow ◽  
Fetal Sheep ◽  
Blood Flows ◽  
Arterial Blood ◽  
Regulatory Systems ◽  
Group I ◽  
Placental Blood ◽  
Placental Blood Flow ◽  
Sheep Fetus ◽  
I 31

A majority of previous studies of fetal responses to acute hypoxemia has focused on the response of the sheep fetus greater than 120 days of gestation when many regulatory systems have been established. To assess the response of younger, less well-developed fetuses, we exposed two groups of fetal sheep (I, 84-91 days; II, 97-99 days gestational age) to acute hypoxemia by giving the ewe a gas mixture containing 9% O2 to breathe. We decreased descending aortic PO2 in both groups of fetuses [I, 24 +/- 6 to 14 +/- 3 (SD) Torr; II, 23 +/- 3 to 12 +/- 4 Torr] by a degree similar to that achieved in previous studies of fetuses greater than 120 days of gestation. Mean arterial blood pressure (I, 31 +/- 6; II, 40 +/- 3 Torr) did not change significantly from control values, and heart rate (I, 224 +/- 27; II, 203 +/- 16 beats/min) increased significantly in group II fetuses with hypoxemia. In group I and II fetuses, as in older fetuses, cerebral, myocardial, and adrenal blood flows, measured by the microsphere technique, increased, and pulmonary blood flow decreased. These responses mature early and are likely local vascular responses to decreases in oxygen content. Combined ventricular output and umbilical-placental blood flow decreased significantly in both groups. Unlike the response of the fetus greater than 120 days, acute hypoxemia did not decrease blood flow to the musculoskeletal and cutaneous circulations (group I only), gastrointestinal, or renal circulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document