The anabolic effect of insulin is dependent on its ability to increase blood flow and muscle perfusion in human subjects

Myocardial blood flow in human subjects was assessed by comparative simultaneous measurement of krypton 85 radioactive decay from coronary sinus and precordial scintillation. Empirical correction of postclearance background from precordial curves yielded a high degree of correlation between flows derived from the two sampling sites (r = .889, P < .001). Comparison of left and right coronary flows in nine subjects revealed similarity in flow through the two vessels over a wide range of actual flow values (r = .945, P < .001).

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Inspiratory resistance delays the reporting of symptoms with central hypovolemia: association with cerebral blood flow

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00087.2007 ◽

2007 ◽

Vol 293 (1) ◽

pp. R243-R250 ◽

Cited By ~ 40

Author(s):

Caroline A. Rickards ◽

Kathy L. Ryan ◽

William H. Cooke ◽

Keith G. Lurie ◽

Victor A. Convertino

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Cerebral Blood Flow Velocity ◽

Lower Body Negative Pressure ◽

Spectral Power ◽

Human Subjects ◽

Low Frequency ◽

Cardiovascular Collapse ◽

Absolute Level ◽

Inspiratory Resistance

We tested the hypothesis that breathing through an inspiratory threshold device (ITD) during progressive central hypovolemia would protect cerebral perfusion and attenuate the reporting of presyncopal symptoms. Eight human subjects were exposed to lower-body negative pressure (LBNP) until the presence of symptoms while breathing through either an active ITD (−7 cmH2O impedance) or a sham ITD (0 cmH2O). Cerebral blood flow velocity (CBFV) was measured continuously via transcranial Doppler and analyzed in both time and frequency domains. Subjects were asked to report any subjective presyncopal symptoms (e.g., dizziness, nausea) at the conclusion of each LBNP exposure. Symptoms were coincident with physiological evidence of cardiovascular collapse (e.g., hypotension, bradycardia). Breathing on the active ITD increased LBNP tolerance time (mean ± SE) from 2,014 ± 106 s to 2,259 ± 138 s ( P = 0.006). We compared CBFV responses at the time of symptoms during the sham ITD trial with those at the same absolute time during the active ITD trial (when there were no symptoms). While there was no difference in mean CBFV at these time points (sham, 44 ± 4 cm/s vs. active, 47 ± 4; P = 0.587), total oscillations (sum of high- and low-frequency spectral power) of CBFV were higher ( P = 0.004) with the active ITD (45.6 ± 10.2 cm/s2) than the sham ITD (22.1 ± 5.4 cm/s2). We conclude that greater oscillations around the same absolute level of mean CBFV are induced by inspiratory resistance and may contribute to the delay in symptoms and cardiovascular collapse that accompany progressive central hypovolemia.

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MECHANISMS OF PERIPHERAL TISSUE BLOOD FLOW INFLUENCED BY HIGH SALT DIET IN YOUNG HEALTHY FEMALE HUMAN SUBJECTS

Journal of Hypertension ◽

10.1097/00004872-201106001-00526 ◽

2011 ◽

Vol 29 ◽

pp. e197

Author(s):

A. Cavka ◽

I. Grizelj ◽

B. Jelakovic ◽

J. H. Lombard ◽

I. Mihaljevic ◽

...

Keyword(s):

Blood Flow ◽

Human Subjects ◽

High Salt ◽

Peripheral Tissue ◽

Tissue Blood Flow ◽

High Salt Diet ◽

Salt Diet ◽

Healthy Female

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Characterization of endothelium-derived hyperpolarizing factor in the human forearm microcirculation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.280.6.h2470 ◽

2001 ◽

Vol 280 (6) ◽

pp. H2470-H2477 ◽

Cited By ~ 65

Author(s):

Julian P. J. Halcox ◽

Suresh Narayanan ◽

Laura Cramer-Joyce ◽

Rita Mincemoyer ◽

Arshed A. Quyyumi

Keyword(s):

Nitric Oxide ◽

Blood Flow ◽

Sodium Nitroprusside ◽

Forearm Blood Flow ◽

Human Subjects ◽

Epoxyeicosatrienoic Acid ◽

Healthy Human ◽

Human Forearm ◽

Oxide Synthase ◽

Cytochrome P 450

The identity of endothelium-dependent hyperpolarizing factor (EDHF) in the human circulation remains controversial. We investigated whether EDHF contributes to endothelium-dependent vasomotion in the forearm microvasculature by studying the effect of K+ and miconazole, an inhibitor of cytochrome P-450, on the response to bradykinin in healthy human subjects. Study drugs were infused intra-arterially, and forearm blood flow was measured using strain-gauge plethysmography. Infusion of KCl (0.33 mmol/min) into the brachial artery caused baseline vasodilation and inhibited the vasodilator response to bradykinin, but not to sodium nitroprusside. Thus the incremental vasodilation induced by bradykinin was reduced from 14.3 ± 2 to 7.1 ± 2 ml · min−1 · 100 g−1( P < 0.001) after KCl infusion. A similar inhibition of the bradykinin ( P = 0.014), but not the sodium nitroprusside (not significant), response was observed with KCl after the study was repeated during preconstriction with phenylephrine to restore resting blood flow to basal values after KCl. Miconazole (0.125 mg/min) did not inhibit endothelium-dependent or -independent responses to ACh and sodium nitroprusside, respectively. However, after inhibition of cyclooxygenase and nitric oxide synthase with aspirin and N G-monomethyl-l-arginine, the forearm blood flow response to bradykinin ( P = 0.003), but not to sodium nitroprusside (not significant), was significantly suppressed by miconazole. Thus nitric oxide- and prostaglandin-independent, bradykinin-mediated forearm vasodilation is suppressed by high intravascular K+ concentrations, indicating a contribution of EDHF. In the human forearm microvasculature, EDHF appears to be a cytochrome P-450 derivative, possibly an epoxyeicosatrienoic acid.

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AN EFFECT OF REDUCED BAROMETRIC PRESSURE ON THE PERIPHERAL CIRCULATION

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o57-091 ◽

1957 ◽

Vol 35 (10) ◽

pp. 777-783

Author(s):

F. Girling ◽

F. A. Sunahara

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Forearm Blood Flow ◽

Human Subjects ◽

Arterial Oxygen Saturation ◽

Barometric Pressure ◽

Peripheral Circulation ◽

Arterial Oxygen ◽

Blood Flows ◽

The Past

Several groups of investigators have noted in the past that exposure to a reduced barometric pressure results in a decrease in peripheral blood flow.In the present study human subjects were exposed to a pressure of 225 mm. Hg with maintenace of arterial oxygen saturation, and forearm and hand blood flows were measured plethysmographically. Forearm blood flow was not affected by the exposure whereas hand blood flow was reduced in all subjects. Blood pressure and heart rate were also measured and showed no change during the experiment.

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Effect of acute normovolemic hemodilution on distribution of blood flow and tissue oxygenation in dog skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.1999.86.3.860 ◽

1999 ◽

Vol 86 (3) ◽

pp. 860-866 ◽

Cited By ~ 39

Author(s):

Jörg Hutter ◽

Oliver Habler ◽

Martin Kleen ◽

Matthias Tiede ◽

Armin Podtschaske ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Oxygen Delivery ◽

Tissue Oxygenation ◽

Relative Dispersion ◽

Homogeneous Distribution ◽

Allogenic Blood Transfusion ◽

Acute Normovolemic Hemodilution ◽

Muscle Perfusion ◽

Normovolemic Hemodilution

Acute normovolemic hemodilution (ANH) is efficient in reducing allogenic blood transfusion needs during elective surgery. Tissue oxygenation is maintained by increased cardiac output and oxygen extraction and, presumably, a more homogeneous tissue perfusion. The aim of this study was to investigate blood flow distribution and oxygenation of skeletal muscle. ANH from hematocrit of 36 ± 3 to 20 ± 1% was performed in 22 splenectomized, anesthetized beagles (17 analyzed) ventilated with room air. Normovolemia was confirmed by measurement of blood volume. Distribution of perfusion within skeletal muscle was determined by using radioactive microspheres. Tissue oxygen partial pressure was assessed with a polarographic platinum surface electrode. Cardiac index (3.69 ± 0.79 vs. 4.79 ± 0.73 l ⋅ min−1 ⋅ m−2) and muscle perfusion (4.07 ± 0.44 vs. 5.18 ± 0.36 ml ⋅ 100 g−1 ⋅ min−1) were increased at hematocrit of 20%. Oxygen delivery to skeletal muscle was reduced to 74% of baseline values (0.64 ± 0.06 vs. 0.48 ± 0.03 ml O2 ⋅ 100 g−1 ⋅ min−1). Nevertheless, tissue [Formula: see text] was preserved (27.4 ± 1.3 vs. 29.9 ± 1.4 Torr). Heterogeneity of muscle perfusion (relative dispersion) was reduced after ANH (20.0 ± 2.2 vs. 13.9 ± 1.5%). We conclude that a more homogeneous distribution of perfusion is one mechanism for the preservation of tissue oxygenation after moderate ANH, despite reduced oxygen delivery.

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Quantification of blood flow patterns in the cerebral arterial circulation of individual (human) subjects

International Journal for Numerical Methods in Biomedical Engineering ◽

10.1002/cnm.3288 ◽

2019 ◽

Vol 36 (1) ◽

Author(s):

Chang S. Park ◽

Grant Hartung ◽

Ali Alaraj ◽

Xinjian Du ◽

Fady T. Charbel ◽

...

Keyword(s):

Blood Flow ◽

Human Subjects ◽

Flow Patterns ◽

Arterial Circulation ◽

Blood Flow Patterns ◽

Individual Human

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Evidence for a dorso-medial parietal system involved in mental transformations of the body

Journal of Neurophysiology ◽

10.1152/jn.1996.76.3.2042 ◽

1996 ◽

Vol 76 (3) ◽

pp. 2042-2048 ◽

Cited By ~ 30

Author(s):

E. Bonda ◽

S. Frey ◽

M. Petrides

Keyword(s):

Blood Flow ◽

Parietal Cortex ◽

Human Subjects ◽

Body Position ◽

The Body ◽

Right Hand ◽

Positron Emission ◽

Superior Parietal Cortex ◽

The Right ◽

Mental Transformations

1. The neural systems underlying body-space mental representation were studied by measuring changes in regional cerebral blood flow (CBF) with positron emission tomography in human subjects. 2. The experimental paradigm involved identification of the left or the right hand of the experimenter presented in different orientations or the palm of the subject's right hand. The subjects were required to decide whether it was the left or the right hand that was presented. To perform this task, the subjects had to move mentally the position of their own arm to adopt that of the experimenter's arm. The control condition involved the same type of tactual stimulation without the requirement of mental transformations of the subject's body position. The distribution of CBF was measured by means of the water bolus H2(15)O methodology during the performance of these tasks. 3. Comparison of the distribution of CBF between the experimental and control tasks was carried out to reveal changes specific to the mental transformations of the subject's body. Significant blood flow increases were observed in the caudal superior parietal cortex, including the intraparietal sulcus, and the adjacent medial parietal cortex. These findings demonstrated that there is a dorsomedially directed parietal system underlying mental transformations of the body in interactive relation with external space.

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Effect of PDE5 inhibition on the modulation of sympathetic α-adrenergic vasoconstriction in contracting skeletal muscle of young and older recreationally active humans

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00653.2015 ◽

2015 ◽

Vol 309 (11) ◽

pp. H1867-H1875 ◽

Cited By ~ 7

Author(s):

Michael Nyberg ◽

Peter Piil ◽

Jon Egelund ◽

Randy S. Sprague ◽

Stefan P. Mortensen ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Human Subjects ◽

Pde5 Inhibitor ◽

Knee Extensor ◽

No Donor ◽

Pde5 Inhibition ◽

Exercise Hyperemia ◽

Functional Sympatholysis ◽

Venous Plasma

Aging is associated with an altered regulation of blood flow to contracting skeletal muscle; however, the precise mechanisms remain unclear. We recently demonstrated that inhibition of cGMP-binding phosphodiesterase 5 (PDE5) increased blood flow to contracting skeletal muscle of older but not young human subjects. Here we examined whether this effect of PDE5 inhibition was related to an improved ability to blunt α-adrenergic vasoconstriction (functional sympatholysis) and/or improved efficacy of local vasodilator pathways. A group of young (23 ± 1 yr) and a group of older (72 ± 1 yr) male subjects performed knee-extensor exercise in a control setting and following intake of the highly selective PDE5 inhibitor sildenafil. During both conditions, exercise was performed without and with arterial tyramine infusion to evoke endogenous norepinephrine release and consequently stimulation of α1- and α2-adrenergic receptors. The level of the sympatholytic compound ATP was measured in venous plasma by use of the microdialysis technique. Sildenafil increased ( P < 0.05) vascular conductance during exercise in the older group, but tyramine infusion reduced ( P < 0.05) this effect by 38 ± 9%. Similarly, tyramine reduced ( P < 0.05) the vasodilation induced by arterial infusion of a nitric oxide (NO) donor by 54 ± 9% in the older group, and this effect was not altered by sildenafil. Venous plasma [ATP] did not change with PDE5 inhibition in the older subjects during exercise. Collectively, PDE5 inhibition in older humans was not associated with an improved ability for functional sympatholysis. An improved efficacy of the NO system may be one mechanism underlying the effect of PDE5 inhibition on exercise hyperemia in aging.

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