Impaired Skeletal Muscle Microvascular Function and Increased Skeletal Muscle Oxygen Consumption in Severe Falciparum Malaria

Oxygen consumption (VO2) in an isolated, autoperfused, statically exercising canine gracilis muscle (2.5% P0) was studied in low blood flow (Q) states induced by constant norepinephrine (NE) infusion and by mechanical occlusion (MO). Q and VO2 were evaluated at rest (Qc and VO2c), after 5 min of exercise (Qe and VO2e) and after 5 more min of exercise with either NE or MO (Qt and VO2t). Data were normalized and plotted as the VO2e-VO2t)/(VO2c-VO2e) vs. (Qe-Qt)/(Qc-Qe) and equations of the lines for NE (y = 0.090x + 0.048) and for MO (y = 0.488x + 0.070) were determined. The slopes of the lines, tested by analysis of covariance, were significantly different (P less than 0.005). These data indicate that when NE reduced Q during exercise, the exercise induced in VO2 was protected to a greater degree than when MO reduced Q under similar conditions. To determine if the effect of NE on VO2 was secondary to a beta-adrenergic-receptor-mediated of skeletal muscle metabolic processes, the experiments were repeated in the presence of beta-blockade with propranolol. In the presence of beta-blockade, the effects of NE on skeletal muscle VO2 were unchanged. It is therefore hypothesized that the mechanism of this effect of NE may be an increase in the efficiency of oxygen extraction resulting from a redistribution of blood flow to more active muscle fiber regions.

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Increased hemoglobin-oxygen affinity does not decrease skeletal muscle oxygen consumption

Journal of Applied Physiology ◽

10.1152/jappl.1981.51.4.864 ◽

1981 ◽

Vol 51 (4) ◽

pp. 864-870 ◽

Cited By ~ 17

Author(s):

B. K. Ross ◽

M. P. Hlastala

Keyword(s):

Skeletal Muscle ◽

Oxygen Consumption ◽

Oxygen Affinity ◽

Arterial Oxygen ◽

Sodium Metabisulfite ◽

Muscle Oxygen ◽

Hemoglobin Oxygen Affinity ◽

Muscle Oxygen Consumption ◽

Stored Blood ◽

Sodium Cyanate

The importance of hemoglobin-oxygen affinity (HOA) in affecting skeletal muscle oxygen consumption (VO2) was reevaluated using an isolated canine gracilis muscle. HOA of the blood [normal O2 half-saturation pressure of hemoglobin (P50) = 30 Torr] was increased by refrigerated storage (P50 = 22 Torr), incubation in sodium metabisulfite (P50 = 24 Torr), or in sodium cyanate (P50 = 14 Torr). Stored blood caused a significant fall in VO2 to 80% of control, with no change in venous O2 partial pressure (PvO2), substantiating previous studies. However, in contrast, blood incubated in sodium metabisulfite or sodium cyanate resulted in no impairment of VO2, with a fall in PvO2 in the latter case indicating that a critical PvO2 did not cause the reduction in VO2 with stored blood. To substantiate further the lack of existence of a critical PO2, fresh and increased HOA blood was perfused at constant flow rates and varying arterial oxygen saturations. Stored blood showed a marked reduction in VO2 as compared with normal blood over a wide range of saturations. However, carbamylated blood VO2 was identical to fresh blood VO2 values. The data suggest that the position of the oxygen dissociation curve may not be as important as originally thought in determining skeletal muscle oxygen delivery. The drop in VO2 caused by perfusion with stored blood is due to some other factor unrelated to HOA.

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Studies into the determinants of skeletal muscle oxygen consumption: novel insight from near‐infrared diffuse correlation spectroscopy

The Journal of Physiology ◽

10.1113/jp277580 ◽

2019 ◽

Vol 597 (11) ◽

pp. 2887-2901 ◽

Cited By ~ 10

Author(s):

Wesley J. Tucker ◽

Ryan Rosenberry ◽

Darian Trojacek ◽

Houda H. Chamseddine ◽

Carrie A. Arena‐Marshall ◽

...

Keyword(s):

Skeletal Muscle ◽

Oxygen Consumption ◽

Near Infrared ◽

Correlation Spectroscopy ◽

Diffuse Correlation Spectroscopy ◽

Muscle Oxygen ◽

Muscle Oxygen Consumption

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Contribution of BAT and skeletal muscle to thermogenesis induced by ephedrine in man

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1985.248.5.e507 ◽

1985 ◽

Vol 248 (5) ◽

pp. E507-E515 ◽

Cited By ~ 21

Author(s):

A. Astrup ◽

J. Bulow ◽

J. Madsen ◽

N. J. Christensen

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Adipose Tissue ◽

Oxygen Consumption ◽

Local Temperature ◽

Whole Body ◽

Tissue Blood Flow ◽

Muscle Oxygen ◽

Brown Adipose ◽

Muscle Oxygen Consumption

This investigation was performed to examine the role of brown adipose tissue (BAT) in thermogenesis induced by ephedrine in man. Light microscopy of biopsies from necropsy cases showed BAT to occur most frequently in the perirenal fat. Perirenal BAT thermogenesis was investigated in five lean men before and during stimulation with 1 mg ephedrine orally X kg body wt-1. Perirenal BAT thermogenesis was assessed by continuous measurements of local temperature and blood flow with the 133xenon clearance method. In the same study the effect of ephedrine on skeletal muscle oxygen consumption was estimated by measurements of leg blood flow and arteriovenous oxygen difference. The perirenal adipose tissue blood flow increased approximately twofold, whereas the local temperature increased approximately 0.1 degrees C on an average. Assuming that man possesses 700 g of BAT with a similar thermogenic capacity, this tissue contributed only 10 ml X min-1 to the 40 ml X min-1 increase in oxygen consumption in the subject whose perirenal BAT showed the most pronounced response to ephedrine. The leg oxygen consumption increased on an average 60% after ephedrine. By extrapolation of this value to whole body skeletal muscle, approximately 50% of the increase in oxygen consumption induced by ephedrine may take place in skeletal muscle. It is concluded that skeletal muscle is a tissue of importance with respect to the thermogenic effect of sympathomimetics in man, whereas the results do not support a major role for perirenal BAT.

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