Relationship of changes in diaphragmatic muscle blood flow to muscle contractile activity

1987 ◽  
Vol 62 (1) ◽  
pp. 291-299 ◽  
Author(s):  
H. Bark ◽  
G. S. Supinski ◽  
J. C. Lamanna ◽  
S. G. Kelsen
Keyword(s):  
Blood Flow ◽  
Duty Cycle ◽  
Contractile Activity ◽  
Muscle Blood Flow ◽  
Muscle Tension ◽  
Mechanically Ventilated ◽  
Diaphragmatic Muscle ◽  
Tension Time ◽  
Relationship Of ◽  
Muscle Contractile

The effect of increases in diaphragmatic muscle contractile activity on diaphragm blood flow remains unclear. The present study examined the effect of electrically induced isometric diaphragmatic muscle contractions on diaphragmatic blood flow. Studies were performed on diaphragmatic muscle strips prepared in anesthetized mechanically ventilated dogs. Diaphragmatic contractile activity was quantitated as the tension-time index (TTI) (i.e., the product of tension magnitude and duration). Blood flow to the strip (Qdi) was measured from the volume of the phrenic venous effluent using a drop counter. The separate effects on Qdi of 30-s periods of continuous and rhythmic contractions were examined. Qdi increased with increases in TTI and peaked at a TTI of 20–30% of maximum after which Qdi fell progressively with further increases in TTI. At levels of TTI greater than 30%, the pattern of muscle contraction significantly affected blood flow. Qdi was significantly lower during activity and the postcontraction hyperemia significantly greater at a given TTI when contractions were continuous than when contractions were intermittent. Above a TTI of 30%, Qdi during contraction decreased linearly with increases in duty cycle and curvilinearly with increases in tension. We conclude that during isometric diaphragmatic contractions, diaphragmatic blood flow may become mechanically impeded, and the magnitude of the impediment in blood flow depends on the pattern of diaphragmatic contractions. With increases in contractile activity above a critical level, changes in duty cycle exert progressively greater effects on diaphragmatic blood flow than changes in muscle tension.

Relation of blood flow to VO2, PO2, and PCO2 in dog gastrocnemius muscle

1988 ◽  
Vol 255 (5) ◽  
pp. H1004-H1010 ◽  
Author(s):  
D. E. Mohrman ◽  
R. R. Regal
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Gastrocnemius Muscle ◽  
Muscle Blood Flow ◽  
Carbon Dioxide Tension ◽  
Experimental Conditions ◽  
Muscle Oxygen ◽  
Muscle Oxygen Consumption ◽  
Relationship Of ◽  
The Relationship

We pump-perfused gastrocnemius-plantaris muscle preparations at constant pressure to study the relationship of muscle blood flow (Q) to muscle oxygen consumption (VO2), venous oxygen tension (PVO2), and venous carbon dioxide tension (PVCO2) during steady-state exercise at different rates. Tests were performed under four experimental conditions produced by altering the perfusate blood-gas status with a membrane lung. The consistency of the relationship of Q to other variables was evaluated by statistical analysis of fitted curves. Not one of the above listed variables had the same relationship with Q in all four of the experimental conditions we tested. However, we did find that a consistent relationship existed among Q, PVO2, and PVCO2 in our data. That relationship is well described by the equation (Q-23).[PVO2 - (0.5.PVCO2) - 3] = 105 (when Q is expressed in ml.100 g-1.min-1 and PVO2 and PVCO2 in mmHg). One interpretation of this result is that both PO2 and PCO2 are important variables in the control of blood flow in skeletal muscle the combined influence of which could account for nearly all of the hyperemia response to steady-state muscle exercise.

Diaphragmatic blood flow in the dog

1986 ◽  
Vol 60 (2) ◽  
pp. 554-561 ◽  
Author(s):  
H. Bark ◽  
S. M. Scharf
Keyword(s):  
Blood Flow ◽  
Duty Cycle ◽  
Stimulus Frequency ◽  
Phase Flow ◽  
Transdiaphragmatic Pressure ◽  
Relaxation Phase ◽  
Duty Cycles ◽  
Tension Time ◽  
Phrenic Artery ◽  
Electromagnetic Flow Probe

In anesthetized mongrel dogs we measured the blood flow in the left phrenic artery (Qdi), using an electromagnetic flow probe, before and during supramaximal phrenic nerve stimulation (pacing). This was done at constant respiratory rate (24/min) but at three different stimulation frequencies at a duty cycle of 0.4 (20, 50, and 100 Hz) and at three different duty cycles at a stimulation frequency of 50 Hz (duty cycle = 0.2, 0.4, and 0.8). Qdi was unchanged during diaphragm contraction until transdiaphragmatic pressure (Pdi) was greater than approximately 11 cmH2O, whereafter it began to decrease, reaching zero at Pdi approximately 20 cmH2O. Thus, when Pdi was greater than 21 cmH2O, all flow occurred during relaxation. Qdi averaged over the entire respiratory cycle (Qt) was less at duty cycle = 0.8 than under the other conditions. This was because of decreasing length of relaxation phase rather than a difference of relaxation phase flow (Qr), which was maximal during all conditions of phrenic stimulation. During pacing-induced fatigue, Qt actually rose slightly as Pdi fell. This was due to an increase in contraction phase flow while Qr remained constant. The relationship between Qt and tension-time index was not unique but varied according to the different combinations of duty cycle and stimulus frequency.

Effects of contraction frequency and duty cycle on diaphragmatic blood flow

1985 ◽  
Vol 58 (1) ◽  
pp. 265-273 ◽  
Author(s):  
B. Buchler ◽  
S. Magder ◽  
C. Roussos
Keyword(s):  
Blood Flow ◽  
Duty Cycle ◽  
Contraction Time ◽  
Phrenic Nerve Stimulation ◽  
Contraction Frequency ◽  
Time Index ◽  
High Duty Cycle ◽  
Duty Cycles ◽  
Tension Time ◽  
Microsphere Method

The effects of diaphragmatic contraction frequency (no. of intermittent tetanic contractions/min) at a given tension-time index and of duty cycle (contraction time/total cycle time) on diaphragmatic blood flow were measured in anesthetized mongrel dogs during bilateral supramaximal phrenic nerve stimulation. Diaphragmatic blood flow was measured by the radionuclide-labeled microsphere method. Contraction frequency was varied between 10 and 160/min at duty cycles of 0.25 and 0.75. Diaphragmatic blood flow increased with contraction frequency from 1.47 +/- 0.13 ml X min-1 X g-1 (mean +/- SE) at an average of 18/min to 2.65 +/- 0.16 ml X min-1 X g-1 at 74/min (P less than 0.01) with a duty cycle of 0.25 and from 1.32 +/- 0.19 ml X min-1 X g-1 at an average of 15/min to 1.96 +/- 0.15 ml X min-1 X g-1 at 80/min (P less than 0.02) with a duty cycle of 0.75. At higher contraction frequencies diaphragmatic blood flow did not increase further at both duty cycles. In addition, diaphragmatic blood flow was higher with a duty cycle of 0.25 than 0.75 at all contraction frequencies. We conclude that frequency of contraction is a major determinant of diaphragmatic blood flow and that high duty cycle impedes diaphragmatic blood flow.

Effect of amrinone on diaphragm blood flow

1988 ◽  
Vol 65 (4) ◽  
pp. 1506-1513 ◽  
Author(s):  
R. J. Bundy ◽  
J. S. Arnold ◽  
A. F. DiMarco ◽  
F. Hussein ◽  
G. S. Supinski
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Isometric Force ◽  
Vena Cava ◽  
Force Transducer ◽  
Mechanically Ventilated ◽  
Before And After ◽  
Tension Time ◽  
Vascular Beds

The purpose of the present study was to examine the effect of amrinone, a drug known to augment cardiac output and dilate peripheral vascular beds, on diaphragm blood flow. Studies were performed on 12 anesthetized mechanically ventilated dogs in which strips of left costal diaphragm were developed in situ. Strip blood flow was assessed with a drop counter attached to a catheter tied into the phrenic veins' draining strips. Strip tension was measured with an isometric force transducer. Amrinone was administered as an intravenous bolus of 2 mg/kg followed by a continuous infusion of 25 micrograms.kg-1.min-1. Amrinone increased cardiac output and resting diaphragm blood flow [from 1.8 +/- 0.1 to 3.2 +/- 3 (SE) l/min and from 13 +/- 2 to 29 +/- 6 (SE) ml.100 g-1.min-1, respectively, P less than 0.001 for both comparisons]. Amrinone also increased blood flow during periods of rhythmic contraction (tension time indexes of 0.1-0.4, P less than 0.05 for comparisons of flow with and without amrinone at each tension time index) and increased the magnitude of the postcontraction hyperemia (P less than 0.02 for comparisons of hyperemic flow with and without amrinone at tension time indexes of 0.3 and 0.4). Graded occlusion of the inferior vena cava produced reductions in arterial pressure, cardiac output, and diaphragm blood flow both before and after amrinone. Both cardiac output and diaphragm blood flow were greater after amrinone, however, at all levels of blood pressure examined. These findings indicate that amrinone can override diaphragm vasoregulatory systems and augment diaphragm blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvascular development during normal growth and reduced blood flow: introduction of a new model

1991 ◽  
Vol 260 (6) ◽  
pp. H1966-H1972 ◽  
Author(s):  
D. H. Wang ◽  
R. L. Prewitt
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Blood Flow ◽  
Muscle Tension ◽  
Normal Growth ◽  
Total Blood ◽  
Tissue Mass ◽  
Cross Sectional ◽  
Intact Muscle ◽  
Total Blood Flow

The purpose of this study was to evaluate microvascular development during normal skeletal muscle maturation and to determine the alterations associated with decreased blood flow caused by a decrease in demand. Unilateral orchidectomy was performed on 4-wk-old rats to reduce muscle tension and growth of one cremaster muscle. Three weeks later, total blood flow was reduced to 58 +/- 9% measured by the dual-slit velocity technique and 55 +/- 9% by radioactive microspheres, and the muscle was smaller when compared with the intact contralateral muscle. Blood flow per gram of tissue was not significantly different. Measured by closed-circuit television microscopy, the internal diameters and wall cross-sectional areas of all orders of arterioles (1A-4A), and the number of 4As per 3A had increased with age in the control muscle. The arcading arterioles increased in length by 35% as the intact muscle grew, but the number of 3As remained unchanged. Arteriolar length increased but not in proportion to muscle mass. As a result, large and small arteriolar density decreased with age. Thus, during normal skeletal muscle maturation, preexisting arterioles became elongated and only precapillary arterioles increased in number, resulting in a decreased ratio of arteriolar number to tissue mass. Unilateral orchidectomy inhibited the growth of arterioles in both size and number. A reduced diameter of the 1A in the orchidectomy muscle resulted in unchanged wall shear rate. Flow-induced shear stress and/or local changes in growth factors are suggested as possible mechanisms mediating the alterations.

Effect of contraction frequency on leg blood flow during knee extension exercise in humans

2001 ◽  
Vol 91 (2) ◽  
pp. 671-679 ◽  
Author(s):  
Brian D. Hoelting ◽  
Barry W. Scheuermann ◽  
Thomas J. Barstow
Keyword(s):  
Blood Flow ◽  
Doppler Ultrasound ◽  
Femoral Artery ◽  
Supine Position ◽  
Muscle Blood Flow ◽  
Muscle Tension ◽  
Knee Extension ◽  
Contraction Frequency ◽  
Knee Extension Exercise ◽  
Exercise In Humans

Previous studies in isolated muscle preparations have shown that muscle blood flow becomes compromised at higher contraction frequencies. The purpose of this study was to examine the effect of increases in contraction frequency and muscle tension on mean blood flow (MBF) during voluntary exercise in humans. Nine male subjects [23.6 ± 3.7 (SD) yr] performed incremental knee extension exercise to exhaustion in the supine position at three contraction frequencies [40, 60, and 80 contractions/min (cpm)]. Mean blood velocity of the femoral artery was determined beat by beat using Doppler ultrasound. MBF was calculated by using the diameter of the femoral artery determined at rest using echo Doppler ultrasound. The work rate (WR) achieved at exhaustion was decreased ( P< 0.05) as contraction frequency increased (40 cpm, 16.2 ± 1.4 W; 60 cpm, 14.8 ± 1.4 W; 80 cpm, 13.2 ± 1.3 W). MBF was similar across the contraction frequencies at rest and during the first WR stage but was higher ( P < 0.05) at 40 than 80 cpm at exercise intensities >5 W. MBF was similar among contraction frequencies at exhaustion. In humans performing knee extension exercise in the supine position, muscle contraction frequency and/or muscle tension development may appreciably affect both the MBF and the amplitude of the contraction-to-contraction oscillations in muscle blood flow.

scholarly journals Fatigability and blood flow in the rat gastrocnemius-plantaris-soleus after hindlimb suspension

1992 ◽  
Vol 73 (3) ◽  
pp. 1135-1140 ◽  
Author(s):  
K. S. McDonald ◽  
M. D. Delp ◽  
R. H. Fitts
Keyword(s):  
Blood Flow ◽  
Contractile Activity ◽  
Muscle Blood Flow ◽  
Muscle Group ◽  
Stimulation Frequency ◽  
Hindlimb Suspension ◽  
Cage Control

The purpose of this study was to test the hypothesis that hindlimb suspension increases the fatigability of the soleus during intense contractile activity and determine whether the increased fatigue is associated with a reduced muscle blood flow. Cage-control (C) and 15-day hindlimb-suspended (HS) rats were anesthetized, and either the gastrocnemius-plantaris-soleus (G-P-S) muscle group or the soleus was stimulated (100 Hz, 100-ms trains at 120/min) for 10 min in situ. In the G-P-S preparation, blood flow was measured with radiolabeled microspheres before and at 2 and 10 min of contractile activity. The G-P-S fatigued markedly at this stimulation frequency, and the differences between C and HS animals were not significant until the 9th min of contractile activity. In contrast, the stimulation resulted in faster rates and significantly larger amounts of fatigue in the soleus from HS than from C animals. The atrophied soleus showed significant differences by 1 min of stimulation (C = 70 +/- 1% vs. HS = 57 +/- 2% of peak train force) and remained different at 10 min (C = 64 +/- 4% vs. HS = 45 +/- 2% peak train force). Relative blood flow to the soleus was similar between groups before and during contractile activity (rest: C = 20 +/- 3 vs. HS = 12 +/- 3; 2 min: C = 128 +/- 6 vs. HS = 118 +/- 4; 10 min: C = 123 +/- 11 vs. HS = 105 +/- 11 ml.min-1.100 g-1). In conclusion, these results established that 15 days of HS increased the fatigability of the soleus, but the effect was not caused by a reduced muscle blood flow.

Effect of contraction frequency on the contractile and noncontractile phases of muscle venous blood flow

2003 ◽  
Vol 95 (3) ◽  
pp. 1139-1144 ◽  
Author(s):  
Michael C. Hogan ◽  
Bruno Grassi ◽  
Michele Samaja ◽  
Creed M. Stary ◽  
L. B. Gladden
Keyword(s):  
Blood Flow ◽  
Metabolic Rate ◽  
Duty Cycle ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Contraction Frequency ◽  
Time Integral ◽  
Tension Time ◽  
Percent Contribution ◽  
Rhythmic Contractions

The purpose of this study was to test the hypothesis that increasing muscle contraction frequency, which alters the duty cycle and metabolic rate, would increase the contribution of the contractile phase to mean venous blood flow in isolated skeletal muscle during rhythmic contractions. Canine gastrocnemius muscle ( n = 5) was isolated, and 3-min stimulation periods of isometric, tetanic contractions were elicited sequentially at rates of 0.25, 0.33, and 0.5 contractions/s. The O2 uptake, tension-time integral, and mean venous blood flow increased significantly ( P < 0.05) with each contraction frequency. Venous blood flow during both the contractile (106 ± 6, 139 ± 8, and 145 ± 8 ml·100 g-1·min-1) and noncontractile phases (64 ± 3, 78 ± 4, and 91 ± 5 ml·100 g-1·min-1) increased with contraction frequency. Although developed force and duration of the contractile phase were never significantly different for a single contraction during the three contraction frequencies, the amount of blood expelled from the muscle during an individual contraction increased significantly with contraction frequency (0.24 ± 0.03, 0.32 ± 0.02, and 0.36 ± 0.03 ml·N-1·min-1, respectively). This increased blood expulsion per contraction, coupled with the decreased time in the noncontractile phase as contraction frequency increased, resulted in the contractile phase contribution to mean venous blood flow becoming significantly greater (21 ± 4, 30 ± 4, and 38 ± 6%) as contraction frequency increased. These results demonstrate that the percent contribution of the muscle contractile phase to mean venous blood flow becomes significantly greater as contraction frequency (and thereby duty cycle and metabolic rate) increases and that this is in part due to increased blood expulsion per contraction.

scholarly journals Effect of hindlimb unweighting on tissue blood flow in the rat

1992 ◽  
Vol 72 (6) ◽  
pp. 2210-2218 ◽  
Author(s):  
K. S. McDonald ◽  
M. D. Delp ◽  
R. H. Fitts
Keyword(s):  
Blood Flow ◽  
Soleus Muscle ◽  
Contractile Activity ◽  
Muscle Blood Flow ◽  
Treadmill Running ◽  
Tissue Blood Flow ◽  
Hindlimb Unweighting ◽  
Visceral Organs ◽  
Apparent Reduction ◽  
Fast Twitch

The purpose of this study was to characterize the distribution of blood flow in the rat during hindlimb unweighting (HU) and post-HU standing and exercise and examine whether the previously reported (Witzmann et al., J. Appl. Physiol. 54: 1242–1248, 1983) elevation in anaerobic metabolism observed with contractile activity in the atrophied soleus muscle was caused by a reduced hindlimb blood flow. After either 15 days of HU or cage control, blood flow was measured with radioactive microspheres during unweighting, normal standing, and running on a treadmill (15 m/min). In another group of control and experimental animals, blood flow was measured during preexercise (PE) treadmill standing and treadmill running (15 m/min). Soleus muscle blood flow was not different between groups during unweighting, PE standing, and running at 15 m/min. Chronic unweighting resulted in the tendency for greater blood flow to muscles composed of predominantly fast-twitch glycolytic fibers. With exercise, blood flow to visceral organs was reduced compared with PE values in the control rats, whereas flow to visceral organs in 15-day HU animals was unaltered by exercise. These higher flows to the viscera and to muscles composed of predominantly fast-twitch glycolytic fibers suggest an apparent reduction in the ability of the sympathetic nervous system to distribute cardiac output after chronic HU. In conclusion, because 15 days of HU did not affect blood flow to the soleus during exercise, the increased dependence of the atrophied soleus on anerobic energy production during contractile activity cannot be explained by a reduced muscle blood flow.

Influence of training following bilateral stenosis of the femoral artery in rats

1986 ◽  
Vol 250 (6) ◽  
pp. H1050-H1059 ◽  
Author(s):  
G. M. Mathien ◽  
R. L. Terjung
Keyword(s):  
Blood Flow ◽  
Exercise Tolerance ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Muscle Tension ◽  
Muscle Performance ◽  
Dramatic Improvement ◽  
Hindlimb Muscle

The influence of training on muscle performance in situ, exercise tolerance in vivo, and muscle blood flow, was assessed in rats in which femoral arteries were previously surgically constricted to severely limit active hyperemia but not to restrict normal resting blood flow (BF). Muscle BF to the different fiber type sections of the gastrocnemius plantaris soleus muscle group was determined during in situ stimulation (15 and 30 tetani/min) using 15-microns microspheres after 0, 1, 2, 3, and 5 wk (n = 5-6/wk) of daily treadmill training. Surgical stenosis was performed 48 h prior to the initiation of training. The ability of the hindlimb muscle of sedentary stenosed animals to maintain tension in situ improved from an extensive deficit to normal at 3 wk during relatively mild contractions (15 tetani/min) but not at 5 wk during 30 tetani/min. Although BF improved to normal at 15 tetani/min, a large BF deficit remained at 30 tetani/min. Exercise tolerance during running increased approximately twofold in duration. In contrast, trained stenosed animals demonstrated normal muscle tension in situ by 2 wk during 15 tetani/min and at 5 wk during 30 tetani/min. Exercise tolerance during running increased in duration (approximately fivefold) and intensity (approximately twofold). Although BF to the entire contracting muscle mass was not different between trained and sedentary stenosed animals, its distribution within the gastrocnemius was more homogenous (P less than 0.001). This was probably due to adaptations within the fast-twitch white muscle section and could have contributed to the dramatic improvement in muscle function and exercise tolerance exhibited by the trained stenosed animals.

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