Muscle chemoreflex alters vascular conductance in nonischemic exercising skeletal muscle

Previous studies have shown that the muscle chemoreflex causes an augmented blood pressure response to exercise and partially restores blood flow to ischemic muscle. The purpose of this study was to investigate the effects of the muscle chemoreflex on blood flow to nonischemic exercising skeletal muscle. During each experiment, dogs ran at 10 kph for 8–16 min and the muscle chemoreflex was evoked by reducing hindlimb blood flow at 4-min intervals (0–80%). Arterial blood pressure, hindlimb blood flow, forelimb blood flow, and forelimb vascular conductance were averaged over the last minute at each level of occlusion. Stimulation of the muscle chemoreflex caused increases in arterial blood pressure and forelimb blood flow and decreases in forelimb vascular conductance. The decrease in forelimb vascular conductance demonstrates that the muscle chemoreflex causes vasoconstriction in the nonischemic exercising forelimb. Despite the decrease in vascular conductance, the increased driving pressure caused by the pressor response was large enough to produce an increased forelimb blood flow.

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Effect of the Ace Inhibitor Ceronapril on Cerebral Blood flow in Hypertensive Patients

Annals of Pharmacotherapy ◽

10.1177/106002809603000601 ◽

1996 ◽

Vol 30 (6) ◽

pp. 578-582 ◽

Cited By ~ 5

Author(s):

Neal R Cutler ◽

John J Sramek ◽

Azucena Luna ◽

Ismael Mena ◽

Eric P Brass ◽

...

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Diastolic Blood Pressure ◽

Arterial Blood Pressure ◽

Mean Arterial Blood Pressure ◽

Enzyme Inhibitor ◽

Blood Pressure Response ◽

Combined Therapy ◽

Arterial Blood

Objective To assess the effect of the angiotensin-converting enzyme inhibitor ceronapril on cerebral blood flow (CBF) in patients with moderate hypertension. Design Patients received chlorthalidone 25 mg for 4 weeks, and if diastolic blood pressure remained in the range of 100–115 mm Hg, they were given titrated doses of ceronapril (10–40 mg/d based on blood pressure response) in addition to chlorthalidone for 9 weeks. Setting Outpatient research clinic. Subjects Eligible patients had moderate essential hypertension (diastolic blood pressure 100–115 mm Hg) assessed when the patients were receiving no medications. Thirteen patients were entered into the study; 1 withdrew for reasons unrelated to the study drug. Twelve patients (11 men, 1 woman; mean age 52 y) completed the study. Intervention Ceronapril, given with chlorthalidone. Main Outcome Measures CBF measurements were taken at the start and end of ceronapril therapy using intravenous 133Xe; blood pressures were determined weekly. Results Mean arterial blood pressure decreased from 130 ± 4 to 120 ±7 mm Hg after 4 weeks of chlorthalidone administration, and fell further to 108 ± 8 mm Hg after an additional 9 weeks of combined chlorthalidone-ceronapril therapy (p < 0.05). CBF fell from 44 ± 15 to 34 ± 5 mL/min/100 g during the 9 weeks of combined therapy (p = 0.05). No adverse effects consistent with decreased CBF were observed. The decrease in CBF was not linearly correlated with the change in systemic blood pressure, but was strongly correlated (r = –0.937; p < 0.001) with the initial CBF. Conclusions The decrease in mean arterial blood pressure was not associated with a decrease in CBF. Patients with high CBF may be predisposed to a decrease in CBF when treated with ceronapril and chlorthalidone.

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Effect of vasopressors on organ blood flow during endotoxin shock in pigs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.252.2.h291 ◽

1987 ◽

Vol 252 (2) ◽

pp. H291-H300 ◽

Cited By ~ 7

Author(s):

M. J. Breslow ◽

C. F. Miller ◽

S. D. Parker ◽

A. T. Walman ◽

R. J. Traystman

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Blood Flow ◽

Left Ventricle ◽

Arterial Blood Pressure ◽

Endotoxin Shock ◽

Organ Blood Flow ◽

Shock Model ◽

Blood Pressure Elevation ◽

Arterial Blood

A volume-resuscitated porcine endotoxin shock model was used to evaluate the effect on organ blood flow of increasing systemic arterial blood pressure with vasopressors. Administration of 0.05–0.2 mg/kg of Escherichia coli endotoxin (E) reduced mean arterial blood pressure (MAP) to 50 mmHg, decreased systemic vascular resistance to 50% of control, and did not change cardiac output or heart rate. Blood flow to brain, kidney, spleen, and skeletal muscle was reduced during endotoxin shock, but blood flow to left ventricle, small and large intestine, and stomach remained at pre-endotoxin levels throughout the study period. Four groups of animals were used to evaluate the effect of vasopressor therapy. A control group received E and no vasopressor, whereas the other three groups received either norepinephrine, dopamine, or phenylephrine. Vasopressors were administered starting 60 min after E exposure, and the dose of each was titrated to increase MAP to 75 mmHg. Despite the increase in MAP, brain blood flow did not increase in any group. Norepinephrine alone increased blood flow to the left ventricle. Kidney, splanchnic, and skeletal muscle blood flow did not change with vasopressor administration. The dose of norepinephrine required to increase MAP by 20–25 mmHg during E shock was 30 times the dose required for a similar increase in MAP in animals not receiving E. We conclude that hypotension in the fluid resuscitated porcine E shock model is primarily the result of peripheral vasodilatation, that the vascular response to vasoconstrictors in this model is markedly attenuated following E administration, that blood pressure elevation with norepinephrine, dopamine, and phenylephrine neither decreases blood flow to any organ nor increases blood flow to organs with reduced flow, and that norepinephrine, dopamine, and phenylephrine affect regional blood flow similarly in this model.

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Muscle chemoreflex causes renal vascular constriction

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1996.270.3.h951 ◽

1996 ◽

Vol 270 (3) ◽

pp. H951-H956 ◽

Cited By ~ 20

Author(s):

S. W. Mittelstadt ◽

L. B. Bell ◽

K. P. O'Hagan ◽

J. E. Sulentic ◽

P. S. Clifford

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Sympathetic Nerve Activity ◽

Vascular Conductance ◽

Renal Sympathetic Nerve Activity ◽

Arterial Blood ◽

Significant Difference ◽

Renal Vascular ◽

Muscle Chemoreflex ◽

Renal Sympathetic

The purpose of this study was to investigate the effects of the muscle chemoreflex on vascular conductance in innervated and denervated kidneys. During each experiment, six dogs ran at 10 km/h for 8-16 min, and the muscle chemoreflex was stimulated by reducing hindlimb blood flow (HLBF) (0%-74%) at 4-min intervals. Small reductions in HLBF did not cause changes in arterial blood pressure or renal vascular conductance. However, further reductions of HLBF caused increases in arterial blood pressure and decreases in renal vascular conductance. Decreases in renal vascular conductance occurred in the denervated kidneys when the HLBF was reduced below 1,500 +/- 215 ml/min and occurred in the innervated kidneys when HLBF was reduced below 1,402 +/- 161 ml/min. There was not a significant difference between the reductions in HLBF required to cause a decrease in vascular conductance in the innervated and denervated kidneys. These results demonstrate that reductions in HLBF cause decreases in renal vascular conductance, which are not dependent on renal sympathetic nerve activity.

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Neural control of muscle blood flow during exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00076.2004 ◽

2004 ◽

Vol 97 (2) ◽

pp. 731-738 ◽

Cited By ~ 146

Author(s):

Gail D. Thomas ◽

Steven S. Segal

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Blood Flow ◽

Arterial Blood Pressure ◽

Sympathetic Nerve ◽

Neural Control ◽

Sympathetic Nerve Activity ◽

Muscle Blood Flow ◽

Nerve Activity ◽

Arterial Blood

Activation of skeletal muscle fibers by somatic nerves results in vasodilation and functional hyperemia. Sympathetic nerve activity is integral to vasoconstriction and the maintenance of arterial blood pressure. Thus the interaction between somatic and sympathetic neuroeffector pathways underlies blood flow control to skeletal muscle during exercise. Muscle blood flow increases in proportion to the intensity of activity despite concomitant increases in sympathetic neural discharge to the active muscles, indicating a reduced responsiveness to sympathetic activation. However, increased sympathetic nerve activity can restrict blood flow to active muscles to maintain arterial blood pressure. In this brief review, we highlight recent advances in our understanding of the neural control of the circulation in exercising muscle by focusing on two main topics: 1) the role of motor unit recruitment and muscle fiber activation in generating vasodilator signals and 2) the nature of interaction between sympathetic vasoconstriction and functional vasodilation that occurs throughout the resistance network. Understanding how these control systems interact to govern muscle blood flow during exercise leads to a clear set of specific aims for future research.

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The Effect of Vibration on Blood Flow in Skeletal Muscle in the Rabbit

Clinical Science ◽

10.1042/cs0550471 ◽

1978 ◽

Vol 55 (5) ◽

pp. 471-476 ◽

Cited By ~ 1

Author(s):

O. Hudlická ◽

A. Wright

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Blood Flow ◽

Arterial Blood Pressure ◽

Perfusion Pressure ◽

Venous Pressure ◽

Arterial Blood ◽

Resistance Vessels ◽

Denervated Muscles ◽

Initial Blood

1. The blood flow in rabbit gastrocnemius, as measured by photoelectric drop-counter, increased when the muscle was vibrated at frequencies of 22–62 Hz. 2. Blood flow increased rapidly within 1–2 s of the start of vibration, and lasted for the whole time vibration was applied. 3. The increase in blood flow was negatively correlated with the initial blood flow, being greater with lower flows. 4. The magnitude of increase was similar in both innervated and acutely denervated muscles. 5. The arterial blood pressure did not change apart from a very brief fall at the beginning of vibration. Venous pressure rose and, consequently, the perfusion pressure was lower. The increase in blood flow thus indicates a considerable dilatation in the resistance vessels of skeletal muscle.

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Blood pressure response to exercise in young athletes aged 10 to 18 years

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2015-0101 ◽

2016 ◽

Vol 41 (1) ◽

pp. 41-48 ◽

Cited By ~ 2

Author(s):

Katarzyna Szmigielska ◽

Anna Szmigielska-Kapłon ◽

Anna Jegier

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Exercise Test ◽

Blood Pressure Response ◽

Pressure Response ◽

Multivariate Linear Regression Analysis ◽

Young Athletes ◽

Arterial Blood ◽

Systolic Arterial Blood Pressure ◽

Response To Exercise

The aim of the study was to determine arterial blood pressure response to exercise in young athletes. The study group comprised 711 young athletes (457 boys, 254 girls) aged 10 to 18 years (mean 13.41 ± 3.12 years) who had been training for an average of 7.62 ± 4.2 h per week for an average of 4.01 ± 2.5 years. Participants with elevated arterial blood pressure above the 90th percentile at rest were excluded from investigation. A symptom-limited, multistage exercise test to exhaustion was performed using a Monark cycle ergometer. Arterial blood pressure was measured with an aneroid manometer in the third minute of each stage of the test. Mean systolic arterial blood pressure during peak exercise was significantly higher in boys than in girls: 183.21 ± 27.97 mm Hg and 170.97 ± 21.4 mm Hg, respectively (p = 0.03). Multivariate linear regression analysis showed that age and workload had significant effects on arterial blood pressure during the test. Systolic arterial blood pressure during the exercise can be described with the following equations: boys, SBPex (mm Hg) = –1.92 × age (years) + 0.55 × workload (W) + 120.84; girls, SBPex (mm Hg) = –0.88 × age (years) + 0.48 × workload (W) + 111.22. The study results describe reference values of arterial blood pressure during the exercise test. The presented equations and figures can help to assess whether the arterial blood pressure at each stage of the exercise test exceeds the normal range or not.

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Direct oxymetric peripheral tissue perfusion monitoring during open heart surgery with the use of cardiopulmonary bypass: preliminary experience

Perfusion ◽

10.1177/0267659111419272 ◽

2011 ◽

Vol 26 (6) ◽

pp. 510-515 ◽

Cited By ~ 2

Author(s):

V Lonsky ◽

V Svitek ◽

V Brzek ◽

J Kubicek ◽

M Volt ◽

...

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Blood Flow ◽

Cardiopulmonary Bypass ◽

Arterial Blood Pressure ◽

Oxygen Tension ◽

Mean Arterial Blood Pressure ◽

Tissue Perfusion ◽

Deltoid Muscle ◽

Arterial Blood

Background: Regional hypoperfusion has been associated with the development of postoperative organ dysfunction in cardiac surgery involving cardiopulmonary bypass (CPB). Direct tissue oxymetry is a potentially new method for monitoring the quality of the peripheral tissue perfusion during CPB. The aim of this study was to assess the effects of CPB in skeletal muscle oxygenation when measured in the deltoid muscle by direct oxymetry during perioperative period. Method: Seven patients underwent on-pump coronary artery bypass grafting. Direct oxymetry was performed by an optical cathether introduced into the deltoid muscle. Continuous measurement was made during the surgical procedure and the postoperative period. Mean arterial blood pressure, blood flow during CPB, laboratory markers of tissue hypoperfusion, blood gases and body temperature were also recorded. Results: Interstitial muscle tissue oxygen tension (pO2) decreased after the introduction to anaesthesia and, more significantly, during CPB. After the disconnection from CPB at the end of the operation, the pO2 returned to pre-anaesthetic values. During the first hours after admission of the patients to the intensive care unit, the pO2 progressively decreased, reached a minimum value after four hours, and increased slowly thereafter. There was a significant correlation of pO2 with mean arterial blood pressure and blood flow during that time. Conclusion: The result of this first measurement seems to demonstrate that the standard technique of conducting cardiopulmonary bypass produces low muscle oxygen tension and, thus, little perfusion of skeletal muscle. The data also indicate that both high mean arterial blood pressure and high flow are necessary during CPB to ensure skeletal muscle perfusion. The investigation is continuing.

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