Role of carotid bodies in control of the neuroendocrine response to exercise

2001 ◽  
Vol 281 (4) ◽  
pp. E742-E748 ◽  
Author(s):  
Yoshiharu Koyama ◽  
Robert H. Coker ◽  
Joshua C. Denny ◽  
D. Brooks Lacy ◽  
Kareem Jabbour ◽  
...  
Keyword(s):  
Steady State ◽  
Glucose Production ◽  
Isotopic Dilution ◽  
Sympathetic Response ◽  
Carotid Bodies ◽  
Anesthetized Dogs ◽  
Arterial Plasma ◽  
Exercise Induced ◽  
Response To Exercise

This study was aimed at assessing the role of carotid body function in neuroendocrine and glucoregulatory responses to exercise. The carotid bodies and associated nerves were removed (CBR, n = 6) or left intact (Sham, n = 6) in anesthetized dogs >16 days before experiments, and infusion and sampling catheters were implanted. Conscious dogs were studied at rest and during 150 min of exercise. Isotopic dilution was used to assess glucose production (Ra) and disappearance (Rd). Arterial glucagon was reduced in CBR compared with Sham at rest (29 ± 3 vs. 47 ± 3 pg/ml). During exercise, glucagon increased more in Sham than in CBR (47 ± 9 vs. 15 ± 2 pg/ml). Cortisol and epinephrine levels were similar in the two groups at rest and during exercise. Basal norepinephrine was similar in CBR and Sham. During exercise, norepinephrine increased by 432 ± 124 pg/ml in Sham, but by only 201 ± 28 pg/ml in CBR. Basal arterial plasma glucose was 108 ± 2 and 105 ± 2 mg/dl in CBR and Sham, respectively. Arterial glucose dropped by 10 ± 3 mg/dl at onset of exercise in CBR ( P < 0.01) but was unchanged in Sham (decrease of 3 ± 2 mg/dl, not significant). Basal glucose kinetics were equal in Sham and CBR. At onset of exercise, Raand Rdwere transiently uncoupled in CBR (i.e., Rd> Ra) but were closely matched in Sham. In steady-state exercise, Raand Rdwere closely matched in both groups. Insulin was equal in the basal period and decreased similarly during exercise. These studies suggest that input from the carotid bodies, or receptors anatomically close to them, 1) is important in control of basal glucagon and the exercise-induced increment in glucagon, 2) is involved in the sympathetic response to exercise, and 3) participates in the non-steady-state coupling of Rato Rd, but 4) is not essential to glucoregulation during sustained exercise.

Metabolic role of the exercise-induced increment in epinephrine in the dog

1988 ◽  
Vol 255 (4) ◽  
pp. E428-E436 ◽  
Author(s):  
J. M. Moates ◽  
D. B. Lacy ◽  
R. E. Goldstein ◽  
A. D. Cherrington ◽  
D. H. Wasserman
Keyword(s):  
Glucose Production ◽  
Plasma Glucagon ◽  
Metabolic Role ◽  
Exercise Period ◽  
Exercise Induced ◽  
Glucagon And Insulin ◽  
Induced Changes ◽  
Response To Exercise ◽  
Rest And Exercise

The role of the exercise-induced increment in epinephrine was studied in five adrenalectomized (ADX) and in six normal dogs (C). Experiments consisted of an 80-min equilibration period, a 40-min basal period, and a 150-min exercise period. ADX were studied with epinephrine replaced to basal levels during rest and to increased levels during exercise to simulate its normal rise (HE) and on a separate day with epinephrine maintained at basal levels throughout the study (BE). Cortisol was replaced during rest and exercise in ADX so as to simulate the levels seen in C. Glucose was infused as needed in ADX to maintain the glycemia evident during exercise in C. Glucose production (Ra) and utilization (Rd) were assessed isotopically. In C, epinephrine had risen by 95 +/- 25 pg/ml by the end of exercise. In HE, the increment in epinephrine (117 +/- 29 pg/ml) was similar to that seen in C, whereas in BE epinephrine fell by 18 +/- 9 pg/ml. Basal norepinephrine levels were 139 +/- 9, 260 +/- 25, and 313 +/- 33 pg/ml in C, HE, and BE, respectively. In response to exercise, norepinephrine increased by nearly twofold in all protocols. Basal and exercise-induced changes in plasma glucagon and insulin were similar in C and ADX. Ra increased similarly in C (5.3 +/- 0.6 mg.kg-1.min-1) and HE (4.9 +/- 0.6 mg.kg-1.min-1). In BE, Ra rose normally for the initial 90 min but then declined resulting in a rise of only 2.9 +/- 0.5 mg.kg-1.min-1 after 150 min of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cardiac lymph and interstitial fluid in lipid metabolism of canine heart

1978 ◽  
Vol 56 (6) ◽  
pp. 1041-1046 ◽  
Author(s):  
Pierre Julien ◽  
Gilles R. Dagenais ◽  
Laimonis Gailis ◽  
Paul-E. Roy
Keyword(s):  
Fatty Acids ◽  
Femoral Vein ◽  
Canine Heart ◽  
Triglyceride Fraction ◽  
Constant Rate ◽  
Arterial Concentration ◽  
Anesthetized Dogs ◽  
Arterial Plasma ◽  
The Relationship

To determine whether cardiac interstitial spaces participate in cardiac fatty acid pool, the relationship between cardiac lymph and arterial plasma free palmitate and triglycerides was studied in anesthetized dogs. [14C]Sucrose, infused at a constant rate in a femoral vein, appeared in the lymph at 90% of its arterial concentration within 60 min. On the other hand, when [1-14C]palmitate was infused at the same rate and at the same site, the ratio of lymph to arterial plasma 14C-labelled free fatty acids (FFA) was only 21% at 60 min and 25% at 120 min, even though the concentrations of endogenous FFA in lymph and arterial plasma were the same. The ratio reached 90% only 24 h after a bolus injection of [3H]palmitate. [1-14C]Palmitate in the lymph triglyceride fraction was only 8% of that in plasma. Although the lymph composition may be influenced by the metabolism of heart muscle, cardiac adipose tissue, and serum lipoproteins, these results indicate the presence of a pool of myocardial fatty acids which may be partly located in the interstitial spaces.

Role of adenosine in coronary autoregulation

1986 ◽  
Vol 250 (4) ◽  
pp. H558-H566 ◽  
Author(s):  
F. L. Hanley ◽  
M. T. Grattan ◽  
M. B. Stevens ◽  
J. I. Hoffman
Keyword(s):  
Steady State ◽  
Adenosine Deaminase ◽  
Low Pressure ◽  
Catalytic Subunit ◽  
Coronary Resistance ◽  
Pressure Flow ◽  
Intracoronary Infusion ◽  
Adenosine Concentration ◽  
Anesthetized Dogs

The role of cardiac interstitial adenosine as an important metabolite in coronary autoregulation has not been established. We therefore measured steady-state cardiac interstitial adenosine concentration at a high and a low coronary inflow pressure using an epicardial diffusion well in anesthetized dogs. Although coronary resistance for the high and low pressure points showed highly significant differences (P less than 0.001), adenosine averaged 302 +/- 98 and 286 +/- 91 (SD) pmol/ml for the high and low pressure points, respectively (P greater than 0.20). Cardiac interstitial adenosine concentration was then measured with and without an intracoronary infusion of adenosine deaminase catalytic subunit. Adenosine averaged 28 +/- 21 (SD) pmol/ml during the infusion compared with 281 +/- 68 during control conditions (P less than 0.001). Finally, pressure-flow relations were obtained with and without the adenosine deaminase infusion, and there was no loss of autoregulation in the pressure of adenosine deaminase. These findings indicate that intracoronary adenosine deaminase markedly reduces interstitial adenosine concentration, that cardiac interstitial adenosine concentration remains constant during autoregulation, and that the coronary bed autoregulates normally when interstitial adenosine is reduced to levels close to zero. We conclude that cardiac interstitial adenosine concentration is not an important component in coronary autoregulation.

Effects of exercise on endothelium and endothelium/smooth muscle cross talk: role of exercise-induced hemodynamics

2011 ◽  
Vol 111 (1) ◽  
pp. 311-320 ◽  
Author(s):  
S. C. Newcomer ◽  
Dick H. J. Thijssen ◽  
D. J. Green
Keyword(s):  
Physical Activity ◽  
Shear Stress ◽  
Wall Stress ◽  
Beneficial Effects ◽  
Exercise Induced ◽  
Response To Exercise ◽  
And Training

Physical activity, exercise training, and fitness are associated with decreased cardiovascular risk. In the context that a risk factor “gap” exists in the explanation for the beneficial effects of exercise on cardiovascular disease, it has recently been proposed that exercise generates hemodynamic stimuli which exert direct effects on the vasculature that are antiatherogenic. In this review we briefly introduce some of the in vitro and in vivo evidence relating exercise hemodynamic modulation and vascular adaptation. In vitro data clearly demonstrate the importance of shear stress as a potential mechanism underlying vascular adaptations associated with exercise. Supporting this is in vivo human data demonstrating that exercise-mediated shear stress induces localized impacts on arterial function and diameter. Emerging evidence suggests that exercise-related changes in hemodynamic stimuli other than shear stress may also be associated with arterial remodeling. Taken together, in vitro and in vivo data strongly imply that hemodynamic influences combine to orchestrate a response to exercise and training that regulates wall stress and peripheral vascular resistance and contributes to the antiatherogenic impacts of physical activity, fitness, and training.

scholarly journals Elevated extracellular potassium prior to muscle contraction reduces onset and steady-state exercise hyperemia in humans

2018 ◽  
Vol 125 (2) ◽  
pp. 615-623 ◽  
Author(s):  
Janée D. Terwoord ◽  
Christopher M. Hearon ◽  
Gary J. Luckasen ◽  
Jennifer C. Richards ◽  
Michael J. Joyner ◽  
...  
Keyword(s):  
Steady State ◽  
Voluntary Contraction ◽  
Extracellular Potassium ◽  
Handgrip Exercise ◽  
Exercise Hyperemia ◽  
Forearm Vascular Conductance ◽  
Response To Exercise ◽  
Exercise In Humans ◽  
Hyperemic Response

The increase in interstitial potassium (K+) during muscle contractions is thought to be a vasodilatory signal that contributes to exercise hyperemia. To determine the role of extracellular K+ in exercise hyperemia, we perfused skeletal muscle with K+ before contractions, such that the effect of any endogenously-released K+ would be minimized. We tested the hypothesis that local, intra-arterial infusion of potassium chloride (KCl) at rest would impair vasodilation in response to subsequent rhythmic handgrip exercise in humans. In 11 young adults, we determined forearm blood flow (FBF) (Doppler ultrasound) and forearm vascular conductance (FVC) (FBF/mean arterial pressure) during 4 min of rhythmic handgrip exercise at 10% of maximal voluntary contraction during 1) control conditions, 2) infusion of KCl before the initiation of exercise, and 3) infusion of sodium nitroprusside (SNP) as a control vasodilator. Infusion of KCl or SNP elevated resting FVC similarly before the onset of exercise (control: 39 ± 6 vs. KCl: 81 ± 12 and SNP: 82 ± 13 ml·min−1·100 mmHg−1; both P < 0.05 vs. control). Infusion of KCl at rest diminished the hyperemic (ΔFBF) and vasodilatory (ΔFVC) response to subsequent exercise by 22 ± 5% and 30 ± 5%, respectively (both P < 0.05 vs. control), whereas SNP did not affect the change in FBF ( P = 0.74 vs. control) or FVC ( P = 0.61 vs. control) from rest to steady-state exercise. These findings implicate the K+ ion as an essential vasodilator substance contributing to exercise hyperemia in humans. NEW & NOTEWORTHY Our findings support a significant and obligatory role for potassium signaling in the local vasodilatory and hyperemic response to exercise in humans.

Role of neutral endopeptidase in exercise-induced bronchoconstriction in asthmatic subjects

1996 ◽  
Vol 81 (2) ◽  
pp. 673-678 ◽  
Author(s):  
H. W. de Gouw ◽  
Z. Diamant ◽  
E. A. Kuijpers ◽  
J. K. Sont ◽  
P. J. Sterk
Keyword(s):  
Recovery Period ◽  
Neutral Endopeptidase ◽  
Bicycle Ergometer ◽  
Forced Expiratory Volume ◽  
Double Blind ◽  
Airway Response ◽  
Membrane Bound ◽  
Exercise Induced ◽  
Response To Exercise

The membrane-bound metalloproteinase, neutral endopeptidase (NEP), is a degrading enzyme of both bronchoconstrictor and bronchodilator peptides within the airways. To examine the role of NEP in exercise-induced bronchoconstriction (EIB) in asthmatic subjects, we used inhaled thiorphan, a NEP inhibitor, as pretreatment to a 6-min standardized exercise challenge. Thirteen clinically stable asthmatic subjects participated in this double-blind, placebo-controlled, crossover study that was performed on 2 days separated by 48 h. Thiorphan was administered by two inhalations of 0.5 ml containing 1.25 mg/ml. Subsequently, exercise was performed on a bicycle ergometer at 40–50% of predicted maximal voluntary ventilation while inhaling dry air (20 degrees C, relative humidity 6%). The airway response to exercise was measured by forced expiratory volume in 1 s (FEV1) every 3 min, up to 30 min postexercise challenge, and was expressed both as the maximal percent fall in FEV1 from baseline and as the area under the time-response curve (AUC) (0–30 min). The acute effects of both pretreatments on baseline FEV1 were not different (P > 0.2), neither was there any difference in maximal percent fall in FEV1 between thiorphan and placebo (P > 0.7). However, compared with placebo, thiorphan reduced the AUC by, on average, 26% [AUC (0–30 min, +/-SE): 213.6 +/- 47.7 (thiorphan) and 288.6 +/- 46.0%fall.h (placebo); P = 0.047]. These data indicate that NEP inhibition by thiorphan reduces EIB during the recovery period. This suggests that bronchodilator NEP substrates, such as vasoactive intestinal polypeptide or atrial natriuretic peptide, modulate EIB in patients with asthma.

Exercise-induced fall in insulin and hepatic carbohydrate metabolism during muscular work

1989 ◽  
Vol 256 (4) ◽  
pp. E500-E509 ◽  
Author(s):  
D. H. Wasserman ◽  
P. E. Williams ◽  
D. B. Lacy ◽  
R. E. Goldstein ◽  
A. D. Cherrington
Keyword(s):  
Treadmill Exercise ◽  
Vena Cava ◽  
Glucose Production ◽  
Suppressive Effect ◽  
Hepatic Veins ◽  
Gluconeogenesis From Alanine ◽  
Exercise Induced ◽  
Arteriovenous Difference ◽  
Intraportal Infusion

To examine the role of the exercise-induced fall in insulin, dogs were studied during 150 min of treadmill exercise alone (C) or with insulin clamped at basal levels by an intraportal infusion so as to prevent the normal fall in its concentration (IC). To counteract the suppressive effect of insulin on glucagon release, glucagon was replaced intraportally in a separate group of dogs in which insulin levels were clamped (IC + G). In all dogs, catheters were placed in an artery and in the portal and hepatic veins for sampling and in the vena cava and the portal vein for infusion purposes. Glucose production (Ra) and gluconeogenesis were assessed with isotope and arteriovenous difference techniques. In C, insulin fell 5 +/- 2 microU/ml by the end of exercise and was unchanged in IC (delta 0 +/- 2 microU/ml) and IC + G (delta 0 +/- 1 microU/ml). Glucagon rose 54 +/- 11 pg/ml with exercise in C and was unchanged in IC (delta - 4 +/- 11 pg/ml), and normal increments were restored in IC + G (delta 55 +/- 10 pg/ml). Catecholamines and cortisol rose similarly in all groups. Ra increased by an average of 4.0 +/- 0.4, 0.9 +/- 0.3, and 1.8 +/- 0.4 mg.kg-1.min-1 during exercise in C, IC, and IC + G, respectively. Gluconeogenesis from alanine rose by 212 +/- 34, 91 +/- 39, and 184 +/- 47% with exercise in C, IC, and IC + G.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Role of Autonomic Function in Exerciseinduced Endogenous Analgesia: A Case-control Study in Myalgic Encephalomyelitis⁄Chronic Fatigue Syndrome and Healthy People

2017 ◽  
Vol 3 (20;3) ◽  
pp. E389-E399 ◽  
Author(s):  
Jo Nijs
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Diastolic Blood Pressure ◽  
Chronic Fatigue ◽  
Fatigue Syndrome ◽  
Exercise Induced ◽  
Response To Exercise ◽  
Endogenous Analgesia

Background: Patients with myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) are unable to activate brain-orchestrated endogenous analgesia (or descending inhibition) in response to exercise. This physiological impairment is currently regarded as one factor explaining postexertional malaise in these patients. Autonomic dysfunction is also a feature of ME/CFS. Objectives: This study aims to examine the role of the autonomic nervous system in exerciseinduced analgesia in healthy people and those with ME/CFS, by studying the recovery of autonomic parameters following aerobic exercise and the relation to changes in self-reported pain intensity. Study Design: A controlled experimental study. Setting: The study was conducted at the Human Physiology lab of the Vrije Universiteit Brussel. Methods: Twenty women with ME/CFS- and 20 healthy, sedentary controls performed a submaximal bicycle exercise test known as the Aerobic Power Index with continuous cardiorespiratory monitoring. Before and after the exercise, measures of autonomic function (i.e., heart rate variability, blood pressure, and respiration rate) were performed continuously for 10 minutes and self-reported pain levels were registered. The relation between autonomous parameters and self-reported pain parameters was examined using correlation analysis. Results: Some relationships of moderate strength between autonomic and pain measures were found. The change (post-exercise minus pre-exercise score) in pain severity was correlated (r = .580, P = .007) with the change in diastolic blood pressure in the healthy group. In the ME/CFS group, positive correlations between the changes in pain severity and low frequency (r = .552, P = .014), and between the changes in bodily pain and diastolic blood pressure (r = .472, P = .036), were seen. In addition, in ME/CHFS the change in headache severity was inversely correlated (r = -.480, P = .038) with the change in high frequency heart rate variability. Limitations: Based on the cross-sectional design of the study, no firm conclusions can be drawn on the causality of the relations. Conclusions: Reduced parasympathetic reactivation during recovery from exercise is associated with the dysfunctional exercise-induced analgesia in ME/CFS. Poor recovery of diastolic blood pressure in response to exercise, with blood pressure remaining elevated, is associated with reductions of pain following exercise in ME/CFS, suggesting a role for the arterial baroreceptors in explaining dysfunctional exercise-induced analgesia in ME/CFS patients. Key words: Aerobic exercise, aerobic power index, autonomic nervous system, exercise-induced analgesia, exercise-induced hypoalgesia, fibromyalgia, heart rate variability, stress-induced analgesia, pain Pain

scholarly journals Taming the “sleeping giant”: the role of endothelin-1 in the regulation of skeletal muscle blood flow and arterial blood pressure during exercise

2013 ◽  
Vol 304 (1) ◽  
pp. H162-H169 ◽  
Author(s):  
Zachary Barrett-O'Keefe ◽  
Stephen J. Ives ◽  
Joel D. Trinity ◽  
Garrett Morgan ◽  
Matthew J. Rossman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiovascular Response ◽  
Muscle Blood Flow ◽  
Knee Extensor ◽  
Leg Blood Flow ◽  
Arterial Blood ◽  
Before And After ◽  
Exercise Induced ◽  
Response To Exercise

The cardiovascular response to exercise is governed by a combination of vasodilating and vasoconstricting influences that optimize exercising muscle perfusion while protecting mean arterial pressure (MAP). The degree to which endogenous endothelin (ET)-1, the body's most potent vasoconstrictor, participates in this response is unknown. Thus, in eight young (24 ± 2 yr), healthy volunteers, we examined leg blood flow, MAP, tissue oxygenation, heart rate, leg arterial-venous O2 difference, leg O2 consumption, pH, and net ET-1 and lactate release at rest and during knee extensor exercise (0, 5, 10, 15, 20, and 30 W) before and after an intra-arterial infusion of BQ-123 [ET subtype A (ETA) receptor antagonist]. At rest, BQ-123 did not evoke a change in leg blood flow or MAP. During exercise, net ET-1 release across the exercising leg increased approximately threefold. BQ-123 increased leg blood flow by ∼20% across all work rates (changes of 113 ± 76, 176 ± 83, 304 ± 108, 364 ± 130, 502 ± 117, and 570 ± 178 ml/min at 0, 5, 10, 15, 20, and 30 W, respectively) and attenuated the exercise-induced increase in MAP by ∼6%. The increase in leg blood flow was accompanied by a ∼9% increase in leg O2 consumption with an unchanged arterial-venous O2 difference and deoxyhemoglobin, suggesting a decline in intramuscular efficiency after ETA receptor blockade. Together, these findings identify a significant role of the ET-1 pathway in the cardiovascular response to exercise, implicating vasoconstriction via the ETA receptor as an important mechanism for both the restraint of blood flow in the exercising limb and maintenance of MAP in healthy, young adults.

Modulation of exercise tachycardia by vasopressin in the nucleus tractus solitarii

1997 ◽  
Vol 273 (4) ◽  
pp. R1271-R1282 ◽  
Author(s):  
Daniel L. Dufloth ◽  
Mariana Morris ◽  
Lisete C. Michelini
Keyword(s):  
Brain Stem ◽  
Acute Exercise ◽  
Treadmill Exercise ◽  
Nucleus Tractus Solitarii ◽  
Male Rats ◽  
Exercise Tachycardia ◽  
Pressor Responses ◽  
Exercise Induced ◽  
Response To Exercise

Our objective was to study the role of vasopressinergic synapses at the nucleus tractus solitarii (NTS) in the modulation of exercise-induced tachycardia. We evaluated the effect of NTS administration of vasopressin (AVP) or vasopressin antagonist (AVPant) on heart rate (HR) and mean arterial pressure (MAP) responses during dynamic exercise in male rats with chronic arterial and NTS cannulas. Sedentary (S) and trained (T) animals were tested at three or four exercise levels (from 0.4 up to 1.4 km/h) after NTS injection of AVP or AVPant 20–30 min before treadmill exercise. Plasma and regional brain levels of AVP were measured in separate groups of S and T rats at rest and immediately after acute exercise. When administered into the NTS, exogenous AVP (20 pmol) caused a small but significant decrease in baseline HR and potentiated the tachycardiac response to mild to moderate exercise intensities (on average, increases of 35–46 beats/min over control tachycardic response). The potentiation of exercise tachycardia by AVP was long lasting and more pronounced in T than in S rats. Even 2 days after NTS AVP injection, there was evidence for an alteration in the HR response to exercise. Mediation by V1 receptors was supported by the blunted tachycardiac response to exercise after administration of a V1 antagonist d(CH2)5Tyr MeAVP into the NTS in both T and S rats (average reductions of 23–34 and 13–19 beats/min below control tachycardia, respectively). No changes were observed in baseline MAP or the exercise-induced pressor responses. There were specific changes in brain stem AVP levels that were related to the exercise treatment. T rats showed a marked increase in dorsal and ventral brain stem AVP content after acute exercise. There were no changes in hypothalamus, median eminence, posterior pituitary, or plasma AVP. These data indicate that vasopressinergic synapses and V1 receptors in the NTS are involved in the potentiation of tachycardic response to exercise. The vasopressinergic mechanism operates in both S and T rats, but training alters the sensitization of V1receptors by AVP.

Sign in / Sign up

Export Citation Format

Share Document