scholarly journals Comparison of the Reflexes Elicited from Combined or Separate Stimulation of the Aortic and Carotid Chemoreceptors on Myocardial Contractility, Cardiac Output and Systemic Resistance

1967 ◽  
Vol 20 (2) ◽  
pp. 214-227 ◽  
Author(s):  
SHLOMO STERN ◽  
ELLIOT RAPAPORT
Keyword(s):  
Cardiac Output ◽  
Myocardial Contractility ◽  
Systemic Resistance ◽  
Carotid Chemoreceptors ◽  
Stimulation Of

The relative roles of external and internal CO2versusH+ in eliciting the cardiorespiratory responses ofSalmo salarandSqualus acanthiasto hypercarbia

2001 ◽  
Vol 204 (22) ◽  
pp. 3963-3971 ◽  
Author(s):  
S. F. Perry ◽  
J. E. McKendry
Keyword(s):  
Cardiac Output ◽  
Sea Water ◽  
Buccal Cavity ◽  
Respiratory Acidosis ◽  
Systemic Resistance ◽  
Measured Variable ◽  
Cardiorespiratory Responses ◽  
Arterial Blood ◽  
Water Ph ◽  
Stimulation Of

SUMMARYFish breathing hypercarbic water encounter externally elevated PCO2 and proton levels ([H+]) and experience an associated internal respiratory acidosis, an elevation of blood PCO2 and [H+]. The objective of the present study was to assess the potential relative contributions of CO2versus H+ in promoting the cardiorespiratory responses of dogfish (Squalus acanthias) and Atlantic salmon (Salmo salar) to hypercarbia and to evaluate the relative contributions of externally versus internally oriented receptors in dogfish.In dogfish, the preferential stimulation of externally oriented branchial chemoreceptors using bolus injections (50 ml kg–1) of CO2-enriched (4 % CO2) sea water into the buccal cavity caused marked cardiorespiratory responses including bradycardia (–4.1±0.9 min–1), a reduction in cardiac output (–3.2±0.6 ml min–1 kg–1), an increase in systemic vascular resistance (+0.3±0.2 mmHg ml min–1 kg–1), arterial hypotension (–1.6±0.2 mmHg) and an increase in breathing amplitude (+0.3±0.09 mmHg) (means ± s.e.m., N=9–11). Similar injections of CO2-free sea water acidified to the corresponding pH of the hypercarbic water (pH 6.3) did not significantly affect any of the measured cardiorespiratory variables (when compared with control injections). To preferentially stimulate putative internal CO2/H+ chemoreceptors, hypercarbic saline (4 % CO2) was injected (2 ml kg–1) into the caudal vein. Apart from an increase in arterial blood pressure caused by volume loading, internally injected CO2 was without effect on any measured variable.In salmon, injection of hypercarbic water into the buccal cavity caused a bradycardia (–13.9±3.8 min–1), a decrease in cardiac output (–5.3±1.2 ml min–1 kg–1), an increase in systemic resistance (0.33±0.08 mmHg ml min–1 kg–1) and increases in breathing frequency (9.7±2.2 min–1) and amplitude (1.2±0.2 mmHg) (means ± s.e.m., N=8–12). Apart from a small increase in breathing amplitude (0.4±0.1 mmHg), these cardiorespiratory responses were not observed after injection of acidified water.These results demonstrate that, in dogfish and salmon, the external chemoreceptors linked to the initiation of cardiorespiratory responses during hypercarbia are predominantly stimulated by the increase in water PCO2 rather than by the accompanying decrease in water pH. Furthermore, in dogfish, the cardiorespiratory responses to hypercarbia are probably exclusively derived from the stimulation of external CO2 chemoreceptors, with no apparent contribution from internally oriented receptors.

scholarly journals Interactional mechanisms of Paenibacillus polymyxa SC2 and pepper (Capsicum annuum L.) suggested by transcriptomics

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hu Liu ◽  
Yufei Li ◽  
Ke Ge ◽  
Binghai Du ◽  
Kai Liu ◽  
...  
Keyword(s):  
Capsicum Annuum ◽  
Biofilm Formation ◽  
Rhizosphere Soil ◽  
Paenibacillus Polymyxa ◽  
Systemic Resistance ◽  
Expression Of Genes ◽  
Transcription Factor Genes ◽  
Transcription Regulators ◽  
Relationship Of ◽  
Stimulation Of

Abstract Background Paenibacillus polymyxa SC2, a bacterium isolated from the rhizosphere soil of pepper (Capsicum annuum L.), promotes growth and biocontrol of pepper. However, the mechanisms of interaction between P. polymyxa SC2 and pepper have not yet been elucidated. This study aimed to investigate the interactional relationship of P. polymyxa SC2 and pepper using transcriptomics. Results P. polymyxa SC2 promotes growth of pepper stems and leaves in pot experiments in the greenhouse. Under interaction conditions, peppers stimulate the expression of genes related to quorum sensing, chemotaxis, and biofilm formation in P. polymyxa SC2. Peppers induced the expression of polymyxin and fusaricidin biosynthesis genes in P. polymyxa SC2, and these genes were up-regulated 2.93- to 6.13-fold and 2.77- to 7.88-fold, respectively. Under the stimulation of medium which has been used to culture pepper, the bacteriostatic diameter of P. polymyxa SC2 against Xanthomonas citri increased significantly. Concurrently, under the stimulation of P. polymyxa SC2, expression of transcription factor genes WRKY2 and WRKY40 in pepper was up-regulated 1.17-fold and 3.5-fold, respectively. Conclusions Through the interaction with pepper, the ability of P. polymyxa SC2 to inhibit pathogens was enhanced. P. polymyxa SC2 also induces systemic resistance in pepper by stimulating expression of corresponding transcription regulators. Furthermore, pepper has effects on chemotaxis and biofilm formation of P. polymyxa SC2. This study provides a basis for studying interactional mechanisms of P. polymyxa SC2 and pepper.

Invasive Hemodynamic Monitoring in the Intensive Care Unit

2018 ◽  
Author(s):  
Michael C Chang ◽  
Mary Garland
Keyword(s):  
Cardiac Output ◽  
Central Venous Catheter ◽  
Pulmonary Artery ◽  
Stroke Volume ◽  
Myocardial Contractility ◽  
Venous Catheter ◽  
Pulse Contour ◽  
Stroke Work ◽  
Central Venous ◽  
Bedside Clinician

Optimal support of critically ill surgical patients with cardiovascular dysfunction requires that the bedside clinician have both a clear understanding of basic cardiovascular physiology and thorough knowledge of the information available from invasive hemodynamic monitors, including the advantages and pitfalls of each system. Assessment of hemodynamic function in underperfused patients should start with a quantitative assessment of global cardiovascular function. Global variables can be flow derived (e.g., cardiac output), pressure derived (e.g., systolic blood pressure), or both (e.g., ventricular stroke work and power). Any assessment consistent with inadequate global hemodynamic performance should be followed by analysis of the independent determinants of cardiovascular function. These independent determinants include heart rate, preload, afterload, and myocardial contractility. Invasive hemodynamic monitors allow the bedside clinician to measure and quantitate various combinations of global performance and the determinants of cardiac function depending on the monitoring system employed. Central venous lines enable measurement of central venous pressure but limited measure of right ventricular preload. Pulmonary artery catheters offer information pertaining to several global measures and independent determinants. Devices that depend on pulse contour wave analysis, when coupled with a central venous catheter, can measure cardiac output and preload in the context of measurements of stroke volume. However, being invasive, each device carries some degree of risk to the patient, and each monitoring technique employed via these devices carries pitfalls in both measurement and interpretation. It is incumbent upon the bedside clinician to understand the physiologic derangements affecting the patient and the utility and pitfalls of the information available from each device when selecting monitoring systems to be used in any given patient and the supportive therapy that ensues. This review contains 3 figures, 1 table, and 28 references. Key words: afterload, cardiac output, central venous catheter, hemodynamic monitor, myocardial contractility, perfusion, preload, pulmonary artery catheter, pulse contour analysis, stroke volume, stroke volume variability, stroke work, ventricular power 

Cardiovascular hemodynamics in the fetal lamb before and after lung expansion

1965 ◽  
Vol 208 (1) ◽  
pp. 122-129 ◽  
Author(s):  
N. S. Assali ◽  
John A. Morris ◽  
Russell Beck
Keyword(s):  
Cardiac Output ◽  
Vascular Resistance ◽  
Lung Ventilation ◽  
Systemic Resistance ◽  
Cardiovascular Hemodynamics ◽  
Cord Clamping ◽  
Lung Expansion ◽  
Fetal Lamb ◽  
Before And After ◽  
The Right

Cardiovascular hemodynamic studies were carried out on fetal lambs before and after lung ventilation as well as before and after cord clamping. The findings are as follows: 1) Before lung expansion, pressures, output, and work in the right side of the heart are greater than those in the left side. This relation is reversed promptly after lung expansion. 2) When compared to adults, effective fetal cardiac output is high before lung expansion and falls significantly after lung expansion. 3) In the fetus, total pulmonary vascular resistance is considerably higher than systemic resistance. This relation is reversed immediately after lung expansion. 4) In the fetus, the flow of blood in the aorta and pulmonary artery is largely governed by inertial factors. 5) Cord clamping increases systemic resistance through elimination of low vascular resistance of the placental bed.

Effect of PEEP on discharge of pulmonary C-fibers in dogs

1985 ◽  
Vol 59 (4) ◽  
pp. 1085-1089 ◽  
Author(s):  
M. P. Kaufman ◽  
G. A. Ordway ◽  
T. G. Waldrop
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Impulse Activity ◽  
Vena Cava ◽  
Laboratory Animals ◽  
Positive End Expiratory Pressure ◽  
Firing Rates ◽  
C Fibers ◽  
Anesthetized Dogs ◽  
Stimulation Of

Although positive end-expiratory pressure (PEEP) is believed to depress cardiac output and arterial pressure by compressing the vena cava and the heart, it is unclear whether PEEP also depresses these variables by a reflex arising from an inflation-induced stimulation of pulmonary C-fibers. We therefore recorded the impulse activity of 17 pulmonary C-fibers in barbiturate-anesthetized dogs with closed chests, while we placed the expiratory outlet of a ventilator under 5–30 cmH2O. Increasing PEEP in a ramp-like manner stimulated 12 of the 17 pulmonary C-fibers, with activity increasing from 0.0 +/- 0.1 to 0.9 +/- 0.2 imp/s when end-expiratory pressure equaled 15 cmH2O. When PEEP was increased in a stepwise manner to 15–20 cmH2O and maintained at this pressure for 15 min, pulmonary C-fibers increased their firing rates, but the effect was small averaging 0.2–0.3 imp/s after the 1st min of this maneuver. We conclude that pulmonary C-fibers are unlikely to be responsible for causing much of the decreases in cardiac output and arterial pressure evoked by sustained periods of PEEP in both patients and laboratory animals. These C-fibers, however, are likely to be responsible for causing the reflex decreases in these variables evoked by sudden application of PEEP.

Effect of baroreceptor activity on ventilatory response to chemoreceptor stimulation

1975 ◽  
Vol 39 (3) ◽  
pp. 411-416 ◽  
Author(s):  
D. Heistad ◽  
F. M. Abboud ◽  
A. L. Mark ◽  
P. G. Schmid
Keyword(s):  
Arterial Pressure ◽  
Ventilatory Response ◽  
Carotid Bifurcation ◽  
Carotid Chemoreceptors ◽  
Ventilatory Responses ◽  
Before And After ◽  
Cervical Vagotomy ◽  
Anesthetized Dogs ◽  
Baroreceptor Activation ◽  
Stimulation Of

This study tested the hypothesis that ventilatory responses to chemoreceptor stimulation are affected by the level of arterial pressure and degree of baroreceptor activation. Carotid chemoreceptors were stimulated by injection of nicotine into the common carotid artery of anesthetized dogs. Arterial pressure was reduced by bleeding the animals and raised by transient occlusion of the abdominal aorta. The results indicate that ventilatory responses to chemoreceptor stimulation were augmented by hypotension and depressed by hypertension. In additional studies we excluded the possibility that the findings were produced by a direct effect of changes in arterial pressure on chemoreceptors. Both carotid bifurcations were perfused at constant flow. In one carotid bifurcation, perfusion pressure was raised to stimulate carotid sinus baroreceptors. In the other carotid bifurcation, pressure was constant and nicotine was injected to stimulate carotid chemoreceptors. Stimulation of baroreceptors on one side attenuated the ventilatory response to stimulation of contralateral chemoreceptors. This inhibition was observed before and after bilateral cervical vagotomy. We conclude that there is a major central interaction between baroreceptor and chemoreceptor reflexes so that changes in baroreceptor activity modulate ventilatory responses to chemoreceptor stimulation.

THE CARDIAC OUTPUT AND CAROTID AND TIBIAL BLOOD PRESSURE OF THE TURKEY

1963 ◽  
Vol 41 (11) ◽  
pp. 2337-2341 ◽  
Author(s):  
Elwood W. Speckmann ◽  
Robert K. Ringer
Keyword(s):  
Body Weight ◽  
Cardiac Output ◽  
Pulse Pressure ◽  
Mature Male ◽  
Systemic Resistance ◽  
Hemodynamic Parameters ◽  
Radioactive Phosphorus ◽  
Arterial Blood ◽  
Tibial Arteries ◽  
The Mean

The cardiac output of untreated mature male Broad Breasted Bronze (BBB) turkeys was determined by an isotope dilution technique using radioactive phosphorus (P32). A Geiger–Mueller tube was connected to a rate meter which in turn was connected to a moving graph to continuously record the indicator concentration, thus obtaining the initial dilution curve. Posterior tibial and common carotid arterial blood pressures were measured directly and were recorded simultaneously with the cardiac output determinations by means of two strain gauges connected to a recording polygraph.From the cardiovascular measurements systemic resistance was calculated. The mean cardiac output of the mature male BBB turkey was 231 ml per kg body weight0.734 per minute. The mean carotid hemodynamic parameters were: systolic BP, 302 mm Hg; diastolic BP, 204 mm Hg; and pulse pressure, 98 mm Hg. Heart rate was 149 beats per minute. The mean tibial hemodynamic parameters were; systolic BP, 286 mm Hg; diastolic BP, 200 mm Hg; and pulse pressure, 85 mm Hg. The mean systemic resistance units were 0.17 and 0.16 for carotid and tibial arteries respectively on a bird basis and 1.13 and 1.08 respectively per kg body weight0.734.

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