scholarly journals Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart

2018 ◽  
Vol 9 ◽  
Author(s):  
James Winter ◽  
Martin J. Bishop ◽  
Catherine D. E. Wilder ◽  
Christopher O'Shea ◽  
Davor Pavlovic ◽  
...  
Keyword(s):  
Action Potential ◽  
Nervous Regulation ◽  
Sympathetic Nervous ◽  
Intact Heart

Regional electromechanical alternans in anesthetized pig hearts: modulation by mechanoelectric feedback

1994 ◽  
Vol 267 (5) ◽  
pp. H1726-H1735 ◽  
Author(s):  
C. F. Murphy ◽  
M. J. Lab ◽  
S. M. Horner ◽  
D. J. Dick ◽  
F. G. Harrison
Keyword(s):  
Left Ventricle ◽  
Action Potential ◽  
Monophasic Action Potential ◽  
Mechanical Activity ◽  
Strain Gauges ◽  
Atrial Pacing ◽  
Mechanoelectric Feedback ◽  
Pulsus Alternans ◽  
Electrical Alternans ◽  
Intact Heart

Electrical and mechanical alternans have often been found to coexist. However, the factors controlling their interdependence are not known. In this study we measure regional electrical and mechanical activity during mechanical alternans to investigate this relationship. Mechanical alternans was induced by rapid atrial pacing in 18 anesthetized, open-chest pigs. Regional segmental contraction and monophasic action potential were measured in three areas of left ventricle using epicardial tripodal strain gauges and suction electrodes. Electrical alternans always accompanied pulsus alternans. The phase of electrical alternans was not related to any measure of regional mechanical activity but did show a constant discordant relation to peak ventricular pressure. This suggested that mechanically dependent changes in action potential duration (mechanoelectric feedback) may be important in modulation electrical alternans. In support of this, pulsus alternans simulated by clamping the proximal aorta on alternate beats was associated with electrical alternans comparable to that produced with rapid atrial pacing. Mechanoelectric feedback modulates regional electrophysiology in the intact heart and may be important in the generation of electrical alternans.

Changes in ventricular repolarization during acidosis and low-flow ischemia

1998 ◽  
Vol 275 (2) ◽  
pp. H551-H561 ◽  
Author(s):  
Hugh W. L. Bethell ◽  
Jamie I. Vandenberg ◽  
Gerry A. Smith ◽  
Andrew A. Grace
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Respiratory Acidosis ◽  
Control Flow ◽  
Low Flow ◽  
Channel Blockers ◽  
Monophasic Action Potentials ◽  
Ferret Heart ◽  
Action Potential Repolarization ◽  
Intact Heart

Myocardial ischemia, primarily a metabolic insult, is also defined by altered cardiac mechanical and electrical activity. We have investigated the metabolic contributions to the electrophysiological changes during low-flow ischemia (7.5% of the control flow) using31P NMR spectroscopy to monitor metabolic parameters, suction electrodes to study epicardial monophasic action potentials, and 86Rb as a tracer for K+-equivalent efflux during low-flow ischemia in the Langendorff-perfused ferret heart. Shortening of the action potential duration at 90% repolarization (APD90) was most marked between 1 and 5 min after induction of ischemia, at which time it shortened from 261 ± 4 to 213 ± 8 ms. The period of marked APD90 shortening was accompanied by a fivefold increase in the rate of86Rb efflux, both of which were inhibited by the ATP-sensitive K+(KATP)-channel blockers glibenclamide and 5-hydroxydecanoate (5-HD), as well as by a significant fall in intracellular pH (pHi) from 7.14 ± 0.02 to 6.83 ± 0.03 but no change in intracellular ATP concentration ([ATP]i). We therefore investigated whether a fall in pHi could be the metabolic change responsible for modulating cardiac KATP channel activity in the intact heart during ischemia. Both metabolic (30 mM lactate added to extracellular solution) and respiratory ([Formula: see text] increased to 15%) acidosis caused an initial lengthening of APD90 to 112 ± 1.5 and 113 ± 0.9%, respectively, followed by shortening during continued acidosis to 106 ± 1.2 and 106 ± 1.4%, respectively. The shortening of APD90 during continued acidosis was inhibited by glibenclamide, consistent with acidosis causing activation of KATP channels at normal [ATP]i. The similar responses to metabolic (induced by adding either l- or d-lactate) and respiratory acidosis suggest that lactate has no independent metabolic effect on action potential repolarization.

Combining Monophasic Action Potential Recordings With Pacing to Demonstrate Delayed Afterdepolarizations and Triggered Arrhythmias in the Intact Heart

Circulation ◽  
1995 ◽  
Vol 92 (9) ◽  
pp. 2697-2704 ◽  
Author(s):  
S.H. Marieke de Groot ◽  
Marc A. Vos ◽  
Anton P.M. Gorgels ◽  
Jet D.M. Leunissen ◽  
Bert J. van der Steld ◽  
...  
Keyword(s):  
Action Potential ◽  
Monophasic Action Potential ◽  
Triggered Arrhythmias ◽  
Delayed Afterdepolarizations ◽  
Intact Heart

Sympathetic nervous regulation of retinal blood flow in aged rats

1992 ◽  
Vol 17 ◽  
pp. 205
Author(s):  
Harumi Hotta ◽  
Osamu Inanami ◽  
Hideki Ito ◽  
Akio Sato
Keyword(s):  
Blood Flow ◽  
Retinal Blood Flow ◽  
Aged Rats ◽  
Nervous Regulation ◽  
Sympathetic Nervous

scholarly journals The action-potential duration and contractile response of the intact heart related to the preceding interval and the preceding beat in the dog and cat

1981 ◽  
Vol 314 (1) ◽  
pp. 481-500 ◽  
Author(s):  
Gijs Elzinga ◽  
Max J. Lab ◽  
Mark I. M. Noble ◽  
Demetrios E. Papadoyannis ◽  
John Pidgeon ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Contractile Response ◽  
Preceding Interval ◽  
Intact Heart

Influence of noise and vibration on nervous regulation of heart

2019 ◽  
pp. 19-23 ◽  
Author(s):  
A. V. Melentev ◽  
P. V. Serebryakov ◽  
A. V. Zheglova
Keyword(s):  
Nervous System ◽  
Cardiac Rhythm ◽  
Work Conditions ◽  
Negative Influence ◽  
Nervous Regulation ◽  
Noise And Vibration ◽  
Cardiac Regulation ◽  
Sympathetic Nervous ◽  
Influence Of Noise

The authors studied influence of noise and vibration on cardiac nervous regulation in workers exposed to unfavourable work conditions. Evidence is that noise and vibration induce cardioneuropathy signs manifested in lower general vegetative influence on cardiac rhythm, as well as in its shift to higher activity of sympathetic nervous system. More marked changes are seen at daytime. Findings are that in combined influence of noise and vibration on humans, priority role of negative influence on cardiac regulation is taken by vibration factor.

How to sample the entire length of a single muscle fiber quick-frozen after electrical point stimulation for high resolution EM

1992 ◽  
Vol 50 (1) ◽  
pp. 776-777
Author(s):  
Joachim R. Sommer ◽  
Teresa High ◽  
Betty Scherer ◽  
Isaiah Taylor ◽  
Rashid Nassar
Keyword(s):  
Skeletal Muscle ◽  
High Resolution ◽  
Action Potential ◽  
Muscle Fiber ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Electrical Field Stimulation ◽  
Skeletal Muscle Fiber ◽  
Freeze Dried ◽  
Quick Freezing

We have developed a model that allows the quick-freezing at known time intervals following electrical field stimulation of a single, intact frog skeletal muscle fiber isolated by sharp dissection. The preparation is used for studying high resolution morphology by freeze-substitution and freeze-fracture and for electron probe x-ray microanlysis of sudden calcium displacement from intracellular stores in freeze-dried cryosections, all in the same fiber. We now show the feasibility and instrumentation of new methodology for stimulating a single, intact skeletal muscle fiber at a point resulting in the propagation of an action potential, followed by quick-freezing with sub-millisecond temporal resolution after electrical stimulation, followed by multiple sampling of the frozen muscle fiber for freeze-substitution, freeze-fracture (not shown) and cryosectionmg. This model, at once serving as its own control and obviating consideration of variances between different fibers, frogs etc., is useful to investigate structural and topochemical alterations occurring in the wake of an action potential.

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