A model analysis of aftereffects of high-intensity DC stimulation on action potential of ventricular muscle

1998 ◽  
Vol 45 (2) ◽  
pp. 258-267 ◽  
Author(s):  
I. Sakuma ◽  
T. Haraguchi ◽  
K. Ohuchi ◽  
Y. Fukui ◽  
I. Kodama ◽  
...  
Keyword(s):  
Action Potential ◽  
High Intensity ◽  
Model Analysis ◽  
Ventricular Muscle

scholarly journals Effect of pulsed high intensity focused ultrasound on the nerve compound action potential amplitude and conduction velocity

2021 ◽  
Author(s):  
Steve Tran
Keyword(s):  
Action Potential ◽  
Conduction Velocity ◽  
High Intensity ◽  
Focused Ultrasound ◽  
Compound Action Potential ◽  
Homarus Americanus ◽  
High Intensity Focused Ultrasound ◽  
Nerve Tissue ◽  
Nerve Function ◽  
Compound Action

Therapeutic HIFU has been used as a non-invasive energy modality to compromise nerve function since the 1950s. Several contributions have been made in recent years to characterize these effects on nerve function. In this study, short repeated bursts of HIFU, termed as pulsed high intensity focused ultrasound (pHIFU), was directed at nerve tissue. The pHIFU transducer operated at a central frequency of 1.95 MHz and had a focal length of approximately 12 cm. The ventral nerve cord from the American Lobster (Homarus americanus), n=15, was sonicated cumulatively at 3 exposure times: 1s, 6s, and 16s, at an intensity of 1010 W/cm2, or focal pressure of 5.51 MPa. The compound action potential (CAP) and conduction velocity (CV) were seen to decrease as sonication exposure time to the nerve increased. The experiments performed demonstrate the feasibility to modulate nerve CAP and nerve CV using non-thermal mechanisms of ultrasound.

Excitability and electrical response of ischemic heart muscle

1960 ◽  
Vol 198 (6) ◽  
pp. 1143-1147 ◽  
Author(s):  
Chandler McC. Brooks ◽  
Jerome L. Gilbert ◽  
Martin E. Greenspan ◽  
Gertrude Lange ◽  
Hector M. Mazzella
Keyword(s):  
Action Potential ◽  
Blood Supply ◽  
Heart Muscle ◽  
Action Potentials ◽  
Electrical Response ◽  
Left Ventricular ◽  
Ischemic Heart ◽  
Monophasic Action Potential ◽  
Ventricular Muscle ◽  
Refractory Periods

Measurements were made of the changes in the monophasic action potential, excitability, durations of the refractory periods and conduction times in an area of left ventricular muscle during the development of ischemia subsequent to ligation of the ramus descendens anterior. The degree and duration of the ischemia produced varied greatly and effects were related thereto. It was found that action potentials shortened as did the refractory periods; thresholds fell momentarily and then rose progressively as tissue responsiveness failed due to continuing ischemia. Latency of responses increased, the action potentials decreased in amplitude and alternation occurred before the tissue became completely unresponsive. Early re-establishment of a blood supply caused a reversal of the abnormalities. The significance of these changes to the origin of arrhythmias is discussed.

Effect of High-Intensity X-Radiation on the A Group Fibers of the Frog's Sciatic Nerve

1956 ◽  
Vol 184 (2) ◽  
pp. 333-337 ◽  
Author(s):  
Herbert B. Gerstner
Keyword(s):  
Sciatic Nerve ◽  
Ionizing Radiation ◽  
Action Potential ◽  
Rise Time ◽  
High Intensity ◽  
Dose Range ◽  
Monophasic Action Potential ◽  
Potential Amplitude ◽  
Complete Failure ◽  
Sciatic Nerves

Isolated sciatic nerves of bullfrogs received x-radiation at a dose rate of 9 kr/min. Prior to and following exposure, the monophasic action potential was recorded. In alpha fibers, doses between 75 kr and 200 kr caused a decrease in conduction velocity, an increase in the rise time of the action potential, and an elevated rheobase with shortened chronaxie; the potential amplitude was not obviously affected. In the dose range above 200 kr, the potential amplitude declined rapidly and complete failure of function occurred at about 300 kr. Beta fibers closely resembled alpha fibers in behavior; however, they appeared to be somewhat more radioresistant than a portion of the alpha subdivision. Gamma fibers seemed to be most susceptible to ionizing radiation; their potential disappeared at doses between 150 kr and 200 kr.

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