Rheobase


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rheobase

[′rē·ō‚bās]
(physiology)
The intensity of the steady current just sufficient to excite a tissue when suddenly applied.

Rheobase

 

the minimum potential of direct electric current necessary to produce excitation in living tissues. The concept was introduced into physiology in 1909 by L. Lapicque, who in studies on the minimum threshold of excitable tissues determined the dependence between the intensity of a current and the duration of the action of a current.

The rheobase, like the chronaxy, gives an idea of tissue and organ excitability from the threshold of the intensity and duration of stimulation. It corresponds to the stimulation threshold and is expressed in volts or milliamperes. Its value can be computed from the formula i = a/t + b, where i is the current potential, t is the duration of the action of a current, and a and b are constants determined by the properties of a tissue. The constant b is the rheobase because with prolonged stimulation by a current, the a/t ratio will be very low and i will be virtually equal to b. The rheobase often refers to the threshold values of other stimuli besides those that are electric.

References in periodicals archive ?
In the STZ-induced diabetes model used herein, both chronaxy and rheobase were increased in the SN.
The percent difference between sessions for the rheobase voltage ranged from 5.3 to 36.2 percent for the median nerve and 1.7 to 66.7 percent for the ulnar nerve.
The average rheobase current was 1.3 [+ or -] 0.7 mA.
Given the significant tissue impedance when using surface stimulation, a much higher rheobase voltage was required in the present study.
The average rheobase voltage from the median nerve was significantly lower than from the ulnar nerve.
The protocol for obtaining the strength-duration curves was modified partway through testing in response to observations that many of the trials contained data points primarily in the linear portion of the strength-duration curve, near the rheobase voltage.
Panels E and F show effects of EOLs (60 [micro]g/mL) and thymol (60 [micro]g/mL; 0.4 mM) on rheobase and chronaxie.
At the end of 180 min exposure to EOLa and citral, rheobase was increased to 3.7 [+ or -] 0.09 (n=7) and 4.6 [+ or -] 0.54 V (n=9), respectively.
Alterations in rheobase (A, B) and chronaxy (C, D) after exposure to essential oil of Lippia alba (EOLa) and citral.