In vivo recording of electrical activity of canine tracheal smooth muscle

Abstract

Electrical activity of the tracheal smooth muscle was studied using extracellular bipolar electrodes in 37 decerebrate, paralyzed, and mechanically ventilated dogs. A spontaneous oscillatory potential that consisted of a slow sinusoidal wave of 0.57 +/- 0.13 (SD) Hz mean frequency but lacked a fast spike component was recorded from 15 dogs. Lung collapse accomplished by bilateral pneumothoraxes evoked or augmented the slow potentials that were associated with an increase in tracheal muscle contraction in 26 dogs. This suggests that the inputs from the airway mechanoreceptors reflexly activate the tracheal smooth muscle cells. Bilateral vagal transection abolished both the spontaneous and the reflexly evoked slow waves and provided relaxation of the tracheal smooth muscle. Electrical stimulation of the distal nerve with a train pulse (0.5 ms, 1-30 Hz) evoked slow-wave oscillatory potentials accompanied by a contraction of the tracheal smooth muscle in all the experimental animals. Our observations in this in vivo study confirm that the electrical activity of tracheal smooth muscle consists of slow oscillatory potentials and that tracheal contraction is at least partly coupled to the slow-wave activity of the smooth muscle.

Single Potential Analysis of Cavernous Electrical Activity

“…In normal subjects a consistent pattern of electrical activity was observed that was comparable to other smooth muscle organs, such as ureter, trachea or bowel [10][11][12]. During flaccidity, a high frequent basic activity with a low amplitude was found.…”

“…Also, the similarity of potentials recorded with needle electrodes and surface electrodes show that these recordings are of electrical and not of myogenic (movement) origin. Finally, cavernous smooth muscle electrical activity parallels elec trical activity recorded from other smooth muscle organs like ureter, trachea or stomach [10][11][12],…”

“…Many studies in different organ systems show that potentials of smooth muscle origin can be recorded [6][7][8][10][11][12], With respect to cavernous smooth muscle, there is also a growing body of evidence that cavernous electrical activity can be recorded with reproducible results [6][7][8]. The similarity of cavernous smooth muscle potentials in normal subjects during flaccidity and the uniform changes after induction of tumescence by audiovisual sexual stimu lation or intracavemous injection of vasoactive substances strongly suggest that the recordings are not artifacts.…”

Computergestützte Auswertung des glattmuskulären Elektromyogramms der Corpora cavernosa (CC-EMG) mittels Fast-Fourier-Transformation (FFT)

“…Von den drei im menschlichen Körper vorkommenden Muskelarten (Herzmuskulatur, quergestreifte und glatte Muskulatur) wird die elektrische Aktivität der Herzmuskulatur mit dem Elektrokardiogramm (EKG) und die der Skelettmuskulatur mit dem Elektromyogramm (EMG) routinemäßig erfaßt. Elektromyographische Aufzeichnungen glattmuskulärer Zellen wurden unter experimentellen Bedingungen in den vergangenen 20 Jahren an verschiedenen Organsystemen durchgeführt: Ureter [4], Uterus [17], Kolon [11,20], Duodenum [1], Magen [10], Trachea [8], Gallenblase [9] und Gefäße [7]. Eine Messung der elektrischen Aktivität in der glatten Muskulatur hat sich bislang als klinisches Standardverfahren nicht durchsetzen können.…”

Computer-Assisted Evaluation of the Smooth-Muscle Electromyogram of the Corpora cavernosa by Fast Fourier Transformation

“…In clinical routine, the electrical activity of cardiac muscle (ECG) and of striated muscle (EMG) has been registered for decades. Electrical activity of smooth-muscle organs such as ureter [1], uterus [2], colon [3,4], duodenum [5], gaster [6], trachea [7], gall bladder [8] and vessels [9] was registered mainly in a laboratory setting. This smoothmuscle EMG did not have a widespread clinical use since the above-mentioned organs needed surgical exposure Nevertheless, there were conflicting reports on normal and abnormal CC-EMG recordings due to a missing con sensus on the basic principles of the examination itself and the recording parameters.…”