Electromyography of the diaphragm in rabbits

Abstract

A series of 25 adult male rabbits had multiple clip electrodes implanted in their diaphragms at open operation. Following postoperative recovery, the wires from these electrodes were connected to an electromyograph and records were made along with spirometry under normal physiological conditions. The spirometric tracings show four, rather than two, distinct respiratory phases. Just prior to the inspiratory and expiratory phases, a brief but appreciable phase exists during which no air moves into or out of the lungs. These static phases are called pre-inspiratory and pre-expiratory. Diaphragmatic activity continues throughout the respiratory cycle and surveys of the individual recordings reveal beyond question that, although there are many minor variations in degrees of activity between various muscular slips of the same rabbit's diaphragm (even adjacent slips), no obvious general pattern of difference exists. There is no electromyographic peculiarity of behavior in either the lumbar, costal, and sternal parts or for the right and left sides of the rabbit's diaphragm.