TY - JOUR
T1 - Inspiratory action of separate external and parasternal intercostal muscle contraction
AU - Budzinska, K.
AU - Supinski, G.
AU - DiMarco, A. F.
PY - 1989
Y1 - 1989
N2 - We have previously shown that electrical stimulation of the thoracic spinal cord produces near maximal activation of the inspiratory intercostal muscles. In the present investigation, we used this technique to evaluate the relative capacity of separate external (EI) and parasternal intercostal (PA) muscle contraction to produce changes in airway pressure and inspired volume. Studies were performed in 23 anesthetized phrenicotomized dogs. Electrical stimuli were applied to the spinal cord after hyperventilation-induced apnea, before and after sequentially severing either the PA or EI muscles from the first through sixth intercostal spaces. During spinal cord stimulation (SCS), measurements were made of inspired volume (ΔV) with the airway open and negative airway pressure (ΔP) during tracheal occlusion. Compared with control values, sectioning of the PA muscles resulted in a 40.9% reduction in ΔP and 35.7% reduction in ΔV during SCS. In other animals, initial sectioning of the EI muscles produced reductions in ΔP and ΔV of 67.4 and 63.0, respectively, during SCS. After subsequent section of the PA muscles, SCS produced only negligible inspired volumes and changes in airway pressure. We conclude that 1) the EI and PA muscles are each capable of generating substantial changes in airway pressure and large inspired volumes and 2) the ventilatory capacity of the EI muscles exceeds that of the PA muscles.
AB - We have previously shown that electrical stimulation of the thoracic spinal cord produces near maximal activation of the inspiratory intercostal muscles. In the present investigation, we used this technique to evaluate the relative capacity of separate external (EI) and parasternal intercostal (PA) muscle contraction to produce changes in airway pressure and inspired volume. Studies were performed in 23 anesthetized phrenicotomized dogs. Electrical stimuli were applied to the spinal cord after hyperventilation-induced apnea, before and after sequentially severing either the PA or EI muscles from the first through sixth intercostal spaces. During spinal cord stimulation (SCS), measurements were made of inspired volume (ΔV) with the airway open and negative airway pressure (ΔP) during tracheal occlusion. Compared with control values, sectioning of the PA muscles resulted in a 40.9% reduction in ΔP and 35.7% reduction in ΔV during SCS. In other animals, initial sectioning of the EI muscles produced reductions in ΔP and ΔV of 67.4 and 63.0, respectively, during SCS. After subsequent section of the PA muscles, SCS produced only negligible inspired volumes and changes in airway pressure. We conclude that 1) the EI and PA muscles are each capable of generating substantial changes in airway pressure and large inspired volumes and 2) the ventilatory capacity of the EI muscles exceeds that of the PA muscles.
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U2 - 10.1152/jappl.1989.67.4.1395
DO - 10.1152/jappl.1989.67.4.1395
M3 - Article
C2 - 2793741
AN - SCOPUS:0024426958
SN - 0161-7567
VL - 67
SP - 1395
EP - 1400
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 4
ER -