Regulation of ventilatory muscle blood flow.
Hussain, Sabah N. A.
Critical Care and Respiratory Divisions, Department of Medicine,
Royal Victoria Hospital, McGill University, Montreal, Quebec,
Canada
APStracts 3:0233A, 1996.
The ventilatory muscles perform various functions such as ventilation
of the lungs, postural stabilization and expulsive maneuvers
(coughing, etc.). They are classified in functional terms as:
inspiratory muscles which include the diaphragm, parasternal
intercostal, external intercostal, scalene and sternocleidomastoid;
and expiratory muscles which include the abdominal muscles, internal
intercostal and triangularis sterni. The ventilatory muscles require
high energy phosphate compounds such as adenosine triphosphate (ATP)
to fuel the biochemical and physical processes of contraction and
relaxation. Maintaining adequate intracellular concentrations of
these compounds depends upon adequate intracellular substrate levels
and delivery of these substrates by arterial blood flow. In addition
to the delivery of substrates, blood flow influences muscle function
through the removal of metabolic byproducts which, if accumulated,
could exert negative effects on several excitatory and contractile
processes. Skeletal muscle substrate utilization is also dependent
upon the ability to extract substrates from arterial blood which, in
turn, is accomplished by increasing the total number of perfused
capillaries. It follows that matching perfusion to metabolic demands
is critical for the maintenance of normal muscle contractile
function. IN this article, I reviewed the factors which influence
ventilatory muscle blood flow. Major emphasis is placed on the
diaphragm because a large number of published reports deal with
diaphragmatic blood flow. The second reason for focusing on the
diaphragm is because it is the largest and most important inspiratory
muscle.
Received 1 January 1996; accepted in final form 30 January 1996.
APS Manuscript Number A379-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96