AJP - Heart and Circulatory Physiology, Vol 256, Issue 1 32-H40, Copyright © 1989 by American Physiological Society
A rate-sensitive component to the myogenic response is absent from bat wing arterioles
M. J. Davis and P. J. Sikes
Department of Medical Physiology, Texas A&M University, College Station 77843.
The responses of three sequential branching orders of arterioles in the bat
wing to rapid and slow changes in transmural pressure were studied.
Arterial and venous pressures to the wing were elevated simultaneously by
pressurizing a box containing the body of the animal, while the wing was
exposed to atmospheric pressure. Box pressure was elevated from 0 to +48
mmHg at two rates: 24 and 0.6 mmHg/s. During this time, continuous
recordings of hydrostatic pressure and diameter were made in single
arterioles using intravital microscopic techniques. Second-order arterioles
and arcuate arterioles from skin and skeletal muscle constricted in
response to elevated transmural pressure but did not show an enhanced
response to rapid pressure changes. There was a trend for terminal
arterioles to show a transient peak constriction during rapid stretch, but
this response was always associated with a biphasic change in arteriolar
pressure. These results suggest that the transient arteriolar resistance
changes associated with rapid transmural pressure increases in previous
experiments may be primarily a result of transient pressure changes in
small arterioles. We find no evidence that arterioles in this preparation
exhibit a rate-sensitive component to their myogenic response.
