AJP - Heart and Circulatory Physiology, Vol 258, Issue 1 29-H37, Copyright © 1990 by American Physiological Society
Analysis of vasomotion waveform changes during pressure reduction and adenosine application
H. H. Oude Vrielink, D. W. Slaaf, G. J. Tangelder, S. Weijmer-Van Velzen and R. S. Reneman
Department of Physiology, University of Limburg, Maastricht, The Netherlands.
Changes in the vasomotion waveform were studied in transverse arterioles
(TAs) and their first-order side branches (FOSs) in the tenuissimus muscle
of 14 young, anesthetized rabbits during stepwise arterial pressure
reduction and local application of adenosine using intravital video
microscopy. Pressure reduction resulted in a systematic increase in
vasomotion cycle length (CL) and amplitude (A) concomitant with an increase
in effective vascular diameter (Deff) and maximum diameter and a decrease
in blood flow (Q). During adenosine application Deff and maximum diameter
also increased, but CL and A did not change systematically. At moderate
pressure reductions and during adenosine application CL changes were
limited (less than 1.5 s) and nonsystematic, agreeing with an earlier study
(D. W. Slaaf, G. J. Tangelder, H. C. Teirlinck, and R. S. Reneman.
Microvasc. Res. 33: 71-80, 1987). In TAs these changes resulted from
changes in both the dilation and the constriction phase. In FOSs, however,
changes in CL were caused by prolongation of the dilation phase alone. At
greatly reduced pressure levels, the CL increase was more pronounced and in
both TAs and FOSs was caused by plateau formation in the dilation phase.
Stretch of the arteriolar wall does not seem to play a role in control of
the vasomotion waveform. Because the onsets of dilation always occur
synchronously in TAs and FOSs, but the onsets of constriction do not,
vasomotion seems to be a series of rhythmic dilations.
