AJP - Heart and Circulatory Physiology, Vol 235, Issue 6 728-H735, Copyright © 1978 by American Physiological Society
Inhibitory effect of hypertonic mannitol on vasoconstrictor and vasodilator responses of isolated coronary arteries
V. S. Krishnamurty, H. R. Adams, G. H. Templeton and J. T. Willerson
The effect of hypertonic mannitol on pressor responses to vasoactive agents
was studied in isolated canine coronary arteries perfused with physiologic
salt solution at a constant flow. When perfusion pressure was increased
with 60 mM KCl, mannitol (50 mosM) consistently caused a decrease in
perfusion pressure that lasted for at least 1 h. Withdrawal of mannitol
from the perfusion media was associated with a vasoconstrictor response
that was not prevented by alpha- or beta-adrenoceptor blockade or by the
presence of either nitroglycerin or norepinephrine. Hypertonic mannitol
also reduced the responsiveness of the isolated smooth muscle preparations
to several different mechanistically unrelated vasodilator agents. The
mechanism(s) responsible for the paradoxical ability of hypertonic mannitol
to reduce vascular responsiveness to both vasoconstrictor and vasodilator
interventions in isolated canine coronary arteries is not known, but future
studies should be directed at elucidating it as well as determining whether
similar phenomena occur in vivo.
