Journal of Applied Physiology, Vol 73, Issue 4 1614-1618, Copyright © 1992 by American Physiological Society
Diaphragmatic microcirculation during halothane and isoflurane exposure in pentobarbital-anesthetized rats
A. Leon, J. Boczkowski, B. Dureuil, E. Vicaut, M. Aubier and J. M. Desmonts
Department d'Anesthesiologie, Hopital Bichat, Paris, France.
We investigated the effects of halothane and isoflurane on diaphragmatic
microcirculation in pentobarbital-anesthetized rats by in vivo video
microscopy. After a baseline period, rats were randomly allocated into
three groups according to administration of 0.5, 0.75, and 1 minimal
alveolar concentration (MAC) of either halothane (group Hal, n = 16),
isoflurane (group Iso, n = 14), or no halogenated agent (group C, n = 20)
in three succeeding steps of 15 min. Mean arterial blood pressure (MAP),
arteriolar diameters, and functional capillary density were analyzed in the
last 3 min of each step. MAP remained unchanged in group C but decreased in
a dose-dependent manner in both halogenated receiving groups. MAP was
significantly lower in rats breathing Hal compared with those breathing
Iso. Arterioles were classified in second (A2, n = 39), third (A3, n = 24),
and fourth (A4, n = 30) order according to their relative location in the
network. No changes in A2 and A3 diameters were noted in either group. A4
diameters remained unchanged in groups C and Iso, whereas a significant
reduction was found in group Hal at 0.75 and 1 MAC exposure (P < 0.05
compared with baseline and with groups C and Iso, respectively). During Iso
exposure, functional capillary density was not significantly different when
compared with baseline and group C, whereas in group Hal it decreased
significantly at 0.5, 0.75, and 1 MAC, amounting to 61.1 +/- 9, 30.7 +/-
10.3, and 22.8 +/- 6.3%, respectively, of baseline (P < 0.01 vs.
baseline and P < 0.05 vs. groups Iso and C for 0.75 and 1 MAC).(ABSTRACT
TRUNCATED AT 250 WORDS)
