Journal of Applied Physiology, Vol 65, Issue 4 1506-1513, Copyright © 1988 by American Physiological Society
Effect of amrinone on diaphragm blood flow
R. J. Bundy, J. S. Arnold, A. F. DiMarco, F. Hussein and G. S. Supinski
Cleveland Metropolitan General Hospital, Department of Medicine, Case Western Reserve University, Ohio 44106.
The purpose of the present study was to examine the effect of amrinone, a
drug known to augment cardiac output and dilate peripheral vascular beds,
on diaphragm blood flow. Studies were performed on 12 anesthetized
mechanically ventilated dogs in which strips of left costal diaphragm were
developed in situ. Strip blood flow was assessed with a drop counter
attached to a catheter tied into the phrenic veins' draining strips. Strip
tension was measured with an isometric force transducer. Amrinone was
administered as an intravenous bolus of 2 mg/kg followed by a continuous
infusion of 25 micrograms.kg-1.min-1. Amrinone increased cardiac output and
resting diaphragm blood flow [from 1.8 +/- 0.1 to 3.2 +/- 3 (SE) l/min and
from 13 +/- 2 to 29 +/- 6 (SE) ml.100 g-1.min-1, respectively, P less than
0.001 for both comparisons]. Amrinone also increased blood flow during
periods of rhythmic contraction (tension time indexes of 0.1-0.4, P less
than 0.05 for comparisons of flow with and without amrinone at each tension
time index) and increased the magnitude of the postcontraction hyperemia (P
less than 0.02 for comparisons of hyperemic flow with and without amrinone
at tension time indexes of 0.3 and 0.4). Graded occlusion of the inferior
vena cava produced reductions in arterial pressure, cardiac output, and
diaphragm blood flow both before and after amrinone. Both cardiac output
and diaphragm blood flow were greater after amrinone, however, at all
levels of blood pressure examined. These findings indicate that amrinone
can override diaphragm vasoregulatory systems and augment diaphragm blood
flow.(ABSTRACT TRUNCATED AT 250 WORDS)
