AJP - Heart and Circulatory Physiology, Vol 251, Issue 4 815-H823, Copyright © 1986 by American Physiological Society
Mechanical and inotropic reserve in conscious dogs with left ventricular hypertrophy
A. M. Fujii, S. F. Vatner, J. Serur, A. Als and I. Mirsky
We studied the left ventricular (LV) responses to infusions of
norepinephrine and prenalterol, a specific beta 1-adrenergic receptor
agonist, in conscious, chronically instrumented adult dogs with severe LV
hypertrophy. The goal of this study was to determine the extent of
compensation induced by LV hypertrophy in an animal model in which the
pressure overload was gradually increased, as occurs in human pathological
states. One to 2 yr after banding the ascending aorta of puppies, six dogs
with severe LV hypertrophy (LV free-wall weight-to-body weight ratio 7.0
+/- 0.4 g/kg), and nine sham-operated littermates (LV free-wall
weight-to-body weight ratio 4.0 +/- 0.2 g/kg) were studied. The dogs were
instrumented with ultrasonic dimension crystals (to measure LV short-axis
diameter and wall thickness), miniature LV pressure transducers, and LV and
aortic catheters. In the control dogs norepinephrine (0.4 micrograms X kg-1
X min-1) increased LV systolic/diastolic pressure from 121 +/- 2/9 +/- 1 to
177 +/- 9/20 +/- 2 mmHg, mean arterial pressure from 97 +/- 2 to 143 +/- 9
mmHg, LV dP/dt from 3,363 +/- 123 to 5,174 +/- 343 mmHg/s, and mean
systolic wall stress from 194 +/- 14 to 299 +/- 22 g/cm2, while mean
velocity of circumferential fiber shortening (Vcf), (dD/dt/D)max, and heart
rate did not change from base line. In dogs with LV hypertrophy
norepinephrine increased LV pressure from 224 +/- 16/11 +/- 1 to 305 +/-
22/19 +/- 1 mmHg, mean arterial pressure from 90 +/- 2 to 132 +/- 4 mmHg,
LV dP/dt from 3,246 +/- 156 to 5,619 +/- 345 mmHg/s, and mean systolic wall
stress from 224 +/- 11 to 307 +/- 24 g/cm2.(ABSTRACT TRUNCATED AT 250
WORDS)
