Left ventricular volumetric conductance catheter for rats .
Ito, Haruo, Miyako Takaki, Hiroki Yamaguchi, Hideo Tachibana, and
Hiroyuki Suga.
Department of Physiology II, Okayama University Medical School,
Shikata-cho, Okayama 700, JAPAN
APStracts 2:0428H, 1995.
Left ventricular (LV) volume (V) is an essential parameter for
assessment of the cardiac pump function. Measurement of LVV in situ
by a conductance catheter method has been widely used in dogs and
humans, but not yet in small experimental animals such as rats. We
instituted a miniaturized six-electrode conductance catheter (3F) for
rat LVV measurement and its signal processing apparatus. We compared
stroke volumes simultaneously measured with this conductance catheter
introduced into the LV through the apex and an electromagnetic flow
probe placed on the ascending aorta during gradual decreases in LVV
by an inferior vena caval occlusion. A high and linear correlation
(r=0.982) was obtained between these differently measured stroke
volumes pooled from 6 rats. In another group of 3 rats, LV pressure
was simultaneously measured with a 3F catheter-tip micromanometer
introduced into the LV through the apex. We obtained the slope of the
end-systolic pressure-volume (P-V) relation (Emax) by a gradual
ascending aortic occlusion. After administration of propranolol, Emax
obviously decreased with no change in volume intercept (Vo) of the P
-V relation. The conductance volumetry proved to be useful in rats.
Received 12 June 1995; accepted in final form 12 September 1995.
APS Manuscript Number H535-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95