Tissue spaces in rat heart, liver and skeletal muscle in vivo.
Cieslar, Julie, Ming-Ta Huangand Geoffrey P. Dobson.
Department of Physiology and Pharmacology, James Cook University of
North Queensland, Townsville, Queensland, Australia 4811 and
1Department of Biochemistry, Chang Gung College of Medicine and
Technology, Kwei-san, Tao-yuan, Taiwan, ROC
APStracts 5:0226R, 1998.
Tissue spaces were determined in rat heart, liver and skeletal muscle
in vivo using isotopically labelled [14C]-inulin. Tracer was injected
into the jugular vein of pentobarbitol anaesthetised male Sprague
-Dawley rats. After a 30 minute equilibration period a blood sample
was taken and heart, liver and gastrocnemius muscle excised and
immediately freeze-clamped at liquid nitrogen temperatures. The
extracellular inulin space (ml/g wet wt tissue +/- SE) was 0.209 +/-
0.006 (n=13) for heart; 0.203 +/- 0.080 (n=7) for liver; and 0.124
+/- 0.006 (n=8) for skeletal muscle. Total tissue water (ml/g wet wt
tissue) was 0.791 +/- 0.005 (n=9) for heart; 0.732 +/- 0.002 (n=9)
for liver and 0.755 +/- 0.005 (n=10) for skeletal muscle. Expressed
as a percentage of total tissue water (%TTW), the intracellular space
was 73.6 % for heart, 72.2% for liver and 83.7 % for skeletal muscle.
Using 2,3 DPG as a vascular marker, the interstitial space was
calculated by subtracting the counts in tissue due to whole blood
from total tissue counts and dividing by plasma counts. The
interstitial space was 18.8 %, 22.4 % and 14.5 % TTW with
accompanying plasma spaces of 7.7 %, 5.3 % and 1.8 % for heart, liver
and gastrocnemius respectively. This study provides a quantitiative
assessment of water distribution in tissues of non-nephrectomised
rats which has applications for calculation of tissue ion and
metabolite concentrations, gradients and fluxes under different
normal and pathophysiological conditions.
Received 31 March 1998; accepted in final form 19 June 1998.
APS Manuscript Number R198-8.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 30 July 1998