Journal of Applied Physiology, Vol 39, Issue 5 868-872, Copyright © 1975 by American Physiological Society
Sodium kinetics in aorta of spontaneously hypertensive rats
J. G. Llaurado and J. A. Madden
Transport rate constants (kij) for Na exchanges in isolated aorta of
normotensive and spontaneously hypertensive rats (SHR) were determined with
the use of 33Na as a tracer and the aid of digital computer simulation. A
three-compartment model consisting of 1) extracellular, 2) intracellular,
and 3) "endointracellular" spaces (compartments) was found to describe
adequately the kinetics of 22Na. Results show that in SHR: I) K01, which is
related to the overall Na outflow from tissue, was increased by 41%; ii)
k12, describing Na movements from intra- to extracellular compartment, was
increased by 67%; iii) k21, representative of Na movements from extra-to
intracellular compartment, was decreased by 39%. These results indicate a
faster turn-over of Na and a relative accumulation or translocation of Na
into the extracellular space in aorta of SHR. The findings are interpreted
in the light of recent reports on the role of Na in contractile response or
reactivity of arteries. A humoral mechanism operative at the arterial wall
level for the development of hypertension is at the arterial wall level for
the development of hypertension is suggested. The main significance of the
methodology employed in this work is that the values found for the kij are
not subject to fluctuations intrinsic to auxiliary indicators of
extracellular space.
