AJP - Heart and Circulatory Physiology, Vol 253, Issue 2 270-H275, Copyright © 1987 by American Physiological Society
Red blood cell catecholamine levels in normotensive and DOCA-salt hypertensive rats
M. Bouvier, L. Farley and J. de Champlain
Under basal conditions in anesthetized rats, significant concentrations of
free norepinephrine (NE), epinephrine (E), and dopamine (DA) were detected
in red blood cell (RBC) lysate. These concentrations were not proportional
to their respective plasma concentrations and thus RBC-to-plasma
concentration ratios were different for each catecholamine (CA). DA was by
far the most concentrated amine inside the RBC. An acute increase in plasma
NE and E levels, induced by hemorrhagic hypotension in normotensive (NT)
rats, did not result in any modification of the RBC CA content. However,
chronic elevation of the NE plasma levels in bilaterally adrenalectomized
rats and in deoxycorticosterone acetate (DOCA)-salt hypertensive rats
(DOCA-salt HT) were associated with increased NE levels in the RBC. In
addition, the large elevation in plasma E concentrations following
hemorrhagic hypotension in DOCA-salt HT rats, as well as the greater plasma
NE response to hypotension in adrenalectomized animals, were accompanied by
increases in the respective RBC amine concentrations. During a steady-state
intravenous infusion of tritiated NE, we observed a slow accumulation of
radioactivity inside the RBC, indicating that CA can enter the RBC from the
plasma. Moreover, catechol methyltransferase activity was measured in the
cytosolic fraction of the RBC of both NT and DOCA-salt HT rats suggesting
that, once inside the RBC, the catecholamines can be metabolized.
