Nephrology Dialysis Transplantation, Vol 12, Issue 5 939-944, Copyright © 1997 by Oxford University Press
N Esforzado Armengol, A Cases Amenos, M Bono Illa, J Gaya Bertran, J Calls Ginesta and F Rivera Fillat
Background. The pathophysiology of chronic
hypertension (CH) in uraemia is not elucidated. The possible role of
autonomic nervous system dysfunction and adrenoceptor alterations in the
pathophysiology of CH in uraemia was evaluated in this study.
Methods. Seventeen hypotensive haemodialysis (HD)
patients, 17 normotensive HD patients, and 17 control subjects were
studied. We evaluated the integrity of the baroreflex arc (Valsalva
manoeuvre), the parasympathetic efferent pathway ('deep-breathing test')
and the sympathetic efferent pathway ('hand-grip test'). We also evaluated
platelet &agr;2-adrenoceptor and lymphocyte {beta}2-adrenoceptor
densities (radioligand binding assay), and {beta}2-adrenoceptor response
(intracellular cAMP generation after isoproterenol stimulation in
lymphocytes). Results. Responses to the Valsalva
manoeuvre and the deep-breathing test were altered in all HD patients
(P <0.05). Valsalva ratio was lower in
hypotensive patients than in normotensive patients (P
<0.01), whereas the pressor response to the hand-grip test was
reduced only in hypotensive HD patients (P
<0.01). In haemodialysed patients, basal mean blood pressure (MBP)
correlated with MBP increases during the hand-grip exercise
(r = 0.59, P <0.01).
Plasma catecholamine levels were elevated in both groups of patients
(P <0.025). Plasma adrenaline levels were
higher in hypotensive HD patients than in normotensive patients
(P <0.05). &agr;2- and
{beta}2-adrenoceptor densities and {beta}2-adrenoceptor response were
reduced in hypotensive patients (P <0.05
vs normotensive patients). MBP correlated with
&agr;2-adrenoceptor (r = 0.46,
P <0.01) and {beta}2-adrenoceptor
(r = 0.43, P <0.025)
densities in HD patients. Conclusions. Normotensive
haemodialysed patients have increased plasma catecholamine levels with
preserved &agr;2- and {beta}2-adrenoceptor numbers, as well as
{beta}2-adrenoceptor responses. In hypotensive patients, plasma
adrenaline levels were even higher; the increased plasma catecholamine
levels induced an &agr;2- and {beta}2-adrenoceptor downregulation.
This downregulation may play a role in the reduced cardiovascular responses
to adrenergic stimuli reported in hypotensive HD patients.
Keywords: autonomic nervous system; adrenoceptors;
chronic ypertension; chronic renal failure; haemodialysis
ORIGINAL ARTICLES
Autonomic nervous system and adrenergic receptors in chronic hypotensive haemodialysis patients
Nephrology and Hormonology Units, Hospital Clinic I Provincial, Barcelona, Spain; Correspondence to A Cases Amenos, Nephrology Unit, Hospital Clinic I Provincial, C/Villarroel 170, 08036 Barcelona, Spain
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