Interaction of sympathetic nervous system and renin angiotensin system in renal haemodynamics of renal failure, hypertensive and renal failure hypertensive rats
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Date
2009
Authors
Basri, Fathihah
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Abstract
a 1-adrenoceptors and angiotensin type 1 (AT1) receptor subtypes play a key role in
the regulation of renal haemodynamics. Sympathetic overactivity is the common
pathogenesis that aggravates renal failure into further complications. This study
discusses the functional role of a1-adrenoceptors and AT 1 receptor in mediating the
vasoconstriction of renal resistance vessels in renal haemodynamics of renal failure,
hypertension and combination of both pathological states emphasizing on the
interaction between sympathetic nervous system (SNS) and renin-angiotensin system
(RAS). Normotensive WKY and hypertensive SHR were utilized. Cisplatin (5 mglkg
i.p) was used to induce renal failure. Non-renal failure and renal failure WKY and
SHR were grouped according to their pre-treament which were control, denervation
by 6-hydroxydopamine (60HDA), losartan (10 mglkg/day) (LOS) and a combination
oflosartan and 60HDA (60HDALOS). Losartan was given orally for 7 days prior to
the acute study. Body weight, water intake, urine output, urine and plasma sodium,
creatinine clearance, fractional excretion of sodium and kidney index were measured.
In acute study, the animals were anesthetized (60 mglkg i.p. sodium pentobarbi~one)
for blood pressure and renal blood flow (RBF) measurements. Reductions in RBF to
electrical stimulation of renal nerve and intrarenal administration of noradrenaline,
phenylephrine, methoxamine and angiotensin II were determined. Data were
recorded using a computerized data acquisition system and expressed as mean ±
s.e.m and analysed by 2-way ANOV A followed by Bonferronni post-hoc test with a
significance level at 5%. Significant reductions in the body weight and water intake,
increased urine output and fractional excretion of sodium as well as a marked
decrease in the creatinine clearance were observed in the renal failure rats. From the
renal vasoconstrictor responses, an intact renal nerve is very important in regulation
of renal haemodynamics. It seems that functionality of alB I am adrenoceptors in the
positive crosstalk with AT 1 receptor was greatly influenced by sympathectomy and
losartan. Furthermore blockade of RAS produced a positive interaction with SNS.
This study further supported that the fact there is exaggerated sympathetic activity in
diseased animals and its severity increases in multiple diseased states. Moreover,
under the influence of renal failure and hypertensive conditions, there was a shift in
functional contributions of a 1 adrenoceptors subtype in enhanced sympathetic
conditions. Collectively it is suggested that there was a positive crosstalk relationship
between a 1- adrenoceptors and AT1 receptors, and this is greatly influenced by the
pathological conditions of renal failure and hypertension.
Description
Keywords
Sympathetic nervous , Failure hypertensive