Renal responses to acute reflex activation of renal sympathetic nerve activity and renal denervation in secondary hypertension.
Am J Physiol Regul Integr Comp Physiol
; 293(3): R1247-56, 2007 Sep.
Article
em En
| MEDLINE
| ID: mdl-17626124
ABSTRACT
We tested whether the responsiveness of the kidney to basal renal sympathetic nerve activity (RSNA) or hypoxia-induced reflex increases in RSNA, is enhanced in angiotensin-dependent hypertension in rabbits. Mean arterial pressure, measured in conscious rabbits, was similarly increased (+16 +/- 3 mmHg) 4 wk after clipping the left (n = 6) or right (n = 5) renal artery or commencing a subcutaneous ANG II infusion (n = 9) but was not increased after sham surgery (n = 10). Under pentobarbital sodium anesthesia, reflex increases in RSNA (51 +/- 7%) and whole body norepinephrine spillover (90 +/- 17%), and the reductions in glomerular filtration rate (-27 +/- 5%), urine flow (-43 +/- 7%), sodium excretion (-40 +/- 7%), and renal cortical perfusion (-7 +/- 3%) produced by hypoxia were similar in normotensive and hypertensive groups. Hypoxia-induced increases in renal norepinephrine spillover tended to be less in hypertensive (1.1 +/- 0.5 ng/min) than normotensive (3.7 +/- 1.2 ng/min) rabbits, but basal overflow of endogenous and exogenous dihydroxyphenolglycol was greater. Renal plasma renin activity (PRA) overflow increased less in hypertensive (22 +/- 29 ng/min) than normotensive rabbits (253 +/- 88 ng/min) during hypoxia. Acute renal denervation did not alter renal hemodynamics or excretory function but reduced renal PRA overflow. Renal vascular and excretory responses to reflex increases in RSNA induced by hypoxia are relatively normal in angiotensin-dependent hypertension, possibly due to the combined effects of reduced neural norepinephrine release and increased postjunctional reactivity. In contrast, neurally mediated renin release is attenuated. These findings do not support the hypothesis that enhanced neural control of renal function contributes to maintenance of hypertension associated with activation of the renin-angiotensin system.
Buscar no Google
Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Reflexo
/
Sistema Nervoso Simpático
/
Hipertensão Renal
/
Rim
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol Regul Integr Comp Physiol
Assunto da revista:
FISIOLOGIA
Ano de publicação:
2007
Tipo de documento:
Article
País de afiliação:
Austrália