Efferent renal sympathetic nerve stimulation in vivo. Effects on regional renal haemodynamics in the Wistar rat, studied by laser-Doppler technique.
Acta Physiol Scand
; 154(3): 387-94, 1995 Jul.
Article
em En
| MEDLINE
| ID: mdl-7572236
ABSTRACT
Intrarenal blood flow regulation probably affects long-term blood pressure homeostasis. We have previously shown that 5 Hz renal sympathetic stimulation inhibits a humoral renal depressor mechanism, otherwise activated when increasing perfusion pressure to an isolated kidney in a cross-circulation set-up. This inhibition was suggested to occur as a result of a reduction of renomedullary blood flow. Little is known about nervous blood flow regulation within the medulla. Therefore in this study, total renal (RBF), cortical (CBF) and papillary (PBF) blood flows were separately measured by ultrasonic and laser-Doppler techniques in Wistar rats during graded renal sympathetic stimulations. Periods of 15 min stimulation at 0.5, 2 and 5 Hz were performed in random order. RBF decreased at 0.5 Hz by 1%, at 2 Hz by 16% (P < 0.001) and at 5 Hz by 49% (P < 0.001). In a similar fashion (r = 0.73, P < 0.001), CBF decreased by 1%, 10% (P < 0.001) and 37% (P < 0.001), respectively. By contrast, PBF increased by 2% at 0.5 Hz and 4% at 2 Hz, while it decreased at 5 Hz, by 4% (P < 0.05, compared with 2 Hz). It seems therefore, that superficial renocortical and total renal blood flows are closely regulated by renal sympathetic nerves with increasing vasoconstriction at higher frequencies, while medullary blood flow, on the other hand, seems to be under strong local control, tending to offset neurogenic flow restrictions.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Circulação Renal
/
Sistema Nervoso Simpático
/
Rim
/
Neurônios Eferentes
Limite:
Animals
Idioma:
En
Revista:
Acta Physiol Scand
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
Suécia
País de publicação:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
/
UK
/
UNITED KINGDOM