Membrane potential measurements in renal afferent and efferent arterioles: actions of angiotensin II.
Am J Physiol
; 273(2 Pt 2): F307-14, 1997 Aug.
Article
em En
| MEDLINE
| ID: mdl-9277592
ABSTRACT
An adaptation of the in vitro perfused hydronephrotic rat kidney model allowing in situ measurement of arteriolar membrane potentials is described. At a renal perfusion pressure of 80 mmHg, resting membrane potentials of interlobular arteries (22 +/- 2 microns) and afferent (14 +/- 1 microns) and efferent arterioles (12 +/- 1 microns) were -40 +/- 2 (n = 8), -40 +/- 1 (n = 45), and -38 +/- 2 mV (n = 22), respectively (P = 0.75). Using a dual-pipette system to stabilize the impalement site, we measured afferent and efferent arteriolar membrane potentials during angiotensin II (ANG II)-induced vasoconstriction. ANG II (0.1 nM) reduced afferent arteriolar diameters from 13 +/- 1 to 8 +/- 1 microns (n = 8, P = 0.005) and membrane potentials from -40 +/- 2 to -29 +/- mV (P = 0.012). ANG II elicited a similar vasoconstriction in efferent arterioles, decreasing diameters from 13 +/- 1 to 8 +/- 1 microns (n = 8, P = 0.004), but failed to elicit a significant depolarization (-39 +/- 2 for control; -36 +/- 3 mV for ANG II; P = 0.27). Our findings thus indicate that resting membrane potentials of pre- and postglomerular arterioles are similar and lie near the threshold activation potential for L-type Ca channels. ANG II-induced vasoconstriction appears to be closely coupled to membrane depolarization in the afferent arteriole, whereas mechanical and electrical responses appear to be dissociated in the efferent arteriole.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Circulação Renal
/
Angiotensina II
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article