Abstract
Aim: We tested the hypothesis that KV7 channels contribute to basal renal
vascular tone and that they participate in agonist-induced renal vasoconstriction
or vasodilation.
Methods: KV7 channel subtypes in renal arterioles were characterized by
immunofluorescence. Renal blood flow (RBF) was measured using an
ultrasonic flow probe. The isometric tension of rat interlobar arteries was
examined in a wire myograph. Mice afferent arteriolar diameter was
assessed utilizing the perfused juxtamedullary nephron technique.
Results: Immunofluorescence revealed that KV7.4 channels were expressed
in rat afferent arterioles. The KV7 blocker XE991 dose-dependently
increased the isometric tension of rat interlobar arteries and caused a small
(approx. 4.5%) RBF reduction in vivo. Nifedipine abolished these effects.
Likewise, XE991 reduced mouse afferent arteriolar diameter by approx.
5%. The KV7.2–5 stimulator flupirtine dose-dependently relaxed isolated
rat interlobar arteries and increased (approx. 5%) RBF in vivo. The RBF
responses to NE or Ang II administration were not affected by pre-treatment
with XE991 or flupirtine. XE991 pre-treatment caused a minor augmentation
of the acetylcholine-induced increase in RBF, while flupirtine
pre-treatment did not affect this response.
Conclusion: It is concluded that KV7 channels, via nifedipine sensitive
channels, have a role in the regulation of basal renal vascular tone. There
is no indication that KV7 channels have an effect on agonist-induced renal
vasoconstriction while there is a small effect on acetylcholine-induced
vasodilation
Original language | English |
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Journal | Acta Physiologica (Print) |
Volume | 214 |
Issue number | 3 |
Pages (from-to) | 402-414 |
ISSN | 1748-1708 |
DOIs | |
Publication status | Published - 2015 |
Keywords
- Afferent arteriole
- Hyperpolarization
- KCNQ
- Renal hemodynamics
- Renal vascular resistance