Tuning electrical conduction along endothelial tubes of resistance arteries through Ca(2+)-activated K(+) channels.
Circ Res
; 110(10): 1311-21, 2012 May 11.
Article
en En
| MEDLINE
| ID: mdl-22492531
ABSTRACT
RATIONALE Electrical conduction through gap junction channels between endothelial cells of resistance vessels is integral to blood flow control. Small and intermediate-conductance Ca(2+)-activated K(+) channels (SK(Ca)/IK(Ca)) initiate electrical signals in endothelial cells, but it is unknown whether SK(Ca)/IK(Ca) activation alters signal transmission along the endothelium. OBJECTIVE:
We tested the hypothesis that SK(Ca)/IK(Ca) activity regulates electrical conduction along the endothelium of resistance vessels. METHODS ANDRESULTS:
Freshly isolated endothelial cell tubes (60 µm wide; 1-3 mm long; cell length, ≈35 µm) from mouse skeletal muscle feed (superior epigastric) arteries were studied using dual intracellular microelectrodes. Current was injected (±0.1-3 nA) at site 1 while recording membrane potential (V(m)) at site 2 (separation distance=50-2000 µm). SK(Ca)/IK(Ca) activation (NS309, 1 µmol/L) reduced the change in V(m) along endothelial cell tubes by ≥50% and shortened the electrical length constant (λ) from 1380 to 850 µm (P<0.05) while intercellular dye transfer (propidium iodide) was maintained. Activating SK(Ca)/IK(Ca) with acetylcholine or SKA-31 also reduced electrical conduction. These effects of SK(Ca)/IK(Ca) activation persisted when hyperpolarization (>30 mV) was prevented with 60 mmol/L [K(+)](o). Conversely, blocking SK(Ca)/IK(Ca) (apamin+charybdotoxin) depolarized cells by ≈10 mV and enhanced electrical conduction (ie, changes in V(m)) by ≈30% (P<0.05).CONCLUSIONS:
These findings illustrate a novel role for SK(Ca)/IK(Ca) activity in tuning electrical conduction along the endothelium of resistance vessels by governing signal dissipation through changes in membrane resistance. Voltage-insensitive ion channels can thereby tune intercellular electrical signaling independent from gap junction channels.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Resistencia Vascular
/
Endotelio Vascular
/
Uniones Comunicantes
/
Arterias Epigástricas
/
Canales de Potasio Calcio-Activados
Límite:
Animals
Idioma:
En
Revista:
Circ Res
Año:
2012
Tipo del documento:
Article
País de afiliación:
Estados Unidos