Abstract
Background and Purpose The calcium-activated potassium channel K Ca3.1 is expressed in the vascular endothelium where its activation causes endothelial hyperpolarization and initiates endothelium-derived hyperpolarization (EDH)-dependent dilatation. Here, we investigated whether pharmacological activation of KCa3.1 dilates skeletal muscle arterioles and whether myoendothelial gap junctions formed by connexin40 (Cx40) are required for EDH-type dilatations and pressure depressor responses in vivo. Experimental Approach We performed intravital microscopy in the cremaster muscle microcirculation and blood pressure telemetry in Cx40-deficient mice. Key Results In wild-type mice, the KCa3.1-activator SKA-31 induced pronounced concentration-dependent arteriolar EDH-type dilatations, amounting to ∼40% of maximal dilatation, and enhanced the effects of ACh. These responses were absent in mice devoid of KCa3.1 channels. In contrast, SKA-31-induced dilatations were not attenuated in mice with endothelial cells deficient in Cx40 (Cx40fl/fl:Tie2-Cre). In isolated endothelial cell clusters, SKA-31 induced hyperpolarizations of similar magnitudes (by ∼38 mV) in Cx40fl/fl:Tie2-Cre, ubiquitous Cx40-deficient mice (Cx40 -/-) and controls (Cx40fl/fl), which were reversed by the specific KCa3.1-blocker TRAM-34. In normotensive wild-type and Cx40fl/fl:Tie2-Cre as well as in hypertensive Cx40-/- animals, i.p. injections of SKA-31 (30 and 100 mg·kg-1) decreased arterial pressure by ∼32 mmHg in all genotypes. The depressor response to 100 mg·kg-1 SKA-31 was associated with a decrease in heart rate. Conclusions and Implications We conclude that endothelial hyperpolarization evoked by pharmacological activation of KCa3.1 channels induces EDH-type arteriolar dilatations that are independent of endothelial Cx40 and Cx40-containing myoendothelial gap junctions. As SKA-31 reduced blood pressure in hypertensive Cx40-deficient mice, KCa3.1 activators may be useful drugs for severe treatment-resistant hypertension.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 293-303 |
| Number of pages | 11 |
| Journal | British Journal of Pharmacology |
| Volume | 170 |
| Issue number | 2 |
| DOIs | |
| State | Published - Sep 2013 |
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Keywords
- 2-d]thiazol-2-ylamine)
- Ca -activated K channel
- endothelium-derived hyperpolarizing factor
- gap junction
- hypertension
- microcirculation
- myoendothelial coupling
- SKA-31 (naphtho[1
ASJC Scopus subject areas
- Pharmacology
Cite this
Activation of KCa3.1 by SKA-31 induces arteriolar dilatation and lowers blood pressure in normo- and hypertensive connexin40-deficient mice. / Radtke, Josephine; Schmidt, Kjestine; Wulff, Heike; Köhler, Ralf; De Wit, Cor.
In: British Journal of Pharmacology, Vol. 170, No. 2, 09.2013, p. 293-303.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Activation of KCa3.1 by SKA-31 induces arteriolar dilatation and lowers blood pressure in normo- and hypertensive connexin40-deficient mice
AU - Radtke, Josephine
AU - Schmidt, Kjestine
AU - Wulff, Heike
AU - Köhler, Ralf
AU - De Wit, Cor
PY - 2013/9
Y1 - 2013/9
N2 - Background and Purpose The calcium-activated potassium channel K Ca3.1 is expressed in the vascular endothelium where its activation causes endothelial hyperpolarization and initiates endothelium-derived hyperpolarization (EDH)-dependent dilatation. Here, we investigated whether pharmacological activation of KCa3.1 dilates skeletal muscle arterioles and whether myoendothelial gap junctions formed by connexin40 (Cx40) are required for EDH-type dilatations and pressure depressor responses in vivo. Experimental Approach We performed intravital microscopy in the cremaster muscle microcirculation and blood pressure telemetry in Cx40-deficient mice. Key Results In wild-type mice, the KCa3.1-activator SKA-31 induced pronounced concentration-dependent arteriolar EDH-type dilatations, amounting to ∼40% of maximal dilatation, and enhanced the effects of ACh. These responses were absent in mice devoid of KCa3.1 channels. In contrast, SKA-31-induced dilatations were not attenuated in mice with endothelial cells deficient in Cx40 (Cx40fl/fl:Tie2-Cre). In isolated endothelial cell clusters, SKA-31 induced hyperpolarizations of similar magnitudes (by ∼38 mV) in Cx40fl/fl:Tie2-Cre, ubiquitous Cx40-deficient mice (Cx40 -/-) and controls (Cx40fl/fl), which were reversed by the specific KCa3.1-blocker TRAM-34. In normotensive wild-type and Cx40fl/fl:Tie2-Cre as well as in hypertensive Cx40-/- animals, i.p. injections of SKA-31 (30 and 100 mg·kg-1) decreased arterial pressure by ∼32 mmHg in all genotypes. The depressor response to 100 mg·kg-1 SKA-31 was associated with a decrease in heart rate. Conclusions and Implications We conclude that endothelial hyperpolarization evoked by pharmacological activation of KCa3.1 channels induces EDH-type arteriolar dilatations that are independent of endothelial Cx40 and Cx40-containing myoendothelial gap junctions. As SKA-31 reduced blood pressure in hypertensive Cx40-deficient mice, KCa3.1 activators may be useful drugs for severe treatment-resistant hypertension.
AB - Background and Purpose The calcium-activated potassium channel K Ca3.1 is expressed in the vascular endothelium where its activation causes endothelial hyperpolarization and initiates endothelium-derived hyperpolarization (EDH)-dependent dilatation. Here, we investigated whether pharmacological activation of KCa3.1 dilates skeletal muscle arterioles and whether myoendothelial gap junctions formed by connexin40 (Cx40) are required for EDH-type dilatations and pressure depressor responses in vivo. Experimental Approach We performed intravital microscopy in the cremaster muscle microcirculation and blood pressure telemetry in Cx40-deficient mice. Key Results In wild-type mice, the KCa3.1-activator SKA-31 induced pronounced concentration-dependent arteriolar EDH-type dilatations, amounting to ∼40% of maximal dilatation, and enhanced the effects of ACh. These responses were absent in mice devoid of KCa3.1 channels. In contrast, SKA-31-induced dilatations were not attenuated in mice with endothelial cells deficient in Cx40 (Cx40fl/fl:Tie2-Cre). In isolated endothelial cell clusters, SKA-31 induced hyperpolarizations of similar magnitudes (by ∼38 mV) in Cx40fl/fl:Tie2-Cre, ubiquitous Cx40-deficient mice (Cx40 -/-) and controls (Cx40fl/fl), which were reversed by the specific KCa3.1-blocker TRAM-34. In normotensive wild-type and Cx40fl/fl:Tie2-Cre as well as in hypertensive Cx40-/- animals, i.p. injections of SKA-31 (30 and 100 mg·kg-1) decreased arterial pressure by ∼32 mmHg in all genotypes. The depressor response to 100 mg·kg-1 SKA-31 was associated with a decrease in heart rate. Conclusions and Implications We conclude that endothelial hyperpolarization evoked by pharmacological activation of KCa3.1 channels induces EDH-type arteriolar dilatations that are independent of endothelial Cx40 and Cx40-containing myoendothelial gap junctions. As SKA-31 reduced blood pressure in hypertensive Cx40-deficient mice, KCa3.1 activators may be useful drugs for severe treatment-resistant hypertension.
KW - 2-d]thiazol-2-ylamine)
KW - Ca -activated K channel
KW - endothelium-derived hyperpolarizing factor
KW - gap junction
KW - hypertension
KW - microcirculation
KW - myoendothelial coupling
KW - SKA-31 (naphtho[1
UR - http://www.scopus.com/inward/record.url?scp=84883260008&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84883260008&partnerID=8YFLogxK
U2 - 10.1111/bph.12267
DO - 10.1111/bph.12267
M3 - Article
C2 - 23734697
AN - SCOPUS:84883260008
VL - 170
SP - 293
EP - 303
JO - British Journal of Pharmacology
JF - British Journal of Pharmacology
SN - 0007-1188
IS - 2
ER -