TY - JOUR
T1 - High efficacy by GAL-021
T2 - A known intravenous peripheral chemoreceptor modulator that suppresses BKca-channel activity and inhibits Ik(m) or Ih
AU - Lu, Te Ling
AU - Gao, Zi Han
AU - Li, Shih Wei
AU - Wu, Sheng Nan
N1 - Funding Information:
Funding: The research work detailed in this paper is partly supported by grants from the National Cheng Kung University (D107-F2519, D108-F2507, and NCKUH-10709001), from the Ministry of Science and Technology (MOST-108-2314-B-006-094), and from China Medical University (CMU101-ASIA-07), Taiwan, all of which are through a contract awarded to S.N. Wu.
Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2020/2
Y1 - 2020/2
N2 - GAL-021 has recently been developed as a novel breathing control modulator. However, modifications of ionic currents produced by this agent remain uncertain, although its efficacy in suppressing the activity of big-conductance Ca2+-activated K+ (BKCa) channels has been reported. In pituitary tumor (GH3) cells, we found that the presence of GAL-021 decreased the amplitude of macroscopic Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an effective IC50 of 2.33 μM. GAL-021-mediated reduction of IK(Ca) was reversed by subsequent application of verteporfin or ionomycin; however, it was not by that of diazoxide. In inside-out current recordings, the addition of GAL-021 to the bath markedly decreased the open-state probability of BKCa channels. This agent also resulted in a rightward shift in voltage dependence of the activation curve of BKCa channels; however, neither the gating charge of the curve nor single-channel conductance of the channel was changed. There was an evident lengthening of the mean closed time of BKCa channels in the presence of GAL-021, with no change in mean open time. The GAL-021 addition also suppressed M-type K+ current with an effective IC50 of 3.75 μM; however, its presence did not alter the amplitude of erg-mediated K+ current, or mildly suppressed delayed-rectifier K+ current. GAL-021 at a concentration of 30 μM could also suppress hyperpolarization-activated cationic current. In HEK293T cells expressing α-hSlo, the addition of GAL-021 was also able to suppress the BKCa-channel open probabilities, and GAL-021-mediated suppression of BKCa-channel activity was attenuated by further addition of BMS-191011. Collectively, the GAL-021 effects presented herein do not exclusively act on BKCa channels and these modifications on ionic currents exert significant influence on the functional activities of electrically excitable cells occurring in vivo.
AB - GAL-021 has recently been developed as a novel breathing control modulator. However, modifications of ionic currents produced by this agent remain uncertain, although its efficacy in suppressing the activity of big-conductance Ca2+-activated K+ (BKCa) channels has been reported. In pituitary tumor (GH3) cells, we found that the presence of GAL-021 decreased the amplitude of macroscopic Ca2+-activated K+ current (IK(Ca)) in a concentration-dependent manner with an effective IC50 of 2.33 μM. GAL-021-mediated reduction of IK(Ca) was reversed by subsequent application of verteporfin or ionomycin; however, it was not by that of diazoxide. In inside-out current recordings, the addition of GAL-021 to the bath markedly decreased the open-state probability of BKCa channels. This agent also resulted in a rightward shift in voltage dependence of the activation curve of BKCa channels; however, neither the gating charge of the curve nor single-channel conductance of the channel was changed. There was an evident lengthening of the mean closed time of BKCa channels in the presence of GAL-021, with no change in mean open time. The GAL-021 addition also suppressed M-type K+ current with an effective IC50 of 3.75 μM; however, its presence did not alter the amplitude of erg-mediated K+ current, or mildly suppressed delayed-rectifier K+ current. GAL-021 at a concentration of 30 μM could also suppress hyperpolarization-activated cationic current. In HEK293T cells expressing α-hSlo, the addition of GAL-021 was also able to suppress the BKCa-channel open probabilities, and GAL-021-mediated suppression of BKCa-channel activity was attenuated by further addition of BMS-191011. Collectively, the GAL-021 effects presented herein do not exclusively act on BKCa channels and these modifications on ionic currents exert significant influence on the functional activities of electrically excitable cells occurring in vivo.
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U2 - 10.3390/biom10020188
DO - 10.3390/biom10020188
M3 - Article
C2 - 31991782
AN - SCOPUS:85078688476
SN - 2218-273X
VL - 10
JO - Biomolecules
JF - Biomolecules
IS - 2
M1 - 188
ER -