Participation of PKG and PKA-related pathways in the IFN-γ induced modulation of the BKCa channel activity in human cardiac fibroblasts

• Published in: Journal of pharmacological sciences Vol. 141; no. 1; pp. 25 - 31
• Main Authors: Mitrokhin, M.V., Kalsin, V., Kamkina, O., Babkina, I., Zotov, A., Troitskiy, V.A., Mladenov, M.I., Kamkin, G.A.
• Format: Journal Article
• Language: English
• Published: Elsevier 01.09.2019
• ISSN: 1347-8613; 1347-8648
• DOI: 10.1016/j.jphs.2019.08.006

This study was devoted to elucidating the interferon (IFN)-γ-induced signaling pathway and the interaction between protein kinase G (PKG) and protein kinase A (PKA) through large-conductance Ca(2+)-activated K(+) channels in human cardiac fibroblasts. The IK currents were recorded using a whole-cell patch clamp method. A large depolarization (+50 mV) and a high Ca2+ concentration (pCa 6.0) were used in the internal pipette solution to activate only the KCa channels. Iberiotoxin (Ibtx), which selectively inhibits BKCa channels at a concentration of 100 nmol/l, caused a significant reduction of basal IK. Adding IFN-γ in the presence of Ibtx had no effect on IK. Application of the IFN-γ caused a significant reduction in total K+ current amplitude, recorded with a 500 ms depolarizing pulse duration, to +50 mV from a holding potential of −80 mV. We tested the involvement of the sGC/cGMP/PKG signaling pathway by using specific PKG inhibitor KT 5823, potent sGC inhibitor NS 2028, and specific sGC agonist BAY 41-8543. The obtained data confirmed that only sGC participated in the IFN-γ-mediated BKCa channel modulation, which was mediated further by PKA. This study represents first evidence about the participation of the IFN-γ in the mechanisms responsible for BKCa modulation in HCFs. We also believe that this process occurs via negative crosstalk between the PKG- and PKA-associated pathways. Keywords: Human cardiac fibroblasts, IFN-γ, BKCa channels, sGC, PKA