Related Experiment Video
Updated: May 31, 2026

Preparation of Human Myocardial Tissue for Long-Term Cultivation
Published on: June 2, 2022
The inhibitory effect of Ca2+-activated K+ channel activator, BMS on L-type Ca2+ channels in rat ventricular myocytes
Youn Kyoung Son1, Seong Woo Choi, Won-Kyo Jung
1Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 200-701, Republic of Korea.
Aims:
We investigated the effects of BMS-204352 (BMS), a big-conductance calcium-activated potassium (BK(Ca)) channel activator, on L-type Ca(2+) channels.
Main Methods:
Electrophysiological recordings were performed in isolated rat ventricular myocytes. Whole-cell configuration was used.
Key Findings:
BMS caused inhibition of the Ca(2+) current in a dose-dependent manner, with K(d) of 6.00 ± 0.67 μM and a Hill coefficient of 1.33 ± 0.18. BMS did not affect the steady-state activation of L-type Ca(2+) channels. However, for those in steady-state inactivation, BMS shifted the half-maximal potential (V(1/2)) by -11 mV, but the slope value (k) was not altered. Iberiotoxin, inhibitor of membrane BK(Ca) channels and paxilline, inhibitor of mitochondrial BK(Ca) channel did not affect the inhibitory effect of BMS on L-type Ca(2+) channels. Pretreatment with inhibitors of protein kinase A (PKA), protein kinase C (PKC), and protein kinase G (PKG) did not significantly alter the inhibitory effect of BMS on L-type Ca(2+) current. The presence of a selective β-adrenergic receptor agonist, isoproterenol did not affect the inhibitory effect of BMS on L-type Ca(2+) current. Based on these results, we concluded that the inhibition of L-type Ca(2+) channels by BMS is independent of the inhibition of BK(Ca) channels or intracellular signaling pathways.
Significance:
It is important to take BMS-204352 (BMS) effects on L-type Ca(2+) channels into consideration when using BMS as a BK(Ca) channel activator or therapeutic target in ventricular myocytes.
More Related Videos
Related Concept Videos
Antihypertensive Drugs: Action of Calcium Channel Blockers
Antiarrhythmic Drugs: Class IV Agents as Calcium Channel Blockers
Verapamil, a calcium channel blocker, inhibits calcium movement across myocardial cell membranes and vascular smooth muscle. This results in the dilation of coronary and...
Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers
G-Protein Gated Ion Channels
Sensory organs,...
Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...

