Functional, electrophysiological and molecular docking analysis of the modulation of Ca_v1.2 channels in rat vascular myocytes by murrayafoline A

Abstract

BACKGROUND AND PURPOSEThe carbazole alkaloid murrayafoline A (MuA) enhances contractility and the Ca 2+ currents carried by the Ca v 1.2 channels [I Ca1.2 ] of rat cardiomyocytes. As only few drugs stimulate I Ca1.2 , this study was designed to analyse the effects of MuA on vascular Ca v 1.2 channels. EXPERIMENTAL APPROACHVascular activity was assessed on rat aorta rings mounted in organ baths. Ca v 1.2 Ba 2+ current [I Ba1.2 ] was recorded in single rat aorta and tail artery myocytes by the patch-clamp technique. Docking at a 3D model of the rat, α 1c central pore subunit of the Ca v 1.2 channel was simulated in silico. KEY RESULTSIn rat aorta rings MuA, at concentrations ≤14.2 μM, increased 30 mM K + -induced tone and shifted the concentration-response curve to K + to the left. Conversely, at concentrations >14.2 μM, it relaxed high K + depolarized rings and antagonized Bay K 8644-induced contraction. In single myocytes, MuA stimulated I Ba1.2 in a concentration-dependent, bell-shaped manner; stimulation was stable, incompletely reversible upon drug washout and accompanied by a leftward shift of the voltage-dependent activation curve. MuA docked at the α 1C subunit central pore differently from nifedipine and Bay K 8644, although apparently interacting with the same amino acids of the pocket. Neither Bay K 8644-induced stimulation nor nifedipine-induced block of I Ba1.2 was modified by MuA. CONCLUSIONS AND IMPLICATIONSMurrayafoline A is a naturally occurring vasoactive agent able to modulate Ca v 1.2 channels and dock at the α 1C subunit central pore in a manner that differed from that of dihydropyridines.

Open‐channel blocking action of volatile anaesthetics desflurane and sevoflurane on human voltage‐gated Kv1.5 channel

“…The amino acids with side chain atoms located within 4.5 Å of the docked anaesthetics were regarded as having a potential contact. To evaluate the contribution of individual amino acids within hK v 1.5 channels towards anaesthetic interaction, we conducted in silico alanine scanning mutagenesis using Residue Scan module of MOE (Liu, Peng, Zhou, Zhang, & Zhang, 2018; Saponara et al, 2016), where a specific amino acid, predicted to have potential contact with anaesthetics, was mutated to alanine. The binding free energy (Δ G ) was calculated before and after the mutation using GBVI/WSA dG (Generalized‐Born Volume Integral/Weighted Surface area) scoring function (Corbeil et al, 2012), and the difference in binding free energies (ΔΔ G ) was determined as follows: where Δ G mutant is the binding free energy for anaesthetic to the mutated hK v 1.5 channel and Δ G WT is the binding free energy for anaesthetic to WT hK v 1.5 channel.…”

Extra Virgin Olive Oil Extracts of Indigenous Southern Tuscany Cultivar Act as Anti-Inflammatory and Vasorelaxant Nutraceuticals

“…The thoracic aorta was gently cleaned of adipose and connective tissues and cut into 3-mm-wide rings. These were mounted in organ baths between two parallel L-shaped stainless steel hooks, one fixed in place and the other connected to an isometric transducer [39]. Rings were allowed to equilibrate for 60 min in KHS (composition in mM: 118 NaCl, 4.75 KCl, 1.19 KH 2 PO 4 , 1.19 MgSO 4 , 25 NaHCO 3 , 11.5 glucose, 2.5 CaCl 2 , gassed with a 95% O 2 -5% CO 2 gas mixture to create a pH of 7.4) under a passive tension of 1 g. During this equilibration period, the solution was changed every 15 min.…”

Antihypertensive, cardio- and neuro-protective effects of Tenebrio molitor (Coleoptera: Tenebrionidae) defatted larvae in spontaneously hypertensive rats

“…Aorta ring mechanical activity. Rings were prepared as previously described [16]. Relaxation of phenylephrine-contracted rings to either acetylcholine or sodium nitroprusside was taken as an index of endothelial function and muscle sensitivity to NO, respectively (more details in S6 File).…”