Citrulline activates adenosine receptors: New insight into metabolic pathways interaction.

Citrulline is a non-proteinogenic amino acid that forms as by-product in nitric oxide (NO) synthesis from arginine and may act in concert with NO as an independent signaling molecule that involves in the mechanism of vascular smooth muscle vasodilation. In this study we examined the effects of citrulline on pulmonary artery smooth muscles. Experimental design comprised outward potassium currents measurements in enzymatically isolated rat pulmonary artery smooth muscle (PASMc) cells using whole-cell patch clamp technique, isometric contractile force recordings on rat pulmonary artery rings and method of molecular docking simulation.

Oxidative and Nitrous Stress Underlies Vascular Malfunction Induced by Ionizing Radiation and Diabetes.

Oxidative stress results from the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in quantities exceeding the potential activity of the body's antioxidant system and is one of the risk factors for the development of vascular dysfunction in diabetes and exposure to ionizing radiation. Being the secondary products of normal aerobic metabolism in living organisms, ROS and RNS act as signaling molecules that play an important role in the regulation of vital organism functions. Meanwhile, in high concentrations, these compounds are toxic and disrupt various metabolic pathways.

Calcium-dependent modulation of BK channel activity induced by plasmonic gold nanoparticles in pulmonary artery smooth muscle cells and hippocampal neurons.

Aim: Gold nanoparticles are widely used for biomedical applications, but the precise molecular mechanism of their interaction with cellular structures is still unclear. Assuming that intracellular calcium fluctuations associated with surface plasmon-induced calcium entry could modulate the activity of potassium channels, we studied the effect of 5 nm gold nanoparticles on calcium-dependent potassium channels and associated calcium signaling in freshly isolated rat pulmonary artery smooth muscle cells and cultured hippocampal neurons.

Methods: Outward potassium currents were recorded using patch-clamp techniques.

Electrophysiological characterization of the activating action of a novel liposomal nitric oxide carrier on Maxi-K channels in pulmonary artery smooth muscle cells.

The aim of this study was to establish the mechanisms of action of a novel liposomal nitric oxide (NO) carrier on large-conductance Ca-activated channels (BK or Maxi-K) expressed in vascular smooth muscle cells (VSMCs) isolated from the rat main pulmonary artery (MPA). Experimental design comprised of both whole-cell and cell-attached single-channel recordings using the patch-clamp techniques. The liposomal form of NO, Lip(NO), increased whole-cell outward K currents in a dose dependent manner while shifting the activation curve negatively by about 50 mV with respect to unstimulated cells with the EC value of 0.

Hypoxic pulmonary vasoconstriction is lacking in rats with type 1 diabetes.

Hypoxic pulmonary vasoconstriction (HPV) is the most important feature of intact lung circulation that matches local blood perfusion to ventilation. The main goal of this work was to study the effects of diabetes on the development of HPV in rats. The experimental design comprised diabetes mellitus induction by streptozotocin, video-morphometric measurements of the lumen area of intrapulmonary arteries (iPAs) using perfused lung tissue slices and patch-clamp techniques.

C fullerenes selectively inhibit BK but not K channels in pulmonary artery smooth muscle cells.

Possessing unique physical and chemical properties, C fullerenes are arising as a potential nanotechnological tool that can strongly affect various biological processes. Recent molecular modeling studies have shown that C fullerenes can interact with ion channels, but there is lack of data about possible effects of C molecule on ion channels expressed in smooth muscle cells (SMC). Here we show both computationally and experimentally that water-soluble pristine C fullerene strongly inhibits the large conductance Ca-dependent K (BK), but not voltage-gated K (K) channels in pulmonary artery SMC.

Mechanisms of vascular dysfunction evoked by ionizing radiation and possible targets for its pharmacological correction.

Ionizing radiation (IR) leads to a variety of the cardiovascular diseases, including the arterial hypertension. A number of studies have demonstrated that blood vessels represent important target for IR, and the endothelium is one of the most vulnerable components of the vascular wall. IR causes an inhibition of nitric oxide (NO)-mediated endothelium-dependent vasodilatation and generation of reactive oxygen (ROS) and nitrogen (RNS) species trigger this process.

Liposomal quercetin potentiates maxi-K channel openings in smooth muscles and restores its activity after oxidative stress.

The effects of quercetin-loaded liposomes (PCL-Q) and their constituents, that is, free quercetin (Q) and 'empty' phosphatidylcholine vesicles (PCL), on maxi-K channel activity were studied in single mouse ileal myocytes before and after HO-induced oxidative stress. Macroscopic Maxi-K channel currents were recorded using whole-cell patch clamp techniques, while single BK channel currents were recorded in the cell-attached configuration. Bath application of PCL-Q (100 μg/ml of lipid and 3 μg/ml of quercetin) increased single Maxi-K channel activity more than threefold, from 0.

Plasmonic gold nanoparticles possess the ability to open potassium channels in rat thoracic aorta smooth muscles in a remote control manner.

Colloidal gold nanoparticles (AuNPs) of ~5nm core size and Zeta-potential of -35mV, having absorption maximum and plasmon resonance in the range of 510-570nm, were studied as a potential K(+)-channel opener in vascular smooth muscle (SM) cells. Experimental design of the study comprised SM contractile recordings. When externally applied to the organ bath, AuNPs (10(-6)-3×10(-4)M) led to decrease in amplitude of norepinephrine-induced contractions in a concentration-dependent and endothelium-independent manner in SM thoracic aorta, with mean value of pD2 (-log EC50) 4.

Protein kinase C in enhanced vascular tone in diabetes mellitus.

Diabetes mellitus (DM) is a complex syndrome which leads to multiple dysfunctions including vascular disorders. Hyperglycemia is considered to be a key factor responsible for the development of diabetic vascular complications and can mediate their adverse effects through multiple pathways. One of those mechanisms is the activation of protein kinase C (PKC).

PKC-δ isozyme gene silencing restores vascular function in diabetic rat.

Abstract Background: Endothelium and K+ channel functionality in smooth muscle cells (SMCs) regulates vascular function and is exposed to damage in diabetes. The regulatory enzyme protein kinase C (PKC) is known to play a key role in vascular tone regulation in health and disease. In this study, we evaluated the effect of PKC-δ gene silencing using small interfering RNAs (siRNAs) on endothelial dysfunction and acquired potassium channelopathy in vascular SMCs in diabetes.

Correction of vascular hypercontractility in spontaneously hypertensive rats using shRNAs-induced delta protein kinase C gene silencing.

Potassium conductance in vascular smooth muscle (VSM) is known to be altered in arterial hypertension. High level of protein kinase C (PKC) activity is a common feature for hypertension of different genesis. The main goal of this study was to investigate the efficacy of the RNA interference (RNAi) technique targeting PKC delta-isoform gene as a possible pharmacological tool to restore vasodilator potential in spontaneously hypertensive rats (SHR).

Gap junctions support the sustained phase of hypoxic pulmonary vasoconstriction by facilitating calcium sensitization.

Aims: To determine the role of gap junctions (GJs) in hypoxic pulmonary vasoconstriction (HPV).

Methods And Results: Studies were performed in rat isolated intrapulmonary arteries (IPAs) mounted on a myograph and in anaesthetized rats. Hypoxia induced a biphasic HPV response in IPAs preconstricted with prostaglandin F2α (PGF2α, 3 µM) or 20 mM K⁺.

Selective glycolysis blockade in guinea pig pulmonary artery and aorta reverses contractile and electrical responses to acute hypoxia.

The goal of this study was to clarify the mechanisms of hypoxic pulmonary vasoconstriction (HPV) reversal following selective glycolysis blockade and to assess possible contribution of endothelial electrogenesis to this phenomenon as a trigger mechanism. We compared smooth muscle (SM) contractility and endothelial cell (EC) membrane potential (MP) during acute hypoxia before and after glycolysis blockade. MPs were recorded from the endothelium of guinea pig pulmonary artery (GPPA) and thoracic aorta (GPTA) using the patch-clamp technique.

The BK(Ca) channels deficiency as a possible reason for radiation-induced vascular hypercontractility.

It is likely that large-conductance Ca²⁺-activated K⁺ (BK(Ca)) channels channelopathy tightly involved in vascular malfunctions and arterial hypertension development. In the present study, we compared the results of siRNAs-induced α-BK(Ca) gene silencing and vascular abnormalities produced by whole-body ionized irradiation in rats. The experimental design comprised RT-PCR and patch clamp technique, thoracic aorta smooth muscle (SM) contractile recordings and arterial blood pressure (BP) measurements on the 30th day after whole body irradiation (6Gy) and following siRNAs KCNMA1 gene silencing in vivo.

Protein kinase C-dependent inhibition of BK(Ca) current in rat aorta smooth muscle cells following gamma-irradiation.

Purpose: The aim of this study was to estimate the effects of non-fatal whole-body gamma-irradiation on outward potassium plasma membrane conductivity in rat vascular smooth muscle cells (VSMC), and to identify underlying mechanisms.

Materials And Methods: Rats were exposed to a 6 Gy dose irradiation from a cobalt(60) source. Whole-cell potassium current was measured in freshly isolated rat aorta smooth muscle cells using standard patch-clamp technique.

Electrophysiological and contractile evidence of the ability of human mesenchymal stromal cells to correct vascular malfunction in rats after ionizing irradiation.

The effect of intravenous administration of human mesenchymal stromal stem cells (hMSC) has been evaluated by means of large-conductance calcium-dependent potassium channel (BK(Ca)) activity measurements in thoracic aorta smooth muscle cells (SMC) obtained from non-fatal whole-body irradiated rats, using the patch clamp technique in whole-cell modification, and the standard acetylcholine (ACh) test to evaluate functional endothelium integrity using SM contractile recordings. Myofilament calcium sensitivity was estimated using simultaneous contractile recordings versus [Ca(2+)](i). Arterial blood was measured in intact and irradiated rats before and after hMSC administration.

Quercetin-filled phosphatidylcholine liposomes restore abnormalities in rat thoracic aorta BK(Ca) channel function following ionizing irradiation.

The goal of the present study was to investigate the effects of quercetin-filled phosphatidylcholine liposomes (PCL-Q) on the currents carried by large conductance Ca(2+)-dependent K(+) channels (BK(Ca)) in rat thoracic aorta following non-fatal whole-body ionizing irradiation. Using patch-clamp technique, it is found that the outward K(+) currents of isolated smooth muscle cells (SMCs) stimulated by depolarizing voltage steps were sensitive to BK(Ca) inhibitor, paxilline, and this kind of outward K(+) currents in SMCs from irradiated animals demonstrated a significant decrease in amplitude. Radiation-induced BK(Ca) suppression was evident 9 days post-irradiation and progressively increased over 30 days of experimental period.

Functional and molecular consequences of ionizing irradiation on large conductance Ca2+-activated K+ channels in rat aortic smooth muscle cells.

Aims: The goal of this study was to evaluate the influence of gamma-irradiation on Ca(2+)-activated K(+) channel (BK(Ca)) function and expression in rat thoracic aorta.

Main Methods: Aortic cells or tissues were studied by the measurement of force versus [Ca(2+)](i), patch-clamp technique, and RT-PCR.

Key Findings: Stimulation of smooth muscle cells with depolarizing voltage steps showed expression of outward K(+) currents.

Ionizing non-fatal whole-body irradiation inhibits Ca2+-dependent K+ channels in endothelial cells of rat coronary artery: possible contribution to depression of endothelium-dependent vascular relaxation.

Purpose: The goal of this study was to evaluate the influence of ionizing irradiation on large conductance Ca2+-dependent potassium (BKCa) channels in rat coronary endothelial cells.

Materials And Methods: Rats were exposed to a 6 Gy dose from a cobalt60 source. Experimental design of this study comprised recording of contractile force using isolated rat aortic rings and whole-cell patch clamp techniques to study whole-cell potassium currents in isolated rat coronary artery endothelial cells.

Ionizing radiation alters myofilament calcium sensitivity in vascular smooth muscle: potential role of protein kinase C.

Radiation exposure increases vascular responsiveness, and this change involves endothelial damage, as well as direct effects on vascular smooth muscle. In this study, we tested the hypothesis that myofilament Ca(2+) sensitivity in vascular smooth muscle is increased from single whole body gamma irradiation (6 Gy). We measured contractile responses from intact and permeabilized rat thoracic aortic rings combined with cytosolic Ca(2+) ([Ca(2+)](i)) measurements.

Mechanisms of endothelial dysfunction after ionized radiation: selective impairment of the nitric oxide component of endothelium-dependent vasodilation.

(1) Gamma radiation impairs vascular function, leading to the depression of endothelium-dependent vasodilatation. Loss of the nitric oxide (NO) pathway has been implicated, but little is known about radiation effects on other endothelial mediators. (2) This study investigated the mechanisms of endothelial dysfunction in rabbits subjected to whole-body irradiation from a cobalt(60) source.