The Resveratrol-induced Relaxation of Cholecystokinin Octapeptide- or KCl-induced Tension in Male Guinea Pig Gallbladder Strips Is Mediated Through L-type Ca2+Channels

Resveratrol Relaxes Human Gastric Smooth Muscles Through High Conductance Calcium-Activated Potassium Channel in a Nitric Oxide-independent Manner

Resveratrol, as a polyphenolic compound that can be isolated from plants, and also a component of red wine has broad beneficial pharmacological properties. The aim was to investigate the role of nitric oxide and potassium channels in resveratrol-induced relaxation of human gastric smooth muscle. Gastric tissues were obtained from patients who underwent sleeve gastrectomy for severe obesity (n = 10 aged 21–48; BMI 48.21 ± 1.14). The mechanical activity from the muscle strips was detected under isometric conditions as the response to increasing concentrations of resveratrol before and after different pharmacological treatments. Resveratrol caused an observable, dose-dependent gastric muscle relaxation. The maximal response caused by the highest concentration of resveratrol was 83.49 ± 2.85% (p < 0.0001) of the control. Preincubation with L-NNA, L-NAME, or ODQ did not prevent the resveratrol-induced relaxation. Apamin, glibenclamide, 4AP or tamoxifen, did not inhibit the relaxing effect of resveratrol, as well. In turn, blocking BK_Ca by TEA, iberiotoxin, or charybdotoxin resulted in inhibition of resveratrol-induced relaxation (91.08 ± 2.07, p < 0.05; 95.60 ± 1.52, p < 0.01 and 89.58 ± 1.98, p < 0.05, respectively). This study provides the first observation that the relaxant effects of resveratrol in human gastric muscle strips occur directly through BK_Ca channels and independently of nitric oxide signaling pathways. Furthermore, there is considerable potential for further extensive clinical studies with resveratrol as an effective new drug or health supplement to treat gastrointestinal dyspepsia and other gastric hypermotility disorders.

Quercetin relaxes human gastric smooth muscles directly through ATP-sensitive potassium channels and not depending on the nitric oxide pathway

BACKGROUND

Quercetin has recently become a remarkably popular subject of research due to its broad beneficial pharmacological properties. The goal of our study was to observe its effects on contractility of human gastric smooth muscles in reference to the NO pathway and direct influence of potassium channels.

METHODS

Tissues were obtained from patients undergoing sleeve gastrectomy due to morbid obesity (n = 10 aged 24-56; BMI 47.16 ± 1.84). The following parameters were evaluated in the recordings: area under the curve (AUC), average baseline muscle tone, and relative change in muscle contraction.

KEY RESULTS

Quercetin induced noticeable, dose-dependent relaxation of the carbachol treated gastric strips. The substantial effect was noted at concentrations higher than 10^-7  mol/L and maximal at 10^-4  mol/L (81.82 ± 3.32%; n = 10; p < 0.0001) of the control. Neither NOS blockers nor guanylyl cyclase blockers had inhibitory effects on the relaxation of strips induced by examined polyphenol. Glibenclamide inhibited the relaxing effect of quercetin, significant at concentrations higher than 5⋅10^-5  mol/L. Preincubation with charybdotoxin or apamin extended the relaxing effect of quercetin (from 10^-6  mol/L). Tamoxifen, in turn, significantly increased muscle relaxation at all quercetin concentrations.

CONCLUSIONS & INFERENCES

In conclusion, the current study was the first to show that quercetin-induced relaxation of human gastric smooth muscle occurs directly through K⁺_ATP channels and independently to NO pathways. The present results suggest that quercetin is a potential nutraceutical in the treatment of functional gastrointestinal dyspepsia and other minor gastric muscle motility disturbance.

Resveratrol's Impact on Vascular Smooth Muscle Cells Hyporeactivity: The Role of Rho-Kinase Inhibition

Resveratrol (3,5,4′-trihydroxystilbene) is a chemical compound belonging to the group of polyphenols and flavonoids. The aim of the present study was to determine the influence of resveratrol application along with certain modulating factors, such as 8Br-cGMP-activator of cGMP-dependent protein kinases, HA-1077-Rho-kinase inhibitor, and Bay K8644-calcium channel agonist, on VMSCs constriction triggered by phenylephrine. Resveratrol at a dose of 10 mg/kg/24 h administered for 4 weeks reduced the reactivity of the arteries to the pressure action of catecholamines. Tests performed after four weeks of resveratrol administration showed that 8Br-cGMP at the concentrations of 0.01 mM/l and 0.1 mM/l intensifies this effect. Simultaneous resveratrol and Bay K8644 administration led to a significant decrease in contractility compared to the vessels collected from animals (Res−). This effect was dependent on the concentration of Bay K8644. Resveratrol seems to be counteractive against Bay K8644 by blocking L-type calcium channels. As the concentration of HA-1077 increased, there was a marked hyporeactivity of the vessels to the pressure effects of phenylephrine. The results indicate synergy between resveratrol and Rho-kinase inhibition.

Beneficial Effects of Resveratrol Administration-Focus on Potential Biochemical Mechanisms in Cardiovascular Conditions

Resveratrol (RV) is a natural non-flavonoid polyphenol and phytoalexin produced by a number of plants such as peanuts, grapes, red wine and berries. Numerous in vitro studies have shown promising results of resveratrol usage as antioxidant, antiplatelet or anti-inflammatory agent. Beneficial effects of resveratrol activity probably result from its ability to purify the body from ROS (reactive oxygen species), inhibition of COX (cyclooxygenase) and activation of many anti-inflammatory pathways. Administration of the polyphenol has a potential to slow down the development of CVD (cardiovascular disease) by influencing on certain risk factors such as development of diabetes or atherosclerosis. Resveratrol induced an increase in Sirtuin-1 level, which by disrupting the TLR4/NF-κB/STAT signal cascade (toll-like receptor 4/nuclear factor κ-light-chain enhancer of activated B cells/signal transducer and activator of transcription) reduces production of cytokines in activated microglia. Resveratrol caused an attenuation of macrophage/mast cell-derived pro-inflammatory factors such as PAF (platelet-activating factor), TNF-α (tumour necrosis factor-α and histamine. Endothelial and anti-oxidative effect of resveratrol may contribute to better outcomes in stroke management. By increasing BDNF (brain-derived neurotrophic factor) serum concentration and inducing NOS-3 (nitric oxide synthase-3) activity resveratrol may have possible therapeutical effects on cognitive impairments and dementias especially in those characterized by defective cerebrovascular blood flow.

Bi-directional regulation of acupuncture on extrahepatic biliary system: An approach in guinea pigs

Clinically, acupuncture affects the motility of the extrahepatic biliary tract, but the underlining mechanisms are still unknown. We applied manual acupuncture (MA) and electrical acupuncture (EA) separately at acupoints Tianshu (ST25), Qimen (LR14), Yanglingquan (GB34), and Yidan (CO11) in forty guinea pigs (4 groups) with or without atropinization under anesthesia while Sphincter of Oddi (SO) myoelectric activities and gallbladder pressure were monitored. In both MA and EA groups, stimulation at ST25 or LR14 significantly increased the frequency and amplitude of SO myoelectrical activities and simultaneously decreased the gallbladder pressure as compared to the pre-MA and pre-EA (P < 0.05). On the contrary, stimulation at GB34 or CO11 significantly decreased SO myoelectricity and increased the gallbladder pressure (P < 0.05). Pretreatment with atropine could abolish the effect of stimulation at acupoints ST25, GB34 and LR14 (P > 0.05), although significant myoelectricity increases were still inducible with MA or EA stimulation at CO11 (P < 0.05). In summary, acupuncture has bi-directional effects to gallbladder pressure and SO function, which probably due to autonomic reflex and somatovisceral interactions.

Mechanism of resveratrol-induced relaxation in the human gallbladder

BACKGROUND

Resveratrol is a polyphenolic compound extracted from plants and is also a constituent of red wine. Resveratrol produces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Although resveratrol has been reported to cause relaxation of the guinea pig gallbladder, limited data are available about the effect of resveratrol on the gallbladder smooth muscle in humans. The purpose of this study was to investigate the relaxation effects of resveratrol in human gallbladder muscle strips.

METHODS

We studied the relaxant effects of resveratrol in human gallbladder. In addition, we also investigated mechanism of resveratrol-induced relaxation in human gallbladder by tetraethylammonium (a non-selective potassium channels blocker), iberiotoxin (an inhibitor of large conductance calcium-activated potassium channel), glibenclamide (an ATP-sensitive potassium channel blocker), charybdotoxin (an inhibitor of large conductance calcium-activated potassium channels and slowly inactivating voltage-gated potassium channels), apamine (a selective inhibitor of the small conductance calcium-activated potassium channel), KT 5720 (a cAMP-dependent protein kinase A inhibitor), KT 5823 (a cGMP-dependent protein kinase G inhibitor), NG-Nitro-L-arginine (a competitive inhibitor of nitric oxide synthase), tetrodotoxin (a selective neuronal Na⁺ channel blocker), and ω-conotoxin GVIA (a selective neuronal Ca²⁺ channel blocker).

RESULTS

The present study showed that resveratrol has relaxant effects in human gallbladder muscle strips. In addition, we found that resveratrol-induced relaxation in human gallbladder is associated with nitric oxide, ATP-sensitive potassium channel, and large conductance calcium-activated potassium channel pathways.

CONCLUSIONS

This study provides the first evidence concerning the relaxant effects of resveratrol in human gallbladder muscle strips. Furthermore, these results demonstrate that resveratrol is a potential new drug or health supplement in the treatment of biliary colic.

Anti-atherogenic properties of resveratrol: 4-week resveratrol administration associated with serum concentrations of SIRT1, adiponectin, S100A8/A9 and VSMCs contractility in a rat model

Resveratrol (3, 4', 5-trihydroxy-trans-stilbene) is a natural, non-flavonoid polyphenol that exerts protective properties against atherosclerosis-associated endothelial dysfunction and senescence. The present study aimed to assess the influence of resveratrol on vascular contractility and molecular factors including sirtuin-1 (SIRT1), adiponectin and calprotectin (S100A8/A9) that are considered to be important elements of atherogenesis. A total of 17 male rats were divided into a control and treatment group and administered resveratrol or a placebo. Pharmacometrics were performed on an isolated and perfused tail artery. Serum SIRT1, adiponectin and S100A8/A9 levels were quantified using an ELISA assay. The level of SIRT1 in the control and treatment groups at time 0 was 4.26 and 4.45 ng/ml, respectively. SIRT1 in the control and treatment groups following 2 weeks of treatment was 4.59 and 6.86 ng/ml, respectively (P<0.05) and following 4 weeks of treatment was 4.15 and 6.38 ng/ml, respectively (P<0.05). The level of adiponectin in the control and treatment groups at time 0 was 1.24 and 1.21 ng/ml, respectively. Following 2 weeks of treatment, the level of adiponectin in the control and treatment groups was 1.22 and 1.2 ng/ml, respectively (P>0.05) and following 4 weeks of treatment was 1.26 and 1.58 ng/ml, respectively (P<0.05). The S100A8/A9 level in control and treatment groups at time 0 was 0.39 and 0.33 ng/ml, respectively. The level of S100A8/A9 in control and treatment groups following 2 weeks of treatment was 0.37 and 0.35 ng/ml, respectively (P>0.05) and following 4 weeks of treatment was 0.34 and 0.32 ng/ml, respectively (P>0.05). EC₅₀ values obtained for phenylephrine in resveratrol-pretreated arteries were significantly higher than controls in the presence and absence of A7-hydrochloride (P<0.05). The results of the present study indicate a significant increase in the concentration of SIRT1 and adiponectin in the resveratrol-pretreated group (P<0.05). S100A8/A9 serum concentrations remained unchanged. Reactivity of resistant arteries was significantly reduced for resveratrol-pretreated vessels and this effect was partially independent of phosphodiesterase (PDE1). Additionally, there was a synergistic interaction observed between resveratrol and the PDE1 inhibitor.

Resveratrol Increases Serum BDNF Concentrations and Reduces Vascular Smooth Muscle Cells Contractility via a NOS-3-Independent Mechanism

Resveratrol is a polyphenol that presents both antineuroinflammatory properties and the ability to interact with NOS-3, what contributes to vasorelaxation. Brain-derived neurotrophic factor (BNDF), a molecule associated with neuroprotection in many neurodegenerative disorders, is considered as an important element of maintaining stable cerebral blood flow. Vascular smooth muscle cells (VSMCs) are considered to be an important element in the pathogenesis of neurodegeneration and a potential preventative target by agents which reduce the contractility of the vessels. Our main objectives were to define the relationship between serum and long-term oral resveratrol administration in the rat model, as well as to assess the effect of resveratrol on phenylephrine- (PHE-) induced contraction of vascular smooth muscle cells (VSMCs). Moreover, we attempt to define the dependence of contraction mechanisms on endothelial NO synthase. Experiments were performed on Wistar rats (n = 17) pretreated with resveratrol (4 weeks; 10 mg/kg p.o.) or placebo. Serum BDNF levels were quantified after 2 and 4 weeks of treatment with ELISA. Contraction force was measured on isolated and perfused tail arteries as the increase of perfusion pressure with a constant flow. Values of serum BNDF in week 0 were 1.18 ± 0.12 ng/mL (treated) and 1.17 ± 0.13 ng/mL (control) (p = ns). After 2 weeks of treatment, BDNF in the treatment group was higher than in controls, 1.52 ± 0.23 ng/mL and 1.24 ± 0.13 ng/mL, respectively. (p = 0.02) Following 4 weeks of treatment, BDNF values were higher in the resveratrol group compared to control 1.64 ± 0.31 ng/mL and 1.32 ± 0.26 ng/mL, respectively (p = 0.031). EC₅₀ values obtained for PHE in resveratrol pretreated arteries were significantly higher than controls (5.33 ± 1.7 × 10⁻⁷M/L versus 4.53 ± 1.2 × 10⁻⁸M/L, p < 0.05). These results show a significant increase in BDNF concentration in the resveratrol pretreated group. The reactivity of resistant arteries was significantly reduced for resveratrol pretreated vessels and this effect was partially NOS-3 independent.