N-Salicyloyltryptamine, an N-Benzoyltryptamine Analogue, Induces Vasorelaxation through Activation of the NO/sGC Pathway and Reduction of Calcium Influx.

Benzoyltryptamine analogues act as neuroprotective and spasmolytic agents on smooth muscles. In this study, we investigated the ability of N-salicyloyltryptamine (STP) to produce vasorelaxation and determined its underlying mechanisms of action. Isolated rat mesenteric arteries with and without functional endothelium were studied in an isometric contraction system in the presence or absence of pharmacological inhibitors. Amperometric experiments were used to measure the nitric oxide (NO) levels in CD31+ cells using flow cytometry. GH3 cells were used to measure Ca2+ currents using the whole cell patch clamp technique. STP caused endothelium-dependent and -independent relaxation in mesenteric rings. The endothelial-dependent relaxations in response to STP were markedly reduced by L-NAME (endothelial NO synthase-eNOS-inhibitor), jHydroxocobalamin (NO scavenger, 30 µM) and ODQ (soluble Guanylyl Cyclase-sGC-inhibitor, 10 µM), but were not affected by the inhibition of the formation of vasoactive prostanoids. These results were reinforced by the increased NO levels observed in the amperometric experiments with freshly dispersed CD31+ cells. The endothelium-independent effect appeared to involve the inhibition of voltage-gated Ca2+ channels, due to the inhibition of the concentration-response Ca2+ curves in depolarizing solution, the increased relaxation in rings that were pre-incubated with high extracellular KCl (80 mM), and the inhibition of macroscopic Ca2+ currents. The present findings show that the activation of the NO/sGC/cGMP pathway and the inhibition of gated-voltage Ca2+ channels are the mechanisms underlying the effect of STP on mesenteric arteries.

Aging: Molecular Pathways and Implications on the Cardiovascular System.

The world's population over 60 years is growing rapidly, reaching 22% of the global population in the next decades. Despite the increase in global longevity, individual healthspan needs to follow this growth. Several diseases have their prevalence increased by age, such as cardiovascular diseases, the leading cause of morbidity and mortality worldwide. Understanding the aging biology mechanisms is fundamental to the pursuit of cardiovascular health. In this way, aging is characterized by a gradual decline in physiological functions, involving the increased number in senescent cells into the body. Several pathways lead to senescence, including oxidative stress and persistent inflammation, as well as energy failure such as mitochondrial dysfunction and deregulated autophagy, being ROS, AMPK, SIRTs, mTOR, IGF-1, and p53 key regulators of the metabolic control, connecting aging to the pathways which drive towards diseases. In addition, senescence can be induced by cellular replication, which resulted from telomere shortening. Taken together, it is possible to draw a common pathway unifying aging to cardiovascular diseases, and the central point of this process, senescence, can be the target for new therapies, which may result in the healthspan matching the lifespan.

EPA:DHA 6:1 prevents angiotensin II-induced hypertension and endothelial dysfunction in rats: role of NADPH oxidase- and COX-derived oxidative stress.

Eicosapentaenoic acid:docosahexaenoic acid (EPA:DHA) 6:1, an omega-3 polyunsaturated fatty acid formulation, has been shown to induce a sustained formation of endothelial nitric oxide (NO) synthase-derived NO, a major vasoprotective factor. This study examined whether chronic intake of EPA:DHA 6:1 prevents hypertension and endothelial dysfunction induced by angiotensin II (Ang II) in rats. Male Wister rats received orally corn oil or EPA:DHA 6:1 (500 mg kg-1 per day) before chronic infusion of Ang II (0.4 mg kg-1 per day). Systolic blood pressure was determined by tail cuff sphingomanometry, vascular reactivity using a myograph, oxidative stress using dihydroethidium and protein expression by immunofluorescence and western blot analysis. Ang II-induced hypertension was associated with reduced acetylcholine-induced relaxations of secondary branch mesenteric artery rings affecting the endothelium-dependent hyperpolarization (EDH)- and the NO-mediated relaxations, both of which were improved by the NADPH oxidase inhibitor VAS-2870. The Ang II treatment induced also endothelium-dependent contractile responses (EDCFs), which were abolished by the cyclooxygenase (COX) inhibitor indomethacin. An increased level of vascular oxidative stress and expression of NADPH oxidase subunits (p47phox and p22phox), COX-1 and COX-2, endothelial NO synthase and Ang II type 1 receptors were observed in the Ang II group, whereas SKCa and connexin 37 were downregulated. Intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction by improving both the NO- and EDH-mediated relaxations, and by reducing EDCFs and the expression of target proteins. The present findings indicate that chronic intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction in rats, most likely by preventing NADPH oxidase- and COX-derived oxidative stress.

Replicative senescence promotes prothrombotic responses in endothelial cells: Role of NADPH oxidase- and cyclooxygenase-derived oxidative stress.

Endothelial senescence has been suggested to promote endothelial dysfunction in age-related vascular disorders. This study evaluated the prothrombotic properties of senescent endothelial cells (ECs) and the underlying mechanism. Serial passaging from passage (P)1 to P4 (replicative senescence) of porcine coronary artery ECs, or treatment of P1 ECs with the endothelial nitric oxide synthase (eNOS) inhibitor L-NAME (premature senescence) induced acquisition of markers of senescence including increased senescence-associated-ß-galactosidase (SA-ß-gal) activity and p53, p21, p16 expression. Approximately 55% of P3 cells were senescent with a high level oxidative stress, and decreased eNOS-derived nitric oxide (NO) formation associated with increased expression of NADPH oxidase subunits (gp91phox, p47phox), cyclooxygenase (COX)-2 but not COX-1, and a decreased eNOS expression leading to a reduced ability of ECs to inhibit platelet aggregation. P3 cells also presented increased expression and activity of tissue factor (TF), a key initiator of the coagulation cascade. Treatment of senesecent cells with a NADPH oxidase inhibitor (VAS-2870) or by a COX inhibitor (indomethacin) reduced oxidative stress, decreased TF activity and expression, and reduced the expression of gp91phox, p47phox and COX-2 and restored the ability of ECs to inhibit effectively platelet aggregation. Thus, replicative endothelial senescence promotes a prothrombotic response involving the down-regulation of the protective NO pathway and the upregulation of the NADPH oxidase- and COXs-dependent oxidative stress pathway promoting TF expression and activity.

The Redox-sensitive Induction of the Local Angiotensin System Promotes Both Premature and Replicative Endothelial Senescence: Preventive Effect of a Standardized Crataegus Extract.

Endothelial senescence, characterized by an irreversible cell cycle arrest, oxidative stress, and downregulation of endothelial nitric oxide synthase (eNOS), has been shown to promote endothelial dysfunction leading to the development of age-related vascular disorders. This study has assessed the possibility that the local angiotensin system promotes endothelial senescence in coronary artery endothelial cells and also the protective effect of the Crataegus extract WS1442, a quantified hawthorn extract. Serial passaging from P1 to P4 (replicative senescence) and treatment of P1 endothelial cells with the eNOS inhibitor L-NAME (premature senescence) promoted acquisition of markers of senescence, enhanced ROS formation, decreased eNOS expression, and upregulation of angiotensin-converting enzyme (ACE) and AT1 receptors. Increased SA-ß-gal activity and the upregulation of ACE and AT1R in senescent cells were prevented by antioxidants, an ACE inhibitor, and by an AT1 receptor blocker. WS1442 prevented SA-ß-gal activity, the downregulation of eNOS, and oxidative stress in P3 cells. These findings indicate that the impairment of eNOS-derived nitric oxide formation favors a pro-oxidant response triggering the local angiotensin system, which, in turn, promotes endothelial senescence. Such a sequence of events can be effectively inhibited by a standardized polyphenol-rich extract mainly by targeting the oxidative stress.

Participation of the TRP channel in the cardiovascular effects induced by carvacrol in normotensive rat.

Carvacrol has been described as an agonist/antagonist of different transient receptor potential (TRP) channels and voltage-dependent calcium channels (Cavs). The aim of this study was to evaluate the role of Cav and TRP channels following carvacrol stimulation. Initially, in mesenteric artery rings carvacrol relaxed phenylephrine-induced contractions. Furthermore, carvacrol inhibited contraction elicited by CaCl2 in depolarizing nominally without Ca2+ medium and antagonized the contractions induced by S(-)-Bay K 8644 and inhibited Ca2+ currents indicating the inhibition of Ca2+ influx through L-type Cav. Additionally, carvacrol antagonized the contractions induced by CaCl2 in the presence of nifedipine/Cyclopiazonic acid/phenylephrine or nifedipine/Cyclopiazonic acid/KCl 60, suggesting a possible inhibition of calcium influx by store operated channels (SOCs), receptor operated channels (ROCs) and/or TRP channels. Interestingly, among the TRP channel blockers used, the effect induced by carvacrol was attenuated by Mg2+ and potentiated by La3+ and Gd3+, suggesting that TRP channels are involved in relaxation induced by carvacrol. Monoterpene also induced hypotension and bradycardia in non-anesthetized normotensive rats and negative inotropic and chronotropic effects. In conclusion, these results suggest that the hypotensive effect of carvacrol is probably due to bradycardia and a peripheral vasodilatation that involves, at least, the inhibition of the Ca2+ influx through Cav and TRP channels.