Angiotensin II constricts mouse iliac arteries: possible mechanism for aortic aneurysms

Caralluma fimbriata Extract Improves Vascular Dysfunction in Obese Mice Fed a High-Fat Diet

BACKGROUND

Obesity is a risk factor for developing cardiovascular diseases (CVDs) by impairing normal vascular function. Natural products are gaining momentum in the clinical setting due to their high efficacy and low toxicity. Caralluma fimbriata extract (CFE) has been shown to control appetite and promote weight loss; however, its effect on vascular function remains poorly understood. This study aimed to determine the effect that CFE had on weight loss and vascular function in mice fed a high-fat diet (HFD) to induce obesity, comparing this effect to that of lorcaserin (LOR) (an anti-obesity pharmaceutical) treatment.

METHODS

C57BL/6J male mice (n = 80) were fed a 16-week HFD to induce obesity prior to being treated with CFE and LOR as standalone treatments or in conjunction. Body composition data, such as weight gain and fat mass content were measured, isometric tension analyses were performed on isolated abdominal aortic rings to determine relaxation responses to acetylcholine, and immunohistochemistry studies were utilized to determine the expression profiles on endothelial nitric oxide synthase (eNOS) and cell stress markers (nitrotyrosine (NT) and 78 kDa glucose-regulated protein (GRP78)) in the endothelial, medial and adventitial layers of aortic rings.

RESULTS

The results demonstrated that CFE and CFE + LOR treatments significantly reduced weight gain (17%; 24%) and fat mass deposition (14%; 16%). A HFD markedly reduced acetylcholine-mediated relaxation (p < 0.05, p < 0.0001) and eNOS expression (p < 0.0001, p < 0.01) and significantly increased NT (p < 0.05, p < 0.0001) and GRP78 (p < 0.05, p < 0.01, p < 0.001). Obese mice treated with CFE exhibited significantly improved ACh-induced relaxation responses, increased eNOS (p < 0.05, p < 0.01) and reduced NT (p < 0.01) and GRP78 (p < 0.05, p < 0.01) expression.

CONCLUSIONS

Thus, CFE alone or in combination with LOR could serve as an alternative strategy for preventing obesity-related cardiovascular diseases.

Cellular, Molecular and Clinical Aspects of Aortic Aneurysm-Vascular Physiology and Pathophysiology

A disturbance of the structure of the aortic wall results in the formation of aortic aneurysm, which is characterized by a significant bulge on the vessel surface that may have consequences, such as distention and finally rupture. Abdominal aortic aneurysm (AAA) is a major pathological condition because it affects approximately 8% of elderly men and 1.5% of elderly women. The pathogenesis of AAA involves multiple interlocking mechanisms, including inflammation, immune cell activation, protein degradation and cellular malalignments. The expression of inflammatory factors, such as cytokines and chemokines, induce the infiltration of inflammatory cells into the wall of the aorta, including macrophages, natural killer cells (NK cells) and T and B lymphocytes. Protein degradation occurs with a high expression not only of matrix metalloproteinases (MMPs) but also of neutrophil gelatinase-associated lipocalin (NGAL), interferon gamma (IFN-γ) and chymases. The loss of extracellular matrix (ECM) due to cell apoptosis and phenotype switching reduces tissue density and may contribute to AAA. It is important to consider the key mechanisms of initiating and promoting AAA to achieve better preventative and therapeutic outcomes.

Existence of Quantum Pharmacology in Sartans: Evidence in Isolated Rabbit Iliac Arteries

Quantum pharmacology introduces theoretical models to describe the possibility of ultra-high dilutions to produce biological effects, which may help to explain the placebo effect observed in hypertensive clinical trials. To determine this within physiology and to evaluate novel ARBs, we tested the ability of known angiotensin II receptor blockers (ARBs) (candesartan and telmisartan) used to treat hypertension and other cardiovascular diseases, as well as novel ARBs (benzimidazole-N-biphenyl tetrazole (ACC519T), benzimidazole-bis-N,N'-biphenyl tetrazole (ACC519T(2)) and 4-butyl-N,N0-bis[[20-2Htetrazol-5-yl)biphenyl-4-yl]methyl)imidazolium bromide (BV6(K+)2), and nirmatrelvir (the active ingredient in Paxlovid) to modulate vascular contraction in iliac rings from healthy male New Zealand White rabbits in responses to various vasopressors (angiotensin A, angiotensin II and phenylephrine). Additionally, the hemodynamic effect of ACC519T and telmisartan on mean arterial pressure in conscious rabbits was determined, while the ex vivo ability of BV6(K+)2 to activate angiotensin-converting enzyme-2 (ACE2) was also investigated. We show that commercially available and novel ARBs can modulate contraction responses at ultra-high dilutions to different vasopressors. ACC519T produced a dose-dependent reduction in rabbit mean arterial pressure while BV6(K+)2 significantly increased ACE2 metabolism. The ability of ARBs to inhibit contraction responses even at ultra-low concentrations provides evidence of the existence of quantum pharmacology. Furthermore, the ability of ACC519T and BV6(K+)2 to modulate blood pressure and ACE2 activity, respectively, indicates their therapeutic potential against hypertension.