F. Coulson

Resveratrol Prevents Cardiovascular Complications in the SHR/STZ Rat by Reductions in Oxidative Stress and Inflammation

The cardioprotective effects of resveratrol are well established in animal models of metabolic disease but are yet to be investigated in a combined model of hypertension and diabetes. This study investigated the ability of resveratrols antioxidant and anti-inflammatory effects to prevent cardiovascular complications in the spontaneously hypertensive streptozotocin-induced diabetic rat. Diabetes was induced in eight-week-old male spontaneously hypertensive rats via a single intravenous injection of streptozotocin. Following this, resveratrol was administered orally for an eight-week period until the animals were sixteen weeks of age. Upon completion of the treatment regime assessments of oxidative stress, lipid peroxidation, inflammation, and cardiovascular function were made. Resveratrol administration to hypertensive-diabetic animals did not impact upon blood glucose or haemodynamics but significantly reduced oxidative stress, lipid peroxidation, and inflammatory cytokines. Reductions in systemic levels of oxidative stress and inflammation conferred improvements in vascular reactivity and left ventricular pump function and electrophysiology. This study demonstrates that resveratrol administration to hypertensive diabetic animals can elicit cardioprotective properties via antioxidant and anti-inflammatory effects. The observed preservation of cardiovascular function was independent of changes in blood glucose concentration and haemodynamics, suggesting that oxidative stress and inflammation are key components within the pathological cascade associated with hypertension and diabetes.

Effects of resveratrol and nebivolol on isolated vascular and cardiac tissues from young rats.

The mechanisms by which resveratrol and nebivolol induce vasodilation are not clearly understood. It has been postulated that both agents stimulate the production of nitric oxide; however, this remains to be conclusively established. The major aim of this study was to examine the vasodilatory and antiarrhythmic effects of both resveratrol and nebivolol and to provide further insight into possible mechanisms of action. Cardiac and vascular tissues were isolated from healthy male rodents. Results indicate that resveratrol and nebivolol decrease the action potential duration and induce mild vasorelaxation in aortic and mesenteric segments. Relaxation induced by resveratrol was prevented by the addition of verapamil, Nω-nitro-L-arginine-methyl ester, and 4-aminopyridine. This suggests that nebivolol and resveratrol act as putative antiarrhythmic and vasodilatory agents in vitro through possible indirect nitric oxide mechanisms.

The WellingTONNE Challenge Toolkit: Using the RE-AIM Framework to Evaluate a Community Resource Promoting Healthy Lifestyle Behaviours.

Objective: The RE-AIM framework has been recognized as a tool to evaluate the adoption, delivery, and sustainability of an intervention, and estimate its potential public health impact. In this study four dimensions of the RE-AIM framework (adoption, implementation, effectiveness, and maintenance) were used to evaluate the WellingTONNE Challenge Toolkit, a step-by-step resource explaining how to develop, implement and disseminate a healthy lifestyle community intervention. Design: Process evaluation. Methods: In association with the Commonwealth Department of Health and Ageing (DHA), a self-report questionnaire was distributed to individuals from health care organizations, local councils and community organizations throughout Australia who had received and/or requested the WellingTONNE Challenge Toolkit from the DHA. Results: The RE-AIM dimensions revealed a high adoption rate and confirmed that the toolkit was being implemented for what it was intended to be implemented for and was an effective resource for initiating, maintaining and encouraging a healthy lifestyle. Lastly, the evaluation highlighted that most participants would maintain use of the toolkit in future projects. Conclusion: The RE-AIM framework provided valuable information concerning the uptake, implementation and usability of the WellingTONNE Challenge Toolkit, however, future research should address the behavioural outcomes associated with using the toolkit in order to provide a clearer understanding of how research can be translated into public health practice.

Electrophysiological, vasoactive, and gastromodulatory effects of stevia in healthy Wistar rats.

Antihypertensive and antidiabetic effects of stevia, Stevia rebaudiana (Asteraceae), have been demonstrated in several human and animal models. The current study aims to define stevias role in modifying the electrophysiological and mechanical properties of cardiomyocytes, blood vessels, and gastrointestinal smooth muscle. Tissues from thoracic aorta, mesenteric arteries, ileum, and left ventricular papillary muscles were excised from 8-week-old healthy Wistar rats. The effects of stevia (1 × 10-9 M to 1 × 10-4 M) were measured on these tissues. Stevias effects in the presence of verapamil, 4-AP, and L-NAME were also assessed. In cardiomyocytes, stevia attenuated the force of contraction, decreased the average peak amplitude, and shortened the repolarisation phase of action potential - repolarisation phase of action potential20 by 25 %, repolarisation phase of action potential50 by 34 %, and repolarisation phase of action potential90 by 36 %. Stevia caused relaxation of aortic tissues which was significantly potentiated in the presence of verapamil. In mesenteric arteries, incubation with L-NAME failed to block stevia-induced relaxation indicating the mechanism of action may not be fully via nitric oxide-dependent pathways. Stevia concentration-dependently reduced electrical field stimulated and carbachol-induced contractions in the isolated ileum. This study is the first to show the effectiveness of stevia in reducing cardiac action potential duration at 20 %, 50 %, and 90 % of repolarisation. Stevia also showed beneficial modulatory effects on cardiovascular and gastrointestinal tissues via calcium channel antagonism, activation of the M2 muscarinic receptor function, and enhanced nitric oxide release.