1.P.143 Terminalia arjuna — the cardiovascular friendly plant

Terminalia arjuna improves cardiovascular autonomic neuropathy in streptozotocin-induced diabetic rats

The present study was designed to examine the therapeutic potential of Terminalia arjuna bark extract in improving cardiovascular autonomic neuropathy in Streptozotocin (STZ)-induced diabetic Wistar Albino rats. The baroreflex was evaluated by measuring the changes in heart rate with changes in arterial blood pressure induced by bolus injections of phenylephrine (vasoconstrictor) and sodium nitroprusside (vasodilator). T. arjuna bark extract, Rosuvastatin and Insulin were tested/administered therapeutically in rat model of uncontrolled diabetes. After 8 weeks of STZ administration, the reflex bradycardia and tachycardia response to hypertension and hypotension, respectively, were impaired in the diabetic group. The reflex bradycardia improved significantly after 1 month treatment of T. arjuna while the reflex tachycardia could not improve. The decreased body weight, heart rate, blood pressure and raised blood sugar in diabetic rats were not improved by T. arjuna therapy. Rosuvastatin treatment exerted similar effects while Insulin improved all the parameters. Further T. arjuna, Rosuvastatin and Insulin significantly reduced oxidative stress and inflammatory cytokine levels in diabetic rats. Results suggest that T. arjuna bark extract improves the altered baroreflex sensitivity in diabetic rats possibly through maintaining endogenous antioxidant enzyme activities and decreasing cytokine levels.

Improvement in myocardial function by Terminalia arjuna in streptozotocin-induced diabetic rats: possible mechanisms

Vascular complications are a leading cause of mortality and morbidity in diabetic patients. Herbal drugs are increasingly being used in the treatment of cardiovascular disorders. The present study was designed to examine the therapeutic potential of Terminalia arjuna bark extract in improving myocardial function in streptozotocin (STZ)-induced diabetic rats. After 8 weeks of STZ administration, rats showed a decline in left ventricular pressure (LVP), maximal rate of rise and fall in LVP (LV [dP/dt] max and LV [dP/dt] min), cardiac contractility index (LV [dP/dt] max/LVP), and rise in LV end-diastolic pressure. Altered lipid profile, oxidative stress, and increased levels of endothelin 1 (ET-1), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) along with histological changes in heart and pancreas were observed in diabetic rats. T arjuna significantly attenuated cardiac dysfunction and myocardial injury in diabetic rats. It also reduced oxidative stress, ET-1, and inflammatory cytokine levels. The decreased body weight, heart rate blood pressure, and raised blood sugar in diabetic rats did not improve after T arjuna therapy. Results suggest that T arjuna bark extract improves the altered myocardial function in diabetic rats possibly through maintaining endogenous antioxidant enzyme activities, decreasing ET-1 and cytokine levels.

Possible mechanisms of hypotension produced 70% alcoholic extract of Terminalia arjuna (L.) in anaesthetized dogs

Background

The bark of Terminalia arjuna L. (Combretaceae) is used in Ayurveda since ancient times for the treatment of cardiac disorders. Previous laboratory investigations have demonstrated the use of the bark in cardiovascular complications. The present study was aimed to find the effect of 70% alcoholic extract of Terminalia arjuna on anaesthetized dog blood pressure and probable site of action.

Methods

Six dogs were anaesthetized with intraperitoneal injection of thiopental sodium and the blood pressure of each dog (n = 6) was measured from the left common carotid artery connected to a mercury manometer on kymograph. The femoral vein was cannulated for administration of drug solutions. The extract of T. arjuna (dissolved in propylene glycol) in the dose range of 5 to 15 mg/kg were administered intravenously in a pilot study and the dose (6 mg/kg) which produced appreciable hypotension was selected for further studies.

Results

Intravenous administration of T. arjuna produced dose-dependent hypotension in anaesthetized dogs. The hypotension produced by 6 mg/kg dose of the extract was blocked by propranolol but not by atropine or mepyramine maleate. This indicates that muscarinic or histaminergic mechanisms are not likely to be involved in the hypotension produced by the extract. The blockade by propranolol of the hypotension produced by T. arjuna indicates that the extract might contain active compound(s) possessing adrenergic ß₂-receptor agonist action and/or that act directly on the heart muscle.

Conclusion

The results indicated the likely involvement of peripheral mechanism for hypotension produced by the 70% alcoholic extract of Terminalia arjuna and lends support for the claims of its traditional usage in cardiovascular disorders.