Cardioprotective effects of exogenous and endogenous hydrocortisone in the rabbit model of ischemia-reperfusion Efectos cardioprotectores de la hidrocortisona exógena y endógena en el modelo isquemia-reperfusión de conejo

Reducing the infarct size in acute myocardial infarction is one of the most important goals driving new drug research and development. During the last two decades, many clinical studies have found cardioprotective effects of corticosteroids, but their exact role in ischemic preconditioning remains questionable. The aim of the present study was to determine the protective effects of hydrocortisone sodium succinate on myocardial preconditioning in rabbit hearts. Twenty-four male New Zealand rabbits were divided randomly & equally in four groups: 1) control, 2) Infarct, 3) Ischemic preconditioning (IP) and 4) Hydrocortisone (HYD). The HYD group received 50mg/kg Hydrocortisone 45min before major ischemia. Serum levels of cardiac troponin-T(cTNT) and cortisole were measured before and after the protocols. Triphenyl-tetrazolium chloride staining was used to determine the infarcted area. In the present study, exogenous hydrocortisone decreased infarct size by 53 in comparison to the infarct group. Serum level of cortisole was increased in the IP and HYD groups, and was significant in the HYD group (p0.01). In conclusion, we showed that hydrocortisone has cardioprotective effects when injected before the onset of myocardial infarction. In addition, we have proposed for the first time that endogenous hydrocortisone may play a role in ischemic preconditioning phenomena

Role of slow pathway after nodal fast pathway ablation on the basic and rate-dependent properties of the isolated rabbit atrioventricular node

Introduction: The aim of this study was to obtain new insights into the possible relations between functional properties of slow concealed pathway and rate-dependent properties of the AV-node. Methods: Rate-dependent nodal properties of recovery, facilitation, and fatigue were characterized by stimulation protocols in one group of isolated superfused AV-Nodal rabbits (n=7). Small miniature lesions were made by delivering constant voltage (110 V-100 s) with unipolar silver electrode. Results: Fast pathway ablation significantly decreased facilitation and had no effect on fatigue and nodal refractoriness. The most important effect of fast pathway ablation was prolongation of the minimum conduction time. Conclusion: The FP-ablation revealed the presence of the concealed SP. Rate-dependent property of the node is dependent to dynamic interaction between concealed slow with slow pathway. The fast pathway was involved in the mechanism of facilitation

A study of the role of nitric oxide in the mechanism of action of hydroalcoholic extract of saffron (Crocus sativus) on the electrophysiological properties of the rabbit atrioventricular node

Biologically active substances of plant origin represent an essential branch of modern cardiovascular pharmacotherapy. Furthermore, drugs of plant origin have the advantage of weaker adverse effects and lower prices than synthetic drugs. Pharmacological studies and traditional medical literature point to the anti-ischemic and hypotensive effects of the Crocus sativus L. (Iridacea). The major goals of the present study were: (1) to determine the negative dormotrophic properties of a hydroalcoholic extract of saffron on an isolated AV node and (2) to establish the role of nitric oxide in the mediating effects of saffron on the electrophysiological properties of the AV node. This was an experimental study. Selective stimulation protocols were used to independently quantify AV nodal recovery, facilitation and fatigue. We used isolated perfused rabbit AV node preparation, in three groups (N=32); in each group, we assessed the plant's effect in comparison with the control. In the pilot study, we used different concentrations (A=9 x 10-2 mg/L, B=19 x 10-2 mg/L and C=27 x 10-2 mg/L) to select the optimum concentration (19 x 10-2 mg/L) of the hydroalcoholic extract of saffron. Saffron has a depressant effect on basic and rate-dependent properties of the AV node. We observed an increasing AVCT (38.8 ±4 to 41.7 ±4 msec) and FRP (157.6 ±3 to 163.7 ±4 msec). Also saffron increased the amount of facilitation and the magnitude of fatigue (5.9 ±0.3 to 11.1 ±1 msec). The NOS inhibitor (L-NAME) has a preventative effect on the depressant effect of saffron on AVCT and FRP

The protective activity of Urtica dioica leaves on blood glucose concentration and β-cells in streptozotocin-diabetic rats

This study was done to determine the protective activity of the hydroalcholic extract of Urtica dioica leaves on Hyperglycemia and P-cells in hyperglycemic rats. Thirty Wistar rats were allocated in groups of normal, Diabetic and treatment. Hyperglycemia in Rats induced by 80 mg kg-1 streptozotocin. In treatment group, animals received hydroalcholic extract of Urtica dioica 100 mg kg-1 day-1 for five days, intraperitoneally and then hyperglycemia induced by streptozotocin. The blood glucose concentration was measured by using a Glucometer in 1st, 3rd and 5th weeks. In the end of 5th weeks the animals in each group were sacrificed by anesthesia and whole pancreas in three groups extracted and fixed in bouin's fluid and stained by chromealum hematoxiline-phloxine and beta cells were counted in three groups by Olympus microscope. Mean±SE of blood glucose concentrations in the end of fifth weeks were 99.4±5.0,454.7±34.5 and 303.6±100.6 in control, diabetic and treatment groups, respectively (p<0.05). The percentages of β-cells in control, diabetic and treatment groups were 73.6, 1.9 and 22.9%, respectively. The percentage of P-cells in treatment group comparing with diabetic group was significant (p<0.05). This study showed that the protective administration of hydroalcholic extract of Urtica dioica has hypoglycemic effect and protective activity of P-cells of langerhans in hyperglycemic rats. © 2007 Asian Network for Scientific Information

Lipid peroxidation in the serum of hypothyroid patients (In Gorgan-South East of Caspian Sea)

This study was designed to determine if lipid peroxidation can be modified by hypothyroidism. Twenty eight subjects with hypothyroidism and 33 euthyroid subjects participated in this study (2007). Blood samples were collected and serum malondialdehyde, T3, T4 and TSH were measured. An increase in lipid peroxidation (expressed as Malondialdehyde, MDA) and TSH levels and also a decrease in T4 level were observed in the hypothyroid patients when compared with control groups (p<0.001). The level of T3 was not changed when compared with control groups. The results shows that hypothyroidism may not modulate the free-radical-induced oxidative damage and that hypothyroidism may not present some protection against lipid peroxidation. Thus, the enhancedlipid peroxidation may play a role in the free-radical-induced oxidative damage of some tissues in hypothyroidism. These may show that there is an important relation between hypothyroidism and lipid peroxidation. © 2008 Academic Journals Inc

Myocardial infarct-sparing effect of ischemic preconditioning abrogated in cirrhotic rat through involvement of mitochondrial permeability transition pore

Despite all studies undertaken mechanism of cirrhotic cardiomyopathy the role of cirrhosis on ischemia-reperfusion (I/R) injury and ischemic preconditioning (IPC) phenomenon hasn't been explored yet. The aim of present study is to assess the relation between cirrhosis and IPC and the mitochondrial permeability transition pore (mPTP) role in IPC cardioprotective effects in cirrhotic rats. Material and method: Rat's heart were isolated and perfused with Krebs buffer by Langendorff method. Animals were equally divided into six groups (n=6): (I) I/R; hearts were subjected to 30 min ischemia and 45 min reperfusion, (II) IPC; IPC was induced via four cycle of 5 min regional ischemia followed by 5 min of reperfusion (III) common bile duct ligated (CBDL); hearts were subjected ischemia and reperfusion in cirrhotic rats, (IV) IPC-CBDL; four cycle of 5 min regional ischemia followed by 5 min of reperfusion in cirrhotic rats (V) CSA; Cyclosporine A was added 40 min prior to main ischemia (VI) CBDL+CSA. Results: Infarct size was increased significantly in IPC-CBDL group in comparison with IPC group (p< 0.05). Addition of CSA in CBDL+CSA group significantly decreased infarct size in comparison with IPC-CBDL group (p< 0.05). Ventricular arrhythmia severity was decreased significantly in IPC group compared to IR group, whereas it was increased significantly in IPC-CBDL group compared to IPC group (p< 0.05). CSA did not decrease arrhythmia score in CBDL group. Conclusion: The results showed that the cardioprotective effects of IPC are eliminated in cirrhosis. MPTP signaling in partly involve in cirrhotic cardiomyopathy

Prolongation of AV nodal refractoriness by Ruta graveolens in isolated rat hearts

Objectives: To evaluate concentration-dependent effects of total extract of Rusta graveolens and its purified alkaloid fraction on the nodal basic and functional properties. Methods: In the present experimental study, we used the Langendorff model for perfusion of isolated rat hearts to determine the effects of various concentrations of methanolic extract of Rue (1.25 × 10-6 weight per volume percent W/V; 2.5 × 10-6% W/V; 3.7 × 10-6 % W/ V) and total alkaloid of Rue (0.25 × 10-6% W/V; 0.5 × 10-6% W/V) on electrophysiological properties of cardiac tissue. Selective stimulation protocols were used to independently quantify atrioventricular (AV) nodal recovery, facilitation, and fatigue. We used 3 groups (N=24) of isolated perfused rat AV nodal preparations to assess the effect of Rue extracts. The study was carried out in October 2006 in the electrophysiology laboratory of the Cardiovascular Research Center of Golestan University of Medical Sciences, Golestan, Gorgan, Iran. Results: Our results showed that both the total plant extract and the alkaloid fraction of Ruta graveolens had a similar trend of action on nodal conduction time and refractorines. Furthermore, we observed increased atrioventricular conduction time (83±4 to 108±5 msec) and functional refractory period (157.6±3 to 163.7±4 msec) at a maximum concentration of 3.75 × 10-6% W/V. Conclusion: The above results indicated a potential antiarrhythmic effect of Ruta graveolens in treating supra ventricular tachyarrhythmia

Effect of Achillea santolina on mice spermatogenesis

Achillea santolina, a common variety of Achillea in Golestan province of Iran has been used in traditional medicine for its anti - inflammatory properties. The effect of hydroalcoholic extract (300 mg/kg/day Intraperitoneally, for 20 days) of Achillea santolina on the spermatogenesis of mice was studied by the evaluation of morphologic characteristics by light microscope. The alterations observed were disorganized germ epithelium, exfoliation of immature germ cells, germ cell necrosis and increased number of metaphasfis in germinal epithelium of seminiferous tubules. We concluded that hydroalcoholic extract of Achillea santolina 300 mg/kg/day intraperitoneally for 20 days as a different variety of Achillea has antispermatogenic effect similar to Achillea millefolium on mice

Protective effect of Urtica dioica L. (Urticaceae) on morphometric and morphologic alterations of seminiferous tubules in STZ diabetic rats

Objective(s): Urtica dioica L. has been known as a medicinal plant in the world. This study was conducted to determine the effects of the hydroalcoholic extract of Urtica dioica leaves on seminiferous tubules of diabetic rats. Materials and Methods: Animals were allocated to control, diabetic and protective groups. Treated animals received extract of U. dioica (100 mg/ kg/ day) IP for the first 5 days and STZ injection on the 6th day. After 5 weeks, testes removed and stained with H&E technique. Results: Tubular cell disintegration, sertoli and spermatogonia cell vacuolization, and decrease in sperm concentration observed in diabetic in comparison with control and protective groups. External seminiferous tubular diameter and seminiferous epithelial height significantly reduced (P< 0.05) in diabetic compared with controls, and these parameters increased (P< 0.05) in the treated compared with diabetics. Conclusion: Hydroalcoholic extract of U. dioica, before induction of diabetes; has protective role on seminiferous tubules alterations

The effect of aqueous extract of Crocus sativus on the electrophysiological properties of isolated perfused rabbit AV-node

In the present study we used isolated perfused AV-node of rabbit as an experimental model to determine the effect of various concentrations of extract of C. sativus (A = 9×10⁻², B = 19×10⁻², C = 28×10⁻², D = 37×10⁻² mg L⁻¹) on electrophysiological properties of isolated heart. Selective stimulation protocols were used to independently quantify AV nodal recovery, facilitation and fatigue in 12 rabbits. Our results showed concentration dependent depressant effects of aqueous extract of C. sativus on Wenchebach Cycle Length (WBCL), AV Conduction Time (AVCT), Functional Refractory Periods (FRP). C. sativus (28×10-2 mg L-1) prolonged AVCT from 44.4±5 (control) to 52.2±4 m sec, Rate-dependent properties such as Facilitation and fatigue significantly increased by 19×10⁻² mg L ⁻¹ of C. sativus. In control group magnitude of fatigue was 6.7±0.6 and increased by Saffron to 20±11.5 (p< 0.05). The effect of extract was prominent on fast pathway. The above results indicated differential effects of C. sativus on slow and fast pathways which has a dominant role on the fast pathway. This research for the first time has explained the role of saffron on the protective mechanism of artrioventricular node against supraventricular arrhythmia. These results showed the non-specific effect of saffron on the transitional cells of fast nodal pathway which was manifested as a rate-independent increase of basic and functional (facilitation and fatigue) parameters of artrioventricular node. © 2006 Asian Network for Scientific Information