RESUMO
The ideal drug for treatment of wide range of supraventricular arrhythmia has yet to be developed. For cardiovascular disease, herbal treatments are suitable alternatives for synthetic drugs due to their availability, minimal side effects and lower price. Previous studies showed antihypertensive, negative inotropic activities of Urtica dioica [Nettle]. The aims of the present study were: 1] to determine concentration-dependent effects of ethanolic extract of nettle on the nodal basic and functional properties. 2] to campare mechanism of action nettel with ouabaine. Male Newsland rabbits [1-1.3 kg] were used in all of experiments; various experimental stimulating protocols [WBCL; Recovery, Facilitation, Fatigue] were applied to assessing electrophysiological properties of Node. We used isolated perfused AV-nodal preparation [n=24]. All protocols were repeated in the presence and absence [control] of different concentration [0.25 - 0.5-1 g/1] of Nettle and ouabaine [0.l microM]. Results were shown as Mean +/- SE and a probability of 5% was taken to indicate statistical significance. We had considerable depression in basic and functional properties of node after adding Nettle, as WBCL, Effective refractory period, Functional refractory period and nodal conduction Time significantly increased [p<0.05]. In addition magnitude of fatigue [deltaAH] and deltaFRP [Amount of facilitation] significantly increased [p<0.05]. The above results showed potential antiarrhythmic properties of [Urtica dioica] by increasing fatigue and nodal refractoriness. Therefore, it may be considered for treatment of supraventicular arrhythmias
RESUMO
Herbal treatments are suitable replacement for synthetic drugs due to their availability, minimal side effects and low price. Previous studies about pharmacologic and biochemical effects of Allium sativum [garlic] have shown antihypertensive, anti arrhythmic, negative inotropic and chronotropic activities. The aim of this study was to assess the effects of liquid extract of Allium sativum on the basic and rate-dependent electrophysiological properties of isolated atrioventricular [AV] nodal of rabbit. In the present study we used isolated perfused AV-Nodal rabbit [1.5-2 kg] preparation including right atrium, intra-atrial septum and His bundle of rabbit as an experimental model to determine the effects of various concentration of aqueous extract of Allium Sativum. Selective stimulation protocols [recovery, facilitation and fatigue] were used to independently assess AV nodal properties in 14 rabbits [two groups]. In the first group of experiment [n=8 rabbits], different concentrations [20, 30, 100, 850 mg/lit] of Allium Sativum and in the second group verapamil [0.1 m] [n=6 rabbits] was applied. Data were analyzed using ANOVA and Wilcaxon tests. The results of this research indicate a significant effect of various concentrations of Allium sativum on basic electrophysiological parameters of atrioventricular node [WBCL, recovery, facilitation, fatigue] and fatigue [P<0.05]. In the presence of garlic [20 mg/lit], AVCT [atrioventricular conduction time] increased from 41.3 +/- 5.3 to 45.6 +/- 5.1msec and FRP [functional refractory period] increased from 108.6 +/- 14.4 to 167 +/- 1.1 msec [P<0.05]. The Allium sativum extract has less inhibitory effect in comparison with verapamil on the basic parameters [P<0.05] of Node. The above results showed potential antiarrhythmic properties of Allium sativum by increasing fatigue and refractory period. Therefore, it may be considered for treatment of supraventricular arrhythmias