Effect of glucagon on amitriptyline-induced cardiovascular toxicity in rats

The aim of this study was to investigate the effect of glucagon on cardiovascular parameters in anesthetized rat model of tricyclic antidepressant overdose. Toxicity was induced by infusion of amitriptyline 0.94 mg/kg/min until a 40-45% of reduction in mean arterial pressure was observed. Amitriptyline infusion rats were then randomized into three groups. Control group of rats (group 1) received a bolus of 5% dextrose followed by the continuous infusion of dextrose, whereas treatment groups received 1 mg/kg (group 2) or 2 mg/kg (group 3) bolus doses of glucagon followed by continuous infusion (0.1 mg/kg/min) of glucagons for 60 min. Mean arterial pressure, heart rate, and electrocardiogram were recorded. Amitriptyline caused a significant decrease in mean arterial pressure and a prolongation in QRS, yet it did not change the heart rate. High-bolus dose of glucagon (2 mg/kg) followed by glucagon infusion significantly increased mean arterial pressure at 40, 50, and 60 min (P < 0.05) and shortened the prolonged QRS at 50 and 60 min (P < 0.05) when compared with control group. There was also a significant increase in heart rate. In conclusion, bolus doses followed by a continuous infusion of glucagon were found to be effective in reversing the hypotension and QRS prolongation in the rat model of amitriptyline toxicity. Further studies are needed to reveal the exact mechanism of the proposed effect

The role of adenosine receptors on amitriptyline-induced electrophysiological changes on rat atrium

We investigated the role of adenosine receptors in amitriptyline-induced cardiac action potential (AP) changes in isolated rat atria. In the first group, APs were recorded after cumulative addition of amitriptyline (1 mu M, 10 mu M and 50 mu M). In other groups, each atrium was incubated with selective adenosine A(1) antagonist (8-cyclopentyl-1,3-dipropylxanthine (DPCPX), 10(-4) M) or selective adenosine A(2a) receptor antagonist (8-(3-chlorostyryl) caffeine, 10(-5) M) before amitriptyline administration. Resting membrane potential, AP amplitude (APA), AP duration at 50% and 80% of repolarization (APD(50) and APD(80), respectively), and the maximum rise and decay slopes of AP were recorded. Amitriptyline (50 mu M) prolonged the APD(50) and APD(80) (p < 0.001) and the maximum rise slope of AP was reduced by amitriptyline (p < 0.0001). Amitriptyline reduced maximum decay slope of AP only at 50 mu M (p < 0.01). DPCPX significantly decreased the 50-mu M amitriptyline-induced APD(50) and APD(80) prolongation (p < 0.001). DPCPX significantly prevented the effects of amitriptyline (1 mu M and 50 mu M) on maximum rise slope of AP (p < 0.05). DPCPX significantly prevented the amitriptyline-induced (50 mu M) reduction in maximum decay slope of AP (p < 0.001). The selective adenosine A(1) receptor antagonist prevented the electrophysiological effects of amitriptyline on atrial AP. A(1) receptor stimulation may be responsible for the cardiovascular toxic effects produced by amitriptyline

Weighing Diverse Theoretical Models on Turkish Maqam

Since the early 20th century, various theories have been advanced in order to mathematically explain and notate modes of Traditional Turkish music known as maqams. In this article, maqam scales according to various theoretical models based on different tunings are compared with pitch measurements obtained from select recordings of master Turkish performers in order to study their level of match with analysed data. Chosen recordings are subjected to a fully computerized sequence of signal processing algorithms for the automatic determination of the set of relative pitches for each maqam scale: f0 estimation, histogram computation, tonic detection + histogram alignment, and peak picking. For nine well-recognized maqams, automatically derived relative pitches are compared with scale tones defined by theoretical models using quantitative distance measures. We analyse and interpret histogram peaks based on these measures to find the theoretical models most conforming with all the recordings, and hence, with the quotidian performance trends influenced by them.TÜBİTA