Pretreatment with catecholamines can suppress severe ventricular arrhythmias in rats: ANIMALS AND METHODS (part 1)
Isolated heart preparation
Perfusion technique: All studies were performed in accordance with the Guide for the Care and Use of Laboratory Animals, published by the United States National Institutes of Health (NIH publication No 85-23, revised 1985). Hearts were excised from heparinized (500 U intraperitoneally) and anesthetized (sodium pentobarbitone 40 mg/kg intraperi-toneally) male Wistar rats (250 to 300 g) and perfused (Langendorff mode) at a constant flow rate of 10 mL/min. Krebs-Henseleit solution contained (in mM) NaCl 118.0, KCl 3.2, MgSO4 1.2, NaHCO3 25.0, NaH2PO4 1.18, CaCl2 2.5, glucose 11.1, and sodium pyruvate 2.0, saturated with 95% oxygen and 5% carbon dioxide, and maintained at 37°C at pH 7.4. Epicardial electrocardiogram (ECG) was recorded by means of two stainless steel electrodes attached to the apex of the heart and the aortic cannula. Heart rate was calculated from the ECG and continuously monitored on mingograph (Elema-Siemens, Solna, Sweden).
Perfusion protocol: After 20 mins equilibration, hearts (n=15) were subjected to regional ischemia induced by occlusion of the left anterior descending (LAD) coronary artery and maintained for 30 mins. Efficacy of occlusion was confirmed by a 45% increase in perfusion pressure. In the noradrenaline-treated group (n=18), exogenous noradrenaline (Arterenol, Sigma Chemical Co, St Louis, Missouri, USA) was introduced before the onset of ischemia in a manner mimicking IP, ie, 5 min infusion (10-6M) followed by 10 min washout. After 30 mins of ischemia the hearts were freeze-clamped and stored at -70°C for estimation of Na+/K+-ATPase activity. The same procedure was performed in the time-matched treated and untreated controls (n=9 for each group). You will always find the required amount of discount Cialis Professional at the pharmacy that will be happy to take best care of you by offering safe possibility to purchase the drugs you need without any need to get a prescription first or take any other extra steps.