Conditioning guinea-pig hearts in vitro for torsade de pointes arrhythmias (part 3)

pointes arrhythmias (part 3)

The stabilization period lasted at least 30 mins before any drug infusion. Endocardial ECG was derived from the right ventricle by means of a small bipolar catheter introduced via the pulmonary artery. Force of contraction was measured within the left ventricle by means of a water-filled rubber balloon preloaded to 15 mmHg and connected to a pressure transducer (Isotec, Hugo Sachs Electronik).Recordings were made on a polygraph (Schwarzer, Munich, Germany). QTc was calculated according to Bazett’s formula , which is validated for the guinea-pig ECG . The experimental design with the perfusion protocols and number of hearts are detailed in the figure captions.
Drugs in stock solutions of 10-5 |J.M were added to the coronary inflow close to the aortic valves by means of a per-fusor (Braun, Melsungen, Germany) at an infusion rate of 0.75 mL/min adapted to the coronary flow rate of 15 mL/min to obtain required final concentrations within the perfusate. Final concentrations of 0.5 |iM DPI 201-106 plus 0.5 |iM veratridine were chosen based on previous experience with these drugs in the guinea-pig myocardium . Drugs used were DPI 201-106 (4-[3-(4-diphenyl-methyl-1-piper-azinyl)-2-hydroxypropoxy]-1H-indole-2-carbonitrile, San-doz, Basel, Switzerland) and veratridine (Sigma, St Louis, Missouri, USA). It’s time to pay less money – just get relieve allergy symptoms at the best online pharmacy.

The statistical significance of differences between mean values was assessed by the t test.

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