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.