Surgical preparation
Femoral veins were cannulated for venous access for drug administration. The right common carotid and a femoral artery were accessed for measurement of left ventricular pressure and recording of blood pressure using a Druck PDCR 75 or a Bell and Howell type 4-422-0001 pressure transducer. A tracheotomy was performed to facilitate respiration, and a wide bore cannula secured in place. Subcutaneous stainless steel needle electrodes were inserted to each limb for the recording of the electrocardiogram (ECG). All animals were maintained at a rectal temperature of 37 °C.