p. KEZDI, S. N. MISRA, R. K. KORDENAT AND T. J. SMITH 
63 
through the right common carotid artery which 
is exposed together with the external jugular 
vein. The catheter, placed through the jugular 
vein, is advanced to the right atrium, the pul- 
monary artery, or the coronary sinus depending 
upon the experimental protocol. A second ar- 
terial catheter is placed through the femoral ar- 
tery and advanced into the left ventricle. The 
surgical exposures are then sutured and the 
wounds bandaged. At the end of the procedure 
the animal is usually awake. The animals are 
then given morphine sulfate, 15 mg IM, approx- 
imately in hourly intervals to maintain slight 
sedation. They are placed on their side on a 
blanket and covered to maintain body warmth. 
Water is given to them ad libitum. 
The left ventricular and arterial catheters, 
the pulmonary artery catheters are connected to 
pressure gauges and pressures are continuously 
monitored. A single lead electrocardiogram is 
also monitored. Cardiac outputs are performed 
in duplicate by the dye dilution technique using 
2.5 mg indocyanine green as a bolus in the pul- 
monary artery. Arterial blood is withdrawn 
through a Gilford densitometer using a Har- 
vard constant withdrawal infusion pump. Ar- 
terial, venous, and coronary sinus blood samples 
can be withdrawn and Oo, CO2 tension, pH, 
lactates, pyruvates, electrolytes, and serum en- 
zymes be determined. In a number of experi- 
ments, we have determined myocardial oxygen 
consumption and lactate production and calcu- 
lated excess lactate according to the formula of 
Huckabee. Blood volumes were also measured 
by the radioactive tagged albumin tech- 
nique. In another series of experiments, left 
ventricular end diastolic and end systolic vol- 
umes and cardiac output were obtained in dupli- 
cate by the method of Shaffer.*' Ejection 
fraction was calculated from this data. 
Following the baseline studies to determine 
the hemodynamic and biochemical variables, .2 
ml metallic mercury is injected into the catheter 
previously placed in the circumflex artery and 
