182 
CARDIAC MODELS 
Figure 3. — Representation of the surgical procedure for producing acute coronary occlusion in the unanesthetized 
dog. 
at any of the time periods. Kininase (KNASE) 
activity was increased greatly at all time 
periods in the control dogs, while this activity 
remained at near-normal levels in the drug- 
treated dogs. SGOT values were increased in 
both groups of dogs at the 24-hour time period. 
SUMMARY 
These studies are but preliminary and, as 
such, do not permit interpretation at this time. 
An experimental model has been described that 
allows for the sequential analysis of components 
of three protease systems prior to and during 
an acute myocardial ischemic episode. It would 
appear that more frequent blood sampling 
would be valuable in determining the direction 
of change during the initial acute phase of the 
occlusion. In addition, biochemical changes as 
determined from venous samples may or may 
not reflect critical changes occurring at the 
local myocardial site. Blood samples drawn 
directly from the coronary vessels at the time 
of occulsion might allow for more accurate 
evaluation of those immediate changes occur- 
ring at the local site. 
Additional studies are planned to determine 
the significance of some of the biochemical 
changes, to be correlated with histopathology 
data. The effect of protease inhibitor treatment 
also will be assessed, both in an attempt to 
clarify the role of proteases in this condition, 
and as a therapeutic possibility. While throm- 
bolytic agents are considered to form one of the 
bases for rational therapy throughout most 
stages following coronary occlusion inhibi- 
tor therapy may be worthy of consideration in 
the very early post-occlusive phase, where pro- 
tease activation may be dominant but unde- 
tected hithertofore. 
