EFFECT OF TEMPERATURE ON MYOCARDIAL-INFARCTION IN SWINE

Body core temperature in the normothermic range alters infarct size in rabbits. Moreover, temperature may modulate the protection by adenosi ne during a coronary artery occlusion. We investigated the effect of c ore temperature within the normothermic range (35-39 degrees C) on myo cardial infarct size produced by a 45-min coronary occlusion in open-c hest swine (n = 10), and we determined whether adenosine blockade with 8-phenyltheophylline and adenosine deaminase increased infarct size i n the normothermic range (n = 9). After 4 h of reperfusion the area at risk and infarct size were determined with Evans blue dye and triphen yltetrazolium chloride. Infarct size strongly correlated with temperat ure (r(2) = 0.71, P = 0.0001) so that at 35 degrees C no infarction oc curred and with each 1 degrees C increase in temperature 20% of the ar ea at risk became infarcted. In contrast, neither the low levels of co llateral flow (0.03 +/- 0.01 ml . min(-1) . g(-1)) nor the rate-pressu re product correlated with infarct size. In the normothermic range, ad enosine blockade had no effect on infarct size. The data demonstrate t hat temperature can exert a profound effect on infarct size but fail t o demonstrate a protective effect of endogenous adenosine at normother mic temperatures. Our findings emphasize the need for stringent contro l of core temperature during investigation of interventions aimed at r educing infarct size.