The cardiodynamic and metabolic effects of @entity72919 and XXXX on the isolated @entity235 heart.

@entity1169 @entity72919 @entity712 @entity235 @entity26
In the isolated @entity235 heart-lung preparation modified to measure coronary outflow and myocardial @entity26 consumption, an infusion of @entity72919 of 1 mg/min produced an increase in coronary outflow of 120.0% and a decrease in myocardial @entity26 consumption of 11.0% at a cumulative dose of 28.0 +/- 3.8 mg, resulting in an increase in efficiency of 22.4%. At a total dose of 40 mg, the corresponding figures were +181.0%, -15.0% and +38.0% respectively. No change in heart rate was observed. An infusion of @entity1169 of 1 mg/min, on the other hand, was characterized by decreases in myocardial contractility and heart rate starting with cumulative doses of 20 mg and 40 mg respectively. At a cumulative dose of 62.9 +/- 3.0 mg a marked degree of @entity712 occurred (peak failure) characterized by a decrease in cardiac output (-53.3%), dp/dt (-50.8%), heart rate (-18.5%) and myocardial @entity26 consumption (-25.5%). In a separate series exposed to the same infusion of @entity1169 but in which the decrease in heart rate was prevented by pacing, identical changes were observed except that myocardial @entity26 consumption decreased only by 7.7%. It may be concluded from this study that @entity72919 , in confirmation of reports by other investigators, increases coronary outflow markedly. @entity72919 decreases myocardial @entity26 consumption by a direct effect on myocardial metabolism as is evident from the fact that this decrease is not accompanied by changes in any of the parameters which are known to influence myocardial @entity26 consumption such as heart rate. @entity1169 has no effect on myocardial @entity26 consumption unless it is given in a dose which produces @entity712 and a decrease in heart rate. The decrease in heart rate following @entity1169 bears a close relationship to the decrease in myocardial @entity26 consumption.
