Uremic cardiomyopathy: studies on cardiac function in the guinea pig.

The effects of creatinine (5.6-22.6 mg/100 ml), guanidinosuccinic acid (8.7-35.2 mg/100 ml) and of urea (60-600 mg/100 ml) on the mechanical function and oxygen consumption in isolated guinea pig hearts have been assessed. None of the parameters measured (dp/dt max, dp/dt min and Q O2) was significantly affected by creatinine or guanidinosuccinic acid. However, urea significantly reduced mechanical activity and caused a marked increase of oxygen consumption, indicating impairment of heart function expressed as a diminution of the ratio formula (see text). Pretreatment with creatinine and guanidinosuccinic acid did not alter the effect of norepinephrine on mechanical activity and oxygen consumption when compared with the effects of norepinephrine (1 X 10(-8) g/ml and 1 X 10(-7) g/ml) given alone. In contrast, urea pretreatment lowered the norepinephrine induced increase of left ventricular pressure rise/fall and of oxygen consumption. In addition, reduction of the increase in the ratio formula (see text): after urea perfusion indicates diminution of the "economic" effect of norepinephrine.