Concentration of myocardial cyclic AMP and ventricular fibrillation induced by aminophylline.

The concentration of myocardial cyclic AMP was measured in 9 dogs by radioimmunoassay after the administration of aminophylline. Fourteen dogs served as control. The concentration of cyclic AMP in the left ventricle was the highest and the lowest value was obtained in the right atrium in the control dogs.

Dopamine-beta-hydroxylase activity after acute myocardial infarction.

Serum dopamine-beta-hydroxylase (DBH) activities of 74 apparently healthy adults were not distributed normally, but skewed to the right. There were at least 2 subgroups in the distribution of DBH activity. Accordingly, 27 serial serum DBH activities following acute myocardial infarction were divided into 2 subgroups according to their activities on the 10th day or/and thereafter.

Serum dopamine beta-hydroxylase in cardiovascular diseases.

Dopamine-beta-hydroxylase (DBH), the enzyme responsible for the biosynthesis of norepinephrine from dopamine was assayed in the blood serum of 23 normal adults, 16 patients with congestive heart failure, 19 patients with asymptomatic ischemic heart disease, 4 patients with angina pectoris at rest, 15 patients with essential hypertension, 8 patients with essential hypotension, 5 patients with neurocirculatory asthenia, and 9 normal adults before and after the exercise test. The serum DBH activity varied within a wide range in the control population. The DBH activity increased about 16% after the exercise stress.

Dopamine-beta-hydroxylase activity after acute myocardial infarction.

After acute myocardial infarction, serial serum dopamine-beta-hydroxylase (DBH) activity was elevated in both high and low DBH subgroups. The observed increase in DBH activity on the first, second, and third days after acute myocardial infarction suggests an augmentation in sympathetic nervous system activity after acute myocardial infarction.

Arrhythmogenic effects of acute free fatty acid mobilization on ischemic heart.

The mechanism of action of the acute abnormal rise of plasma free fatty acids (FFA) in the provocation of arrhythmia in ischemic heart was studied by means of electron spin resonance (ESR) spectrometer. A sudden and abnormal rise of plasma FFA caused a significant fall of the respiratory control index (RCI) of the amount of free radical myocardial mitochondria in state 4 respiration. Based on these findings, a sudden and abnormal rise of plasma FFA seems to further facilitate the uncoupling of oxidative phosphorylation in the myocardial mitochondria of the ischemic portion of the heart.

Studies on myocardial mitochondria in failing dog hearts: studies by electron spin resonance (ESR) spectrometry.

The formation of free radicals, which was represented by the concentration of free radicals in state 4 respiration, and the respiratory control ratio were studied in the myocardial mitochondria isolated from dog hearts that were failing due to aortic constriction. Both formation and respiratory control ratio were lowered, compared to each control value, in acute and chronic heart failure. A positive correlation was recognized between free radicals in state 4 respiration and respiratory control ratio.