Preclinical abnormality of cardiac function in juvenile-onset type diabetics: The effects of autonomic nervous blocking and dynamic exercise on cardiac function

Abstract

The cardiac function and the autonomic nervous function of the juvenile-onset type diabetics (ranging from 15 to 29 years) who had no obvious cardiovascular complication on clinical diagnosis were studied by autonomic nervous blocking and dynamic exercise. The following results were obtained. There was a greater increase of heart rate in the diabetics at rest and after the injection of propranolol, but exercise without autonomic nervous blocking showed no difference in cardiovascular responses between the diabetics and the normal subjects. After the injection of both propranolol and atropine, the diabetics had a significant reduction of PWE, mPWV and ETi in comparison with the normal subjects. During the exercise after the injection EF, mVCF and PWE increased in the normals, but those parameters were unchanged in the diabetics. The results show that: the vagal tone is more decreased in diabetics than in normals, and that this dysfunction may lead to the tachycardia as a manifestation of diabetic autonomic neuropathy; and that the impairment of diabetics cardiac performance can be a possible pathogenesis of diabetic cardiomyopathy