CHARACTERISTICS OF CARDIAC-HYPERTROPHY IN THE JUVENILE VISCERAL STEATOSIS MOUSE WITH SYSTEMIC CARNITINE DEFICIENCY

The juvenile visceral steatosis (JVS) mouse exhibits hereditary system ic carnitine deficiency and develops cardiac hypertrophy. The aim of t his study was to clarify the characteristics of cardiac hypertrophy in the JVS mouse. Total carnitine content in JVS mouse heart was about 1 0% of that of control mouse heart at 4 and 8 weeks of age. The heart w eight/body weight ratio was bigger in JVS mice than that in control mi ce at 2 weeks of age. and this difference in ratio increased with age. The wall areas of both ventricles and septum in JVS mice were larger than those of the control mice at 2 and 8 weeks. The myocyte diameter in both ventricular walls and septum in JVS mice was longer than that of the control mice. On electron microscopy, the percent of mitochondr ia in the myocyte was 66% in JVS mice, and 37% in control mice. The pe rcent of lipid fraction in JVS mice was six-fold higher than that in c ontrol mice. Total content of adenine nucleotides in JVS mouse heart w as about 60% of that in control mouse heart. Adenylate energy charge i n JVS mouse heart was 63 and 45% of that in the control mouse heart at 4 and 8 weeks, respectively. Overall, the cardiac enlargement observe d in this animal model could be accounted for by a proportional increa se in the myocyte diameter in the ventricles and septum, accompanied b y an increase in mitochondria. Furthermore, this cellular growth is as sociated with decreases in the levels of ATP and ADP, adenylate energy charge. (C) 1998 Academic Press Limited.