IMPAIRED EXPRESSION OF ATRIAL-NATRIURETIC-PEPTIDE IN DIABETIC RATS WITH MYOCARDIAL-INFARCTION

We evaluated the effects of myocardial infarction (MT) on the hemodyna mics and the expression of atrial natriuretic peptide (ANP) mRNA in ra ts with streptozotocin-induced diabetes. Eight weeks after streptozoto cin injection, the diabetic rats and age-matched nondiabetic controls underwent coronary artery ligation. One week later, the left ventricul ar end-diastolic pressure, systolic blood pressure, infarct size, and serum ANP levels did not differ significantly between the diabetic and nondiabetic rats. Compared with control animals without MI, the atria l ANP/beta-actin mRNA ratio in rats with MI was increased to 195% in d iabetic animals and 213% in nondiabetic animals. In the left ventricle , however, the ANP/beta-actin mRNA ratio in diabetic animals with MI w as increased to only 131% compared with control animals, whereas the c orresponding increase in nondiabetic animals was 240% (p<0.05). Thus, the modulation of ANP mRNA expression after MI was impaired in the lef t ventricle, but not in the atria, of diabetic rats. A reduced myocard ial expression of ANP could increase the morbidity and mortality assoc iated with cardiovascular disorders in patients with diabetes.