CARDIAC-HYPERTROPHY IN DIABETIC SPONTANEOUSLY HYPERTENSIVE RATS - ROLE OF ANGIOTENSIN-II

1. In the present study the role of angiotensin II (AngII) in the deve lopment of cardiac hypertrophy in diabetes combined with hypertension was investigated. 2. Diabetes was induced in 8-week-old male spontaneo usly hypertensive rats (SHR) by intravenous injection of streptozotoci n (45 mg/kg bodyweight), Diabetic SHR were treated with the angiotensi n-converting enzyme (ACE) inhibitor ramipril at a dose of 0.4 mg/kg pe r day. 3. Twelve weeks following the onset of diabetes, hearts were ar rested in diastole and were perfusion-fixed. The right ventricle and l eft ventricle plus septum were weighed and the volume of the ventricul ar walls was determined using the Cavalieri principle, 4. Induction of diabetes in SHR led to a significant reduction in bodyweight compared with non-diabetic control SHR and this was not affected by ramipril t reatment, The development of hypertension was not as great in diabetic SHR compared with controls, such that at 12 weeks following the onset of diabetes systolic blood pressures (SEP) averaged 191 +/- 3 and 230 +/- 4 mmHg in diabetic SHR and controls, respectively, Ramipril treat ment significantly lowered SEP in diabetic SHR, 5. The left ventricle plus septum volume:bodyweight ratio (LV vol:BW) was significantly high er in diabetic SHR compared with controls (3.83 +/- 0.19 and 3.26 +/- 0.16 mm(3)/g, respectively). Ramipril treatment did not affect growth of the left ventricle in diabetic SHR with the LV vol:BW ratio averagi ng 3.95 +/- 0.14 mm(3)/g, Similar trends on growth were observed in th e right ventricle,6. In conclusion, the development of cardiac hypertr ophy in diabetic SHR appears to occur by mechanisms independent of Ang II and the elevation of blood pressure.