CARDIOVASCULAR RESPONSES IN THE DIABETIC RAT

¹ Thorndike Memorial Laboratories, Boston University School of Medicine, Boston, MA, U.S.A.

Cardiac and regional haemodynamics have been studied in 12- and 15-week-old streptozotocin-diabetic rats and in non-diabetic controls. Reduced cardiac output has been found in the 15-week-old diabetic rats (64 ± 13 ml/min, mean ± S.D.), while 12-week-old diabetic rats expressed normal values (104 ± 25 ml/min, mean ± S.D.). Renal blood flows of 12- and 15-week-old diabetic rats (3·4 ± 1 ml/min. g and 3·7 ± 1 ml/min. g, mean ± S.D. respectively) were similarly decreased, when compared to those of non-diabetic rats (5·47 ± 1 ml/min. g). This finding could be only partly attributed to the increased plasma renin activity of the 12- and 15-week-old diabetic rats (16·6 ± 6 ng/ml. h and 19·3 ± 4 ng/ml. h respectively), which were higher than normal (4 ± 1 ng/ml. h). Otherwise the circulations of the brain, heart, gastrointestinal and musculocutaneous systems were similar in the diabetic and non-diabetic rats. In conclusion, while cardiac output was decreased only in the 15-week-old diabetic rats, renal perfusion was altered at an earlier stage of the diabetic process.