Cardiovascular responses in the diabetic rat

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.