Renin-angiotensin system and prostacyclin biosynthesis in streptozotocin diabetic rats

The relationship between the renin-angiotensin system (RAS) and prostacyclin (PGI 2) biosynthesis was studied in experimental diabetic rats. The group with diabetes induced by streptozotocin (STZ, 3.3 mmol/kg i.v.) showed prolonged hypertension, and plasma renin activity decreased markedly from 8.4 ± 0.7 to 2.4 ± 0.3 and 1.2 ± 0.3 ng angiotensin I/ml per h at 2 and 8 weeks after STZ treatment. Plasma PGI 2, determined as 6-keto-PGF 1α, decreased significantly at 8 weeks, with the values for the STZ-treated and control groups being 1490 ± 99 and 2210 ± 90 pg/ml, respectively. Significant suppression of renin release from renal cortical slices was observed at 8 weeks in the diabetic group, although no significant change was found in the renal renin content when compared with that of the controls. The release of PGI 2 from the renal medullary slices of the diabetic group was suppressed at 2 and 8 weeks, with the suppression in aorta and renal cortical slices being apparent only at 8 weeks. These results indicate that suppression of the RAS may be related to PGI 2 biosynthesis in diabetes mellitus.