1. The effects of angiotensin II on glomerular filtration rate and renal plasma flow were studied in surgically instrumented conscious control and cirrhotic rats. In addition, angiotensin II binding and the contractile response to angiotensin II were studied in glomeruli isolated from cirrhotic and control rats.
2. Cirrhotic rats had a higher glomerular filtration rate and a higher renal plasma flow than control animals. A non-pressor dose of angiotensin II induced small but significant decreases in glomerular filtration rate and renal plasma flow in both control and cirrhotic rats, the effect on renal plasma flow being the most pronounced.
3. Plasma renin and aldosterone concentrations were similar in control and cirrhotic rats.
4. The cross-sectional area of glomeruli from cirrhotic rats was 42% greater than that of glomeruli from control animals. Angiotensin II (10−9 mol/l) decreased the cross-sectional area of glomeruli from control animals by 6.4 ± 0.9% and of glomeruli from cirrhotic rats by 6.6 ± 0.8% (P = not significant for comparison between control and cirrhotic animals).
5. There were no differences between control and cirrhotic rats in the affinity of angiotensin II for its glomerular receptors. However, the angiotensin II receptor density was higher in cirrhotic than in control rats, thereby producing an increased total angiotensin II binding in cirrhotic rats.
6. Since no functional differences between control and cirrhotic animals were present in the response to angiotensin II, even though angiotensin II binding was increased, a post-receptor blockade of the angiotensin II signal could be present in cirrhotic rats.
