1990 Volume 5 Issue 6 Pages 925-952
The distribution, metabolism and excretion of 3H-angiotensin II (3H-A II) were investigated after intravenous administration to rats.
1. The radioactivity in the plasma, after bolus intravenous administration to male and female rats, declined with half-lives of 1.0 and 1.1 min, respectively, within first 2.5 min. The radioactivity increased once again within 10 ?? 20 min after administration and thereafter decreased again with half-lives of 3.0 and 1.1 day, respectively.
The radioactivity of AII, AIII, Tyr and p-HPPA declined rapidly with half-lives of 8.5, 7.9 sec and 5.2 and 5.9 min, respectively.
2. The radioactivity in the plasma of male and female rats increased slowly during intravenous infusion, and afterwards declined with half-lives of 2.2 and 2.4 min, respectively, within 2.5min after the infusion was stopped, and thereafter once again increased within 10 min after the end of infusion and finally a gradual decrease was observed.
The concentrations of AII, AIII, Tyr and p-HPPA declined rapidly after the end of infusion similarly as after bolus administration.
3. The radioactivity in the tissues reached maximum within 24 hr after infusion. The highest level of radioactivity was noted in the pancreas and followed by the liver, bone marrow, stomach, kidney, duodenum, adrenal gland and pituitary gland. The disappearance of radioactivity from each tissue was very slow.
4. After the end of the infusion, radioactive substances in the plasma consisted not only AII and its metabolites but also were found in volatile (9.1%) and protein fractions (25.3%). Volatile and protein fractions increased with time. The concentrations of A II in the liver and kidney were somewhat high, while only a minor amount of A II was noted in the lung and heart.
5. After intravenous infusion to male rats, the excretion of radioactivity in the urine, feces and expired air was 24.3, 9.8 and 5.8% of the dose, respectively. Within 168 hr after the end of infusion, the residual radioactivity in the carcass accounted for 56.6% of the dose. The profile of excretion in female rats was similar to that in male rats. The biliary excretion of radioactivity accounted for 15. 2% of the dose after 48 hr infusion. No AII and AIII were noted in the urine, feces and bile. Volatile fraction was mainly excreted, while the excretion of Tyr and p-HPPA was minor.
