Effect of colchicine on angiotensin receptors in rabbit aorta.

Colchicine (10(-5) M) significantly depressed the dose-response curve for angiotensin in isolated rabbit aortic strips. A lower maximal response was observed without apparent change in receptor affinity for angiotensin, as can be judged by unchanged ED50 values. Colchicine also diminished the dose-response curve for norepinephrine. The angiotensinase activity in cell membrane fraction and high-speed supernate was significantly inhibited. Colchicine did not change the specific receptor binding of radioactive angiotensin to either cell membrane fraction or supernate. It is concluded that colchicine possibly depresses the response to angiotensin through a mechanism involving a site beyond membrane receptors.