EFFECT OF HYPOXIA ON ANGIOTENSIN-II CONTENT AND ITS RECEPTOR IN GUINEA-PIG AORTA

AIM: To study the effects of hypoxia on the vasoconstrictive response and the angiotensin II (Ang II) content and its receptor. METHODS: Hypoxia was induced in isolated aorta of guinea pig by gassing N-2. The vasoconstrictive response of aorta to Ang II was recorded. Ang II content and its receptor were measured by radioimmuoassay. RESULTS: Ang 3-3000 nmol L(-1) increased the contractile response of aorta. Hypoxia amplified the vasoconstrictve effect of Ang II. The concentration of Ang II were 44+/-24 and 50+/-17 pg/g wet wt (n = 10), respectively in non-hypoxic and hypoxic aortae. The receptor density in non-hypoxic aorta was 17 +/- 3 fmol mg(-1), and that in hypoxia was 33 +/- 5 fmol mg(-1) (P < 0.01). CONCLUSION: The enhancement of the vasoconstrictive action of Ang Il by hypoxia is due to the increase in the angiotensin receptor density, but not associated with the changes in the Ang II content in hypoxic aorta of guinea pig.