AIM: To study the effects of hypoxia on the vasoconstrictive response
and the angiotensin II (Ang II) content and its receptor. METHODS: Hyp
oxia was induced in isolated aorta of guinea pig by gassing N-2. The v
asoconstrictive response of aorta to Ang II was recorded. Ang II conte
nt and its receptor were measured by radioimmuoassay. RESULTS: Ang 3-3
000 nmol L(-1) increased the contractile response of aorta. Hypoxia am
plified 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 acti
on of Ang Il by hypoxia is due to the increase in the angiotensin rece
ptor density, but not associated with the changes in the Ang II conten
t in hypoxic aorta of guinea pig.