Angiotensin receptors from rat liver, brain and pituitary gland. Expression of two subtypes in Xenopus oocytes

Bernard Cantau (1) , Sylvain Bartolami (2) , Pierre P Baskevitch (1) , Frank Desarnaud (1) , Daniele Chicot (1) , Serge Jard (1)

1 CCIPE - Centre CNRS-INSERM de Pharmacologie Endocrinologie
2 MMDN - Mécanismes moléculaires dans les démences neurodégénératives

Xenopus laevis oocytes were used to express angiotensin receptors encoded by mRNAs extracted from rat liver, adenohypophysis and brain. Groups of ten mRNA-injected oocytes were loaded with 45Ca2+ and the responsiveness to angiotensin II (A II) and related molecules tested by monitoring 45Ca2+ outflux. A II and angiotensin III (A III) induced a marked and transient increase in 45Ca2+ outflux from mRNA, but not from control, water-injected, oocytes. The increase over basal value of 45Ca2+ outflux during a 5 min application period of A II or A III was used as a response index. Observed responses were of high magnitude, reproducible and dose-dependent. For these reasons, mRNA-injected oocytes constitute a valuable system for investigating the pharmacological properties of angiotensin receptors from tissues of different origin under experimental conditions which eliminate tissue-specific interference which might be encountered in classical binding studies on acellular preparations. We demonstrate a fairly good parallelism between the relative potencies of A I, A II and A III in eliciting an increase in 45Ca2+ outflux from liver and adenohypophyseal mRNA-injected oocytes and the relative affinities of these peptides for binding to liver or adenohypophyseal membranes (A II greater than A III much greater than A I). The predominant receptor subtype expressed by brain mRNA discriminated very poorly between A II and A III, whereas angiotensin receptors expressed by liver or adenohypophyseal mRNA discriminated between AII and AIII very efficiently.

Domaines: Biologie cellulaire

Bernard Cantau, Sylvain Bartolami, Pierre P Baskevitch, Frank Desarnaud, Daniele Chicot, et al.. Angiotensin receptors from rat liver, brain and pituitary gland. Expression of two subtypes in Xenopus oocytes. Biochemical Journal, 1991, 277 (3), pp.729-733. ⟨10.1042/bj2770729⟩. ⟨hal-02156384⟩