A pharmacological differentiation between postjunctional (AT(1A)) and prejunctional (AT(1B)) angiotensin II receptors in the rabbit aorta

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Guimaraes, S (Author) Other; Carneiro, C (Author) Other; Brandao, F (Author) Other; Pinheiro, H (Author) Other; Albino Teixeira, A (Author) FMUP; moura, d (Author) FMUP

Journal

Title: Naunyn-Schmiedeberg's Archives of Pharmacology

Vol. 370

Pages: 262-269

ISSN: 0028-1298

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 5 Citations

Scopus - 6 Citations

Other information

Authenticus ID: P-000-8CG

DOI: 10.1007/s00210-004-0977-7

Abstract (EN): The effects of angiotensin II and angiotensin III were compared at prejunctional and postjunctional AT(1) receptors of the rabbit thoracic aorta. Furthermore, the influence of PD123319, losartan and eprosartan on these effects was also compared. To study prejunctional effects, the tissues were preincubated with (H-3)-noradrenaline, superfused and electrically stimulated (1 Hz, 2 ms, 50 mA, 5 min). To study postjunctional effects, non-cumulative concentration-response curves were determined. Both angiotensin II and angiotensin III were more potent prejunctionally than postjunctionally. In the case of angiotensin II, the EC50 was 12 times lower at the prejunctional than at the postjunctional level, while that of angiotensin III was 30 times lower prejunctionally. Furthermore, whereas angiotensin II was about 33 times more potent than angiotensin III postjunctionally, it was only 12 times more potent than angiotensin III prejunctionally. Eprosartan did not differentiate between prejunctional and postjunctional effects of both angiotensins. In contrast, PD123319 and losartan did differentiate; however, whereas PD123319 concentration-dependently antagonised the facilitation of tritium release caused by angiotensin II and angiotensin III and had no influence on the contraction of the aortic rings elicited by the peptides, losartan did the opposite: it concentration-dependently antagonised the contractions caused by the peptides on the aortic rings and exerted no influence on the facilitatory effect of angiotensin II and angiotensin III. These results show that prejunctional. and postjunctional receptors for angiotensin II and angiotensin III are different and underline the hypothesis that postjunctional AT(1) receptors belong to the AT(1A) subtype, while prejunctional AT(1) receptors belong to the AT(1B) subtype.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8