Angiotensin II desensitization and Ca2+and Na+fluxes in vascular smooth muscle cells

✍ Scribed by J. Aboulafia; M. E. M. Oshiro; T. Feres; S. I. Shimuta; A. C. M. Paiva

• Publisher: Springer
• Year: 1989
• Tongue: English
• Weight: 536 KB
• Volume: 415
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00370597

✦ Synopsis

The role of ion fluxes in angiotensin II (AII) desensitization (tachyphylaxis) was investigated by studying Na + and Ca 2+ translocation in cultured vascular smooth muscle cells from the rat aorta. The effects of AII were compared to those of [1-sarcosine]-AII (Sarl-AII), an analogue which also induces tachyphylaxis, and [2-1ysine]-AII (LysZ-AII), an analogue that does not show this property. Maximally effective concentrations of the three peptides induced a rapid and transient increase in r efflux, a rapid and sustained decrease in total cell Ca 2 + and an increased Na + permeability. Repeated treatments, at short intervals, with either of the three peptides abolished the effect on Ca 2+ efflux, and this desensitization was slowly reversible. A 30-rain rest period was sufficient for full recovery of the response of cells that were desensitized by Lys 2-AII, whereas the recovery from AII or SarX-AII-desensitization was still not complete after 60 min. Our results suggest that the difference in the behaviour of the "tachyphylactic" AII and Sarl-AII and the "nontachyphylactic" LysZ-AII lays not in the production of different signals upon binding to the receptor, but in a difference in the hormone-receptor interaction itself.