Endothelin B receptor dysfunction mediates elevated myogenic tone in cerebral arteries from aged male Fischer 344 rats

Abstract The human brain requires adequate cerebral blood flow to meet the high demand for nutrients and to clear waste products. With age, there is a chronic reduction in cerebral blood flow in small resistance arteries that can eventually limit proper brain function. The endothelin system is a key...
Ausführliche Beschreibung

Abstract The human brain requires adequate cerebral blood flow to meet the high demand for nutrients and to clear waste products. With age, there is a chronic reduction in cerebral blood flow in small resistance arteries that can eventually limit proper brain function. The endothelin system is a key mediator in the regulation of cerebral blood flow, but the contributions of its constituent receptors in the endothelial and vascular smooth muscle layers of cerebral arteries have not been well defined in the context of aging. We isolated posterior cerebral arteries from young and aged Fischer 344 rats, as well as $ ET_{B} $ receptor knock-out rats and mounted the vessels in plexiglass pressure myograph chambers to measure myogenic tone in response to increasing pressure and targeted pharmacological treatments. We used an $ ET_{A} $ receptor antagonist (BQ-123), an $ ET_{B} $ receptor antagonist (BQ-788), endothelin-1, an endothelin-1 synthesis inhibitor (phosphoramidon), and vessel denudation to dissect the roles of each receptor in aging vasculature. Aged rats exhibited a higher myogenic tone than young rats, and the tone was sensitive to the $ ET_{A} $ antagonist, BQ-123, but insensitive to the $ ET_{B} $ antagonist, BQ-788. By contrast, the tone in the vessels from young rats was raised by BQ-788 but unaffected by BQ-123. When the endothelial layer that is normally enriched with $ ET_{B1} $ receptors was removed from young vessels, myogenic tone increased. However, denudation of the endothelial layer did not influence vessels from aged animals. This indicated that endothelial $ ET_{B1} $ receptors were not functional in the vessels from aged rats. There was also an increase in $ ET_{A} $ receptor expression with age, whereas $ ET_{B} $ receptor expression remained constant between young and aged animals. These results demonstrate that in young vessels, $ ET_{B1} $ receptors maintain a lower myogenic tone, but in aged vessels, a loss of $ ET_{B} $ receptor activity allows $ ET_{A} $ receptors in vascular smooth muscle cells to raise myogenic tone. Our findings have potentially important clinical implications for treatments to improve cerebral perfusion in older adults with diseases characterized by reduced cerebral blood flow. Ausführliche Beschreibung

Autor*in:	Young, Alexander P. [verfasserIn] Zhu, Jiequan [verfasserIn] Bagher, Amina M. [verfasserIn] Denovan-Wright, Eileen M. [verfasserIn] Howlett, Susan E. [verfasserIn] Kelly, Melanie E.M. [verfasserIn]

Format:	E-Artikel
Sprache:	Englisch

Erschienen:	2021

Schlagwörter:	ET receptors Fischer 344 rats Myogenic tone Cerebral artery

Anmerkung:	© American Aging Association 2021

Übergeordnetes Werk:	Enthalten in: Age - New York, NY : Springer Science+Business Media, 1978, 43(2021), 3 vom: 05. Jan., Seite 1447-1463
Übergeordnetes Werk:	volume:43 ; year:2021 ; number:3 ; day:05 ; month:01 ; pages:1447-1463

Links:	Volltext

DOI / URN:	10.1007/s11357-020-00309-7

Katalog-ID:	SPR044262167