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

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.

Cannabinoid and lipid-mediated vasorelaxation in retinal microvasculature.

The endocannabinoid system plays a role in regulation of vasoactivity in the peripheral vasculature; however, little is known about its role in regulation of the CNS microvasculature. This study investigated the pharmacology of cannabinoids and cannabimimetic lipids in the retinal microvasculature, a CNS vascular bed that is autoregulated. Vessel diameter (edge detector) and calcium transients (fura-2) were recorded from segments of retinal microvasculature isolated from adult, male Fischer 344 rats.

Age-associated alterations in retinal arteriole reactivity to endothelin-1 differ between the sexes.

Endothelin-1 (ET-1) is a vasoconstrictor implicated in age-related retinal pathologies. This study determined whether responses to ET-1 differed in retinal arterioles isolated from adult (2-3 months) and aged (>20 months) Fischer 344 rats of both sexes. Risk factors for retinal disease (retinal perfusion pressure, intraocular pressure, blood glucose) were not affected by age.

Differential effects of docosahexaenoic acid on contractions and L-type Ca2+ current in adult cardiac myocytes.

Unlabelled: Beneficial effects of n-3 polyunsaturated fatty acids in Ca2+ overload have been attributed to blockade of L-type Ca2+ current (I(Ca-L)). However, cardiac contractions may be maintained despite block of I(Ca-L).

Objective: This study investigates the cellular basis by which docosahexaenoic acid (DHA), a representative n-3 polyunsaturated fatty acid, inhibits I(Ca-L) while preserving contraction.