Regulation of Coronary Blood Flow

The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017

Refractions: (tele)vision and the (trans)formation and (trans)mission of the culture landscape

The manner in which landscapes are technologically transmitted and taken up elsewhere is often treated as an unproblematic, literal transfer of artefacts and philosophies. But interpreting any vestige of culture taken from television requires recognising selections and transformations taking place in the act of reception. Traditional notions of centres and margins are refuted when the televisual is properly acknowledged, explicated here through Heidegger's presentation of technology as a mode of revealing. Within the televisual landscape, infotainment programmes promote a required level of expertise for structuring and maintaining the domestic garden, and are explored here through Gadamer's consideration of the role of the 'expert'. Playing with the idea of refraction, as it might stand for the transformative character of transmission and reception through television of the culture of landscape, I recognise that television too has its landscape and is itself a culture