In blood vessels, there is a close relationship between membrane potential and intracellular calcium, and between membrane potential and vascular diameter. Thus even small changes in membrane potential of vascular muscle produce significant changes in vascular tone. Opening or closure of potassium channels has important effects on membrane potential and thus vascular tone.
Studies utilizing pharmacological approaches, and more recently genetically altered mice, suggest that potassium channels play a major role in mediating microvascular dilatation in response to diverse stimuli. These stimuli include elevations in concentrations of extracellular potassium ion, receptor-mediated agonists (including calcitonin gene-related peptide, prostacyclin, and adenosine), second messengers (cAMP and cGMP), EDRFs, reactive oxygen species (hydrogen peroxide and superoxide anion), chemical stimuli (hypoxia, hypercapnia, acidosis), and calcium sparks.
Was this article helpful?
This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.