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  • Spring 2008 - Issue Number 70
  • Spring 2008 - Issue Number 70

Below are the feature articles from Physiology News Issue 70, Spring 2008.

To read the full articles please download the issue.

  • Features

Selectivity: a sticky affair?

In analogy to some ionic channels, substrate selectivity in ion-coupled cotransporters appears to imply a low flux rate. However, in the presence of potassium the hornworm KAAT1 transporter reconciles selectivity and high transport rates, writes Antonio Peres (below)
  • Features

Insight into how the human retina obtains its need of vitamin B1

The retina has a substantial need for a variety of nutrients, including vitamin B1. This vitamin is involved in a variety of metabolic reactions and, thus, is essential for normal functions and well-being of the retina. Hamid Said (below) and colleagues examined how human retinal epithelial cells transport the vitamin, how the transport process is regulated, and what happens when clinical mutations in a thiamin transporter (that occur in the genetic disorder thiamine-responsive megaloblastic anemia) affect the ability of this membrane protein to function as a transporter of the vitamin
  • Features

Cold facts about AMPK in fat
  • Features

Lack of a role for arterial chemoreceptors in the breakpoint of breath-holding

Oxygen levels in the blood influence breath-hold duration, yet the peripheral chemoreceptors that detect arterial hypoxia appear to have little or no role in determining the breakpoint of breath-holding. Debate about this paradox may have eclipsed another important feature of the breakpoint mechanism
  • Features

A starring role for astrocytes

Recent evidence continues to re-cast the role of astrocytes in brain function. Astrocytes now appear to express a rich repertoire of signalling mechanisms, can respond to neuronal signals and rapidly signal back to neurons. The recent work of Stephen Traynelis and his colleagues has further emphasized the ability of astrocytic receptors to control excitatory synaptic transmission. Thus these cells have emerged as active participants in brain function
  • Features

Modifying the excitability of motor cortex with direct current stimulation
  • Features

Exercise-induced adaptations in tendon tissue

Training induces changes in the mechanical and biochemical characteristics of tendon tissue. What mechanisms are involved and are these changes in proportion to skeletal muscle hypertrophy?
  • Features

Coupling or not coupling of mitochondria to Ca2+ sources in neurones. Soma and neurites differ

Bioluminescence imaging of aequorin targeted to mitochondria shows that these organelles are closely coupled to the endoplasmic reticulum in the soma but not in the neurites of sympathetic neurones. This functional organization could contribute to generate spatial differences in neuronal Ca2+ signals

  • Features

Breaking the barrier; the role of actin filaments in somato/dendritic peptide release

In many cells actin filaments are organised in a dense web beneath the plasma membrane and can be transiently depolymerised in response to stimulation, suggesting that actin filaments provide a barrier for vesicles to access sites of release

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