[Use of magnetic tomography in cardiology. Introduction of a new method]. / Bruk av magnettomografi i kardiologien. Innføring i en ny metode.

Magnetic resonance imaging of the heart has already become an important tool in evaluating the cardiovascular system. This paper describes the basic principles of magnetic resonance imaging, the application of magnetic resonance imaging in the diagnosis of heart diseases, and the experience of using it in Trondheim since 1987. The paper is illustrated by several heart images from Trondheim.

A theory for the membrane potential of living cells.

We give an explicit formula for the membrane potential of cells in terms of the intracellular and extracellular ionic concentrations, and derive equations for the ionic currents that flow through channels, exchangers and electrogenic pumps. We demonstrate that the work done by the pumps equals the change in potential energy of the cell, plus the energy lost in downhill ionic fluxes through the channels and exchangers. The theory is illustrated in a simple model of spontaneously active cells in the cardiac pacemaker. The model predicts the experimentally observed intracellular ionic concentration of potassium, calcium and sodium. Likewise, the shapes of the simulated action potential and five membrane currents are in good agreement with experiment. We do not see any drift in the values of the concentrations in a long time simulation, and we obtain the same asymptotic values when starting from the full equilibrium situation with equal intracellular and extracellular ionic concentrations.