Biomedical Engineering Application Brief

Pharmacology

The Problem

About half a million people suffer from heart attacks in this country every year. Another half-million have ischemic heart disease: disease in which the coronary artery is blocked, preventing proper supply of blood, and therefore of oxygen, to the heart. Dr. Jeffrey E. Byrne, of the cardiovascular pharmacology department at the Bristol-Myers Squibb Pharmaceutical Research Institute, studies how individual myocardial, or heart muscle, cells are affected by these problems. In particular, he studies the action potentials, or electrical currents, of individual cells from healthy and unhealthy hearts. His group develops and investigates medications to help hearts keep a steady beat.

Action Potential

Healthy myocardial cells undergo regular chemical changes which generate action potentials. Each voltage spike, caused by the movement of charged particles across the cell membrane, is one cell's idea of one heartbeat. The stronger and more regular a cell's action potentials are, the better it can keep a beat with all the cells in one area. This beat, however, can be disorganized if some cells are starved for oxygen. Dr. Byrne measures myocardial action potentials from healthy and diseased hearts to find out how oxygen loss affects the heartbeat and how drugs of different kinds help a heart maintain a steady beat despite oxygen loss. His team needs to be able to make hundreds of measurements of action potentials without disrupting a cell's beat, and to get visual representations of the voltage changes involved.