Ionophoric interaction with the myocyte sarcolemma : a new insight into the pathophysiology of degenerative myocardial disease.

A certain group of compounds often derived from microbes known as ionophores function as ion channels when incorporated in biological membranes. Different ionophores have a relative specificity for certain cations such as Ca2+ or K+. When such compounds are integrated in the cell membrane of a host cell a leakage of the ion in question is induced and the physiologic ion gradient will be dissipated. This will activate ion pumps at the expense of ATP in order to restore the physiologic ion gradient. This effect is seen for a number of different viruses including Coxsackie B3. Based on own experiments we suggest that this ionophoric effect is important in the pathophysiology of myocarditis. We have shown that mice with Coxsackie B3 myocarditis have low myocardial ATP and high ADP and AMP levels. This pattern of abnormal energy metabolism is also seen in patients with Syndrome X. It is suggested that the ECG and thallium perfusion scintigram suggestive of ischemia in such patients is rather due to the effect of an ionophore leading to an extracellular potassium shift.