Bioenergetics and cell communication; cell uncoupling seen as a protective mechanism in cardiac muscle.

Differences in rate of ATP resynthesis between apposing heart cells were created by dialysing 2-4-dinitrophenol (0.01-0.05 mM) into just one cell of isolated heart cell pairs. When 0.01 mM of dinitrophenol was used the junctional conductance (gj) remained unchanged for at least 8 min if cell 1 (normal) was pulsed at low rate (0.04 Hz). The increment in rate of pulsing to 4 Hz caused a fast decrease (13%) of gj within 30 sec. This change in gj was spontaneously reversed. With 0.05 mM of dinitrophenol cell uncoupling was produced if cell 1 (normal) was stimulated at 4 Hz for 25-30 sec. Despite the suppression of electrical coupling (which was not reversed within 8 min.) no contracture or signs of deterioration of the experimental conditions were found. Cell uncoupling can be seen as a protective mechanism providing opportunity to energy-depleted cells to re-establish their ATP stores.