COLLAGEN GELS POPULATED WITH RAT NEONATAL HEART-CELLS CAN BE USED FOROPTICAL-RECORDING OF RHYTHMIC CONTRACTIONS WHICH ALSO SHOW ECG-LIKE POTENTIALS

Neonatal heart cells populated collagen gels show rhythmic contraction s which can be recorded optically and electrically. Optical recordings revealed two populations of rhythmically contracting gels: 1) highly coherent contracting collagen gels with normally distributed contracti on interval times and contraction amplitudes, and 2) irregularly contr acting gels with a multi-modal distribution of contraction interval ti mes and amplitudes. The irregularly contracting gels were shown to be 'semi regular', which means that a short contraction interval was pref erentially followed by another short interval. The volume of the colla gen gel during the contraction decreased, and our calculations indicat e that the myocytes expel 3-10 times their own volume from the gel. Ch anges in electrical potential were observed depending on the location of the electrodes. These electrical, ECG-like changes in potential wer e maximal when one electrode was placed in the centre and the other at the edge of the gel. The results of this study indicate that myocyte- populated collagen gels are a very promising system for studies of ele ctrophysiology and coherent contractions.