MECHANICAL-PROPERTIES OF ADULT FELINE VENTRICULAR MYOCYTES IN CULTURE

The contractile and electrophysiological properties of cultured adult feline ventricular myocytes were studied. Cells were field stimulated and contraction was measured using a video-based edge detector. The magnitude of contraction decreased by 36% and the rate of contraction decreased by 52% 2 h after the cells were plated on laminin-coated cover slips. The magnitude and rate of contraction then remained stable for 1 wk. The duration of contraction prolonged and a second component to the twitch frequently, but not invariably, developed after 5 days in culture. This was associated with prolongation of the action potential duration. After 7 days in culture, cells could be divided into two groups based on resting membrane potential. Norepinephrine increased the magnitude of contraction for 5 days after plating. Cultured ventricular myocytes became unresponsive to the effects of norepinephrine after 7 days. Adult cardiac myocytes maintained in primary culture continue to respond to field stimulation and retain many contractile properties for up to 7 days; however, the functional characteristics of these cells do not remain uniform during this time period.