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.