The exposure vessel as a factor in ultrasonically-induced mammalian cell lysis--II. An explanation of the need to rotate exposure tubes.

This paper is an attempt to explain the need to rotate a polystyrene tube containing a cell suspension in order to obtain cell lysis. Calculations, based on known physical laws, were performed in order to determine the important forces on cells and bubbles and the movements and interactions which these forces are likely to cause. These calculations support the following conclusions: (1) in the absence of rotation, cells and bubbles larger than resonance size are trapped at pressure minima while bubbles smaller than resonance size are trapped at pressure maxima, (2) at 1 W/cm2 with rotation, lysis is caused by cells sweeping through arrays of trapped small bubbles, (3) at higher intensities lysis is caused by both trapped and non-trapped small bubbles.