Ultrasonic bath depth control and regulation in single cell recordings.

Control of the bath depth is critical in many applications of the patch-clamp technique, particularly when the capacitance of cells is determined to assess secretion or transmitter release or in studies of ion currents sensitive to small changes in the hydrostatic pressure. We describe an inexpensive technique for tight control of the bath depth with the aid of a commercially available ultrasound sensor. The sensor continuously determines changes in the distance to the bath surface with a resolution of about 10 mum.