Microinjection experts; help me out please!

[Brad Doble]

I am trying to inject cultured neonatal rat cardiac myocytes, and have a
problem with the microinjection pipette surging forward when I press the
inject button (often leading to ruined pipettes!).  This happens even when
the injection pressure (as displayed on the LED readout of the injector)
is only 1 psi.  Does anyone know what might be going wrong?   I am using a
fluorescent dye to monitor the delivery of the injectant and thus, know
that the 1 micrometer diameter tips of the pipettes are not clogged.

Any feedback would be greatly appreciated.

Thanks in advance,

Brad

-- 
Brad  Doble                    umdoble at mail.cc.umanitoba.ca   
                                  or:  bradd at sbrc.umanitoba.ca
Department of Physiology, University of Manitoba