space-clamp cardiomyocites

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Kiril Hristov
Kiril  Hristov's picture
space-clamp cardiomyocites

I am working on a new project and really need your help. I am studying mouse ventricular cardiomyocytes by using patch-clamp.I am trying to record sodium current in these cells. Because cardiomyocytes are large cells, there is a “space-clamp” problem which is especially important when relatively fast Na+ current is recorded. My question is how “space-clamp” problem can be addressed when Na+ current is recorded with conventional whole cell patch clamp? Should I compensate the series resistance by using “prediction correction” function? Can you please recommend protocols/articles which explain this problem in detail (particularly for cardyomyocites)? I truly appreciate your help. Thanks!

Fraser Moss
Fraser Moss's picture
Space clamp issues

Reduce the external sodium concentration from ~140 mM to 50 mM. This will reduce your peak currents and improve control of the clamp.however, remember that decreasing [Na+]o will alter the sodium channel's slow inactivation behavior (Townsend and Horn, J Gen Physiol 110:23, 1997)http://www.ncbi.nlm.nih.gov/pubmed/?term=9234168 

Kiril Hristov
Kiril  Hristov's picture
Space clamp issues

Thank you for your help and I really appretiate your response.  I agree that reduction of external Na+ will result of more acurate measurments of the Na+ peak current. However my question is would that be enaugh to resolve the problem with space-clamp and series resistance compentation since cardiomyocites are relatively large cells (cell capacitance more than 100 pF)?