What is STEP and What is RAMP in electrohysiology protocol

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neurons
neurons's picture
What is STEP and What is RAMP in electrohysiology protocol

I am doing my Ph.D in Neuroscience(Electrophysiology), but my background is not in this area , I am using AXON instrument
so can anybody tell me in that when u design a protocol in the wave form option it says STEP or RAMP
what does it mean what exactly happens when u put step and when u put RAMP

how can one know that this is a suitable protocol for ur type of cells or ur specific conditions

If there is any very basic book which can clear my doubts then please let me know, like when one patch embryonic neurons and when u don't put the EGTA, or sodium what happens
like i want to know certain basic requirement as one has to add K+ to depolarize the membrane so how do u know what is function of all the component of ur extra and intra and why it is being used at particular concentration only

Fraser Moss
Fraser Moss's picture
Firstly some essential

Firstly some essential reading

The axon guide can be downloaded
here and has plenty of useful pointer for writing protocols

Also I frequently recommend this book as a plainly written guide for beginners

Patch Clamping: An Introductory Guide to Patch Clamp Electrophysiology
by Areles Molleman
# ISBN-10: 047148685X
# ISBN-13: 978-0471486855
here is the link to the book on
Amazon.com

RE the step vs ramp protocol question

Ramps have the advantage of generating current-voltage relations directly and very rapidly and might be considered suitable to study for a study of rapidly activating or time independent currents.

Step protocols measure the steady state current at a given voltage and depending on the duration of the step allow the investigator to also analyze the kinetics of the current at each voltage and view phenomena including inactivation, desensitization at a particular voltage

neurons
neurons's picture
thanks a lot it really

thanks a lot it really cleared my basic doubts

neurons
neurons's picture
FRASER MOSS

FRASER MOSS
Sir I have one more request if you can help me
in your published paper
Proc. Natl. Acad. Sci. USA
Vol. 95, pp. 8328–8333, July 1998
in MATERIALS AND METHODS It is mention as
The pharmacological sensitivities of
the 10–13 (a1A-2, a2bd, b4a), G1A1 (a1B-1, a2bd, b1b), C11D8(a1C-1, a2bd, b2e), 5D12–20 (a1D, a2bd, b3a), E52–3 (a1E-3, a2d,b1b), and E58–19 (a1E-3, a2d, b4a) cell lines, encoding P-Q, N,L, and R-type channels, respectively, have been reported (17).

what are this cell lines and sorry but the reference I am not able to get
Boot, J. R., O’Brien, A. & Tran, S. (1997) Brit. J. Pharmacol. 122,
Suppl. 1, 89P (abstr.).

If you still have soft copy of this refernce then please send it to me

Fraser Moss
Fraser Moss's picture
I doubt you will be able to

I doubt you will be able to acquire the cell lines as they were proprietary to SIBIA who had licensed them to Eli Lilly.

SIBIA were subsequently purchased by MERCK in 1999 (see http://findarticles.com/p/articles/mi_m0EIN/is_1999_Nov_12/ai_57532783) so you would have to come to a special arrangement with MERCK to have a remote chance of using them.

Brit J Pharmacol have the poster reference you are looking for available at http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1910415&pageindex=17#page

the PDF is available at http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1910415&blobtype=pdf

good luck