PharmPK Discussion - Sampling from cardiac tissue

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On 19 Jan 2004 at 07:19:15, neeraj sikka (neerajsikka.-at-.yahoo.com) sent the message

hi all
i am doing a pk study in rats and i have developed my analytical method
with plasma processing volume of 200 ul. Now the question is while
doing an oral pk study can i take4 samples (each of 500 ul) from one
rat using cardiac sampling. Is there some limit of taking cardiac
samples from a single rat?
Kindly comment
neeraj sikka

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On 19 Jan 2004 at 14:24:56, "Ariff Ally" (Ariff_Ally.at.hc-sc.gc.ca) sent the message


Since you wish to sample 500 ul x 4 = 2000 ul, this is within the
compensatory system of the rat (large). The dilution of the blood (hct
is a reasonable measure ), as intravascular fluid is recruited to
restore blood volume may pose a problem if there is a short
intersampling interval. Blood should be withdrawn slowly, and the
amount must be limited  to less than 3-4 ml in a large adult rat,
unless euthanasia is planned. Also need to ensure that the needle
diameter is small enough so as to allow rapid platelet sealing of the
puncture site (decreased stroke volume due to leakage impacts all major
systems) and avoid any compounds which inhibit aggregation. A small
risk of impaling the coronary artery is a concern with this procedure.
Good luck.
Ariff Ally Ph.D
Head FREAS, Health Evaluation Division

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On 19 Jan 2004 at 18:27:37, manish issar (manish69.at.ufl.edu) sent the message


Hi Neeraj
There was a discussion on this issue in the past.  If you happen to
look back into the discussion archive i am sure you will get the answer
to your question. Hope this would help.
Best of luck
Manish Issar

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On 20 Jan 2004 at 08:48:24, "Nicholas Kerwin" (Nicholas.Kerwin.aaa.BioDynamics.co.uk) sent the message


Hi Neeraj,
Technically there should be no problem taking four cardiac puncture
samples from 1 rat, however you need to be careful wit the volumes you
take.
However, a much better way to sample in terms of both aniimal welfare
and number of samples you would be able to take would be to take samples
by puncture of the lateral tail vein.  There are many article about this
technique in the literature.  In our laboratory we are able to take 8 or
more samples by this technique (depending on the volume of each sample).
We have also further refined the method in that we now insert a
longdwell catheter into the tail and sample from that so reducing the
number of needle punctures to one.
Hope this is helpful.
Nick Kerwin

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