Mark Mattson mpm at
Thu Sep 1 15:41:58 EST 1994

: Hi, netters.
: A student just told me about results published in a paper in
: Journal of Neuroscience, where the authors report measuring
: cGMP with a microdialysis technique in the brain. They measured
: cGMP after infusion of NMDA, antagonists of NMDA channel, NO synthase
: inhibitors, nitric oxide donors, etc, to show that stimulation of NMDA
: receptor in the brain produced cGMP as a consequence of nitric oxide
: signalling.
: My question is: Does it not sound strange measuring cGMP outside living cells?
: Shouldn't cGMP be found only inside the cells, except following cell disruption
: or membrane damage? Is it only my proverbial ignorance on these issues?
: I'll appreciate any comment, and I can even tolerate a little abuse
: should the question be totally stupid.
: Thanks

It's a very appropriate question, but the answer is you are wrong.   
(Biology, the discipline where a priori means nothing.)  There is 
substantial evidence that cGMP and cAMP are released from cells; in some
systems, as much as two-thirds of the cGMP synthesized gets out.
Sort of makes you wonder, doesn't it.

I don't have refs at hand, but I know Ron Fiscus has published some 
studies on cyclic nucleotides released from cultured cells.

Best regards,
Steven W. Barger, Ph.D.
Sanders-Brown Center on Aging

More information about the Cellbiol mailing list