On/Off Switches for Nitric Oxide Synthases

Richard C. Venema
rvenema@mail.mcg.edu

>On Fri Dec 11, Richard C. Venema wrote
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>>On Tue Dec 8, grover wrote
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>>>Dr. Venema:  These are very interesting results.  Do you think that there are ways to isolate these pools of endothelial cells which respond differently to various situations to study their properties?
>>>On Tue Dec 8, Richard C. Venema wrote
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>>>>On Fri Dec 4, grover wrote
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>>>>>Dr. Venema: Great presentation.  Hope you have fun at the meeting.  With so many different regulators of eNOS - I wonder if there is a hierarachy for regulation at different sites.
>>>>>Dr. Grover:  I believe there are different pools of eNOS in endothelial cells that are activated in different ways by different combinations of allosteric effectors.  This may explain why NO release in response to Ca2+ ionophore is much greater than that in response to bradykinin or other hormones.  NO release in response to shear stress is even greater still and can be up to 20 times greater than in response to a hormone agonist.
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>>>Dr. Grover:  I believe there are different pools of eNOS within the same cell.  We have found that eNOS is 10% cytosolic, 30% in caveolae, and 60% in Golgi.  These compartments can be separated by centrifugation on sucrose density gradients.  However, further subfractionation would be difficult.
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Dr. Grover, Here are some references that show Golgi localization of eNOS:
Morin et al. (1993) J. Neurosci. Res. 36, 272
Stanboli et al. (1994) Neurosci. Lett. 171, 209
O'Brien et al. (1995) Histochemistry 103, 221
Sessa et al. (1995) J. Biol. Chem. 270, 17641
Garcia-Cardena et al (1996) PNAS 93, 6448
Venema et al. (1997) BBRC 236, 155
Liu et al. (1997) J. Cell Biol. 137, 1525
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