PMID- 12049652
OWN - NLM
STAT- MEDLINE
DCOM- 20020815
LR  - 20181113
IS  - 0264-6021 (Print)
IS  - 1470-8728 (Electronic)
IS  - 0264-6021 (Linking)
VI  - 364
IP  - Pt 3
DP  - 2002 Jun 15
TI  - Desensitization of endothelial nitric oxide synthase by receptor agonists.
PG  - 863-8
AB  - Stimulation of endothelial cells with receptor agonists leads to an activation of 
      endothelial nitric oxide synthase (eNOS) that only lasts for a short duration. A 
      more prolonged effect, however, is observed in response to non-receptor agonists, 
      such as Ca2+ ionophores or thapsigargin (TG). To investigate the molecular 
      mechanisms underlying the rapid deactivation of eNOS after stimulation with 
      receptor agonists, we measured the time courses of eNOS activation and 
      intracellular free Ca2+ concentration ([Ca2+]i) in response to bradykinin (BK) 
      and ATP. Incubation of porcine aortic endothelial cells with BK (1 microM) in the 
      presence of 3 mM extracellular Ca2+ increased [Ca2+]i from 110 to 350 nM and 
      enhanced the rate of l-[3H]citrulline formation from 0.1 to 5 fmol/min. In the 
      absence of extracellular Ca2+, the BK-induced increase in [Ca2+]i was only 
      marginal (from 30 to 110 nM) and not sufficient to activate eNOS. When Ca(2+) 
      (final concentration 3 mM) was added 10 min after BK, [Ca2+]i increased to 330 nM 
      within 3 min, but interestingly, formation of l-[3H]citrulline was not 
      detectable. A similar phenomenon was observed with ATP, but not with Ca2+ 
      ionophores or TG. This indicates that stimulation of endothelial cells with 
      receptor agonists leads to desensitization of eNOS, which renders the enzyme 
      insensitive to activation by subsequent increases in [Ca2+]i. However, when ATP 
      was added to BK-pretreated cells or, conversely, BK to ATP-pretreated cells, 
      activation of eNOS was comparable with that of untreated cells, suggesting that 
      BK and ATP affect different pools of eNOS. The desensitization of eNOS was 
      reversible, since removal of ATP or BK from the incubation buffer restored the 
      response to the respective agonist within 20 min. In addition to the transient 
      Ca2+ signal, desensitization of eNOS may represent a further mechanism by which 
      endothelial cells rapidly terminate receptor-dependent NO formation.
FAU - Wagner, Sabine
AU  - Wagner S
AD  - Institut fur Pharmakologie und Toxikologie, Karl-Franzens-Universitat Graz, 
      Universitatsplatz 2, A-8010 Graz, Austria.
FAU - Groschner, Klaus
AU  - Groschner K
FAU - Mayer, Bernd
AU  - Mayer B
FAU - Schmidt, Kurt
AU  - Schmidt K
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - Biochem J
JT  - The Biochemical journal
JID - 2984726R
RN  - 67526-95-8 (Thapsigargin)
RN  - EC 1.14.13.39 (Nitric Oxide Synthase)
RN  - EC 1.14.13.39 (Nitric Oxide Synthase Type III)
RN  - S8TIM42R2W (Bradykinin)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Aorta
MH  - Bradykinin/pharmacology
MH  - Calcium/metabolism
MH  - Endothelium, Vascular/*enzymology
MH  - Enzyme Activation
MH  - Nitric Oxide Synthase/*metabolism
MH  - Nitric Oxide Synthase Type III
MH  - Swine
MH  - Thapsigargin/pharmacology
PMC - PMC1222637
EDAT- 2002/06/07 10:00
MHDA- 2002/08/16 10:01
PMCR- 2002/12/15
CRDT- 2002/06/07 10:00
PHST- 2002/06/07 10:00 [pubmed]
PHST- 2002/08/16 10:01 [medline]
PHST- 2002/06/07 10:00 [entrez]
PHST- 2002/12/15 00:00 [pmc-release]
AID - BJ20011178 [pii]
AID - 10.1042/BJ20011178 [doi]
PST - ppublish
SO  - Biochem J. 2002 Jun 15;364(Pt 3):863-8. doi: 10.1042/BJ20011178.