The vasoregulatory role of endothelium derived nitric oxide during pulsatile cardiopulmonary bypass.
The role of pulsatile flow as a physiologic stimulus for endothelium mediated vasoregulation is poorly understood. Furthermore, non pulsatile flow, which is associated with increased vascular resistance and end-organ failure, has been demonstrated to lead to a decrease in nitric oxide (NO) production in vitro. Anesthetized pigs (23.4 +/- 0.3 kg) were placed on cardiopulmonary bypass using either non pulsatile or pulsatile perfusion for 60 min. In both groups, animals were maintained with a constant mean aortic flow (1.0-1.3 L/min). Serum samples obtained during bypass were assayed for the stable end-products of NO (nitrate [NO3-] and nitrite [NO2-]) by a method based on the Greiss reaction. Systemic vascular resistance was higher after 60 min in the non pulsatile (3712.5 +/- 481.2 dyne sec cm(-5)) vs the pulsatile group (2672.6 +/- 427.0 dyne sec cm(-5)), but not statistically significant (p > .05). However, NO production was decreased in the non pulsatile flow group (27 +/- 6%) vs the pulsatile flow group (14 +/- 5%) at a statistically significant level (p < .005). The results suggest that non pulsatile flow is associated with diminished endothelial shear stress and a reduction in endothelial nitric oxide production. This may contribute to the detrimental physiologic effects observed in prolonged non pulsatile flow states.
Macha
M
M
Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15219, USA.
Yamazaki
K
K
Gordon
L M
LM
Watach
M J
MJ
Konishi
H
H
Billiar
T R
TR
Borovetz
H S
HS
Kormos
R L
RL
Griffith
B P
BP
Hattler
B G
BG
D000818:Animals; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000379:methods*; D005069:Evaluation Studies as Topic; D005260:Female; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000502:physiology*; D009573:Nitrites / Q000097:blood; D011673:Pulsatile Flow; D013552:Swine; D014655:Vascular Resistance / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide