Pulmonary endothelial dysfunction after cardiopulmonary bypass in neonatal pigs.
BACKGROUND
In neonatal pigs cardiopulmonary bypass (CPB) is associated with endothelial dysfunction in isolated large pulmonary arteries. It is, however, of great importance if this functional change extends to the small pulmonary resistance arteries, which are the key regulators of pulmonary flow and pressure. The aim of this study was to assess changes in pulmonary microvascular function after CPB using a clinically relevant pediatric procedure.


METHODS
From three groups of neonatal pigs (CPB-, sham- and control group) pulmonary resistance arteries and systemic resistance arteries (from skeletal muscle) were isolated and mounted as ring preparations in wire myographs. Vessel diameters were less than 500 microm. Concentration-response curves were constructed for norepinephrine (NA), vasopressin (Vp), and the thromboxane A2-analog U46619, while the endothelium-dependent and -independent vasodilator functions were assessed as responses to acetylcholine and nitric oxide (NO).


RESULTS
Maximum pulmonary vasodilator response to acetylcholine was attenuated after CPB compared with sham-operated and control animals (P=0.04). NO-induced relaxation, and contractile responses to NA, Vp, and U46619 were not influenced by CPB. In systemic arteries no changes in contractile or relaxant responses were seen after CPB.


CONCLUSIONS
CPB seems to induce pulmonary endothelial dysfunction in pulmonary but not peripheral resistance arteries in neonatal piglets.
The Research Laboratory, Department of Obstetrics and Gynecology, Skejby Hospital, Aarhus University Hospital, Denmark. mgk-njh@dadlnet.dk
M
M
Glavind-Kristensen
V
V
Brix-Christensen
E
E
Toennesen
H B
HB
Ravn
A
A
Forman
K
K
Sorensen
V E
VE
Hjortdal
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D066298:In Vitro Techniques; D008833:Microcirculation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000503:physiopathology; D009569:Nitric Oxide / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000503:physiopathology*; D013552:Swine; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014667:Vasopressins; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine; D009638:Norepinephrine