Tezosentan reduces the microvascular filtration coefficient in isolated lungs from rats subjected to cecum ligation and puncture.
BACKGROUND
We recently demonstrated that the non-selective endothelin-1 (ET-1) receptor blocker tezosentan antagonizes ovine acute lung injury (ALI) following infusion of endotoxin or ET-1 by reducing the enhanced lung microvascular pressure, although we could not exclude the possibility of a simultaneous decline in microvascular permeability. In the present study, our aim was to find out if tezosentan reverses the rise in microvascular filtration coefficient (Kfc) in rat lungs that have been isolated and perfused 12 h after cecum ligation and puncture (CLP) or infusion of ET-1.


METHODS
Wistar rats (n = 42) were subjected to CLP. Postoperatively, rats were randomized to a CLP group (n = 7) and a CLP + tezosentan group (n = 7); the latter received tezosentan 30 mg/kg. A sham-operated group (n = 5) underwent laparotomy without CLP. Twelve hours postoperatively, the lungs were isolated and perfused with blood from similarly treated rats that also were used to assess plasma concentration of ET-1 and protein kinase Calpha (PKCalpha) in lung tissue. Additionally, isolated blood perfused lungs from healthy rats were randomized to a control group (n = 8), an ET-1 group (n = 7) subjected to pulmonary arterial injection of ET-1 10 nM, and an ET-1 + tezosentan group (n = 7) that received tezosentan 30 mg/kg. All lung preparations received papaverine 0.1 microg/kg added to the perfusate for vasoplegia. Pulmonary hemodynamic variables, Kfc and lung compliance (CL) were assessed.


RESULTS
After CLP, the plasma concentration of ET-1 increased. Papaverine abolished the vasoconstrictor response to ET-1 and the pulmonary vascular pressures remained close to baseline throughout the experiments. Both CLP and injection of ET-1 caused significant changes in Kfc and CL that were prevented in tezosentan-treated rats. Compared to sham-operated animals, CLP increased the content of PKCalpha by 50% and 70% in the cytosolic and the membrane fractions of lung tissue homogenates, respectively. Tezosentan prevented the upregulation of PKCalpha in the membrane fraction.


CONCLUSIONS
In rat lungs isolated and perfused after CLP, tezosentan precludes both the increase in Kfc and the upregulation of PKCalpha in the membrane fraction of lung tissue.
Kuklin
Vladimir
V
Department of Anaesthesiology, Faculty of Medicine, University of Tromsø, MH Building, 9037 Tromsø, Norway. Vladimir.Kuklin@unn.no
Sovershaev
Mikhail
M
Andreasen
Thomas
T
Skogen
Vegard
V
Ytrehus
Kirsti
K
Bjertnaes
Lars
L
D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D002432:Cecum / Q000293:injuries; D004195:Disease Models, Animal; D065130:Endothelin A Receptor Antagonists; D066298:In Vitro Techniques; D008026:Ligation; D008168:Lung / Q000098:blood supply* / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000378:metabolism; D011654:Pulmonary Edema / Q000378:metabolism; D011677:Punctures; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000097:blood; D012016:Reference Values; D013777:Tetrazoles / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D065130:Endothelin A Receptor Antagonists; D011725:Pyridines; D044022:Receptor, Endothelin A; D013777:Tetrazoles; D014665:Vasodilator Agents; C120582:tezosentan; D051571:Protein Kinase C-alpha