Vascular stasis, intestinal hemorrhage, and heightened vascular permeability complicate acute portal hypertension in cd39-null mice

Abstract

Vasoactive factors that regulate splanchnic hemodynamics include nitric oxide, catecholamines, and possibly extracellular nucleosides/nucleotides (adenosine, ATP). CD39/ectonucleoside triphosphate diphosphohydrolase-1 (NTPDase1) is the major vascular ectonucleotidase that hydrolyzes extracellular nucleotides. CD39 activity may be modulated by vascular injury, inflammation, and altered oxygen tension. Altered Cd39 expression by the murine hepatosplanchnic vasculature may impact hemodynamics and portal hypertension (PHT) in vivo. We noted that basal portal pressures (PPs) were comparable in wild-type and Cd39-null mice (n = 9). ATP infusions resulted in increments in PP in wild-type mice, but, in contrast, this significantly decreased in Cd39-null mice (n = 9) post-ATP in a nitric oxide-dependent manner. We then studied Cd39/NTPDase1 deletion in the regulation of portal hemodynamics, vascular integrity, and intestinal permeability in a murine model of PHT. Partial portal vein ligation (PPVL) was performed in Cd39-null (n = 44) and wild-type (n = 23) mice. Sequential measurements obtained after PPVL were indicative of comparable levels of PHT (ranges 14-29 mmHg) in both groups. There was one death in the wild-type group and eight in the Cd39-null group from intestinal bleeding (P = 0.024). Circulatory stasis in the absence of overt portal vein thrombosis, portal congestion, intestinal hemorrhage, and increased permeability were evident in all surviving Cd39-null mice. Deletion of Cd39 results in deleterious outcomes post-PPVL that are associated with significant microcirculatory derangements and major intestinal congestion with hemorrhage mimicking acute mesenteric occlusion. Absent Cd39/NTPDase1 and decreased generation of adenosine in the splanchnic circulation cause heightened vascular permeability and gastrointestinal hemorrhage in PPVL.

Fig. 1.

With portal pressure (PP) in quiescent state, baseline pressures were comparable in both wild-type and CD39-null mice. Mean PP before and after ATP infusion was 4.4 ± 0.8 mmHg and 5.4 ± 0.8 mmHg in wild-type and 4.9 ± 0.5 mmHg and 3.96 ± 0.2 mmHg in Cd39-null animals, respectively (P < 0.0001). In wild-type, N^ω-nitro-l-arginine (l-NNA) administration after ATP did not significantly alter PP, but PP transiently dropped after l-NNA in Cd39-null animals. Nitric oxide blockade preceding ATP administration in Cd39-null mice increased from 4.9 ± 0.5 mmHg to 5.4 ± 1.3 mmHg (P = 0.137).

Fig. 2.

Sequential PP measurements after partial portal vein ligation (PPVL) in wild-type and Cd39-null animals days 0–4. There were no significant differences in PP readings between the two groups. Median PP of +/+ was 3.9 ± 0.1 mmHg, and the median value of −/− was 4.2 ± 0.1 mmHg; P = 0.939 (top). The spleen/body ratio of wild-type and Cd39-null animals, days 0–4 after PPVL, was statistically and significantly higher (*P = <0.005) in the Cd39-null mice at day 4 (bottom).

Fig. 3.

Cumulative (Cum.) survival after PPVL in Cd39-null and wild-type animals. There was significantly increased mortality post-PPVL in Cd39 −/− animals compared with wild-type (P = 0.024).

Fig. 4.

A and B: substantive Cd39/ectonucleoside triphosphate diphosphohydrolase-1 (NTPDase1) normalized for GAPDH expression in mesenteric (top) pancreatic (bottom) tissue after PPVL in wild-type and Cd39-null animals. There was no expression in CD39-null animals. Asterisks denote statistically significant differences at P < 0.05. wt, wild-type; Ctrl, control; ko, knockout.

Fig. 5.

Severe congestion, edema, and tissue hemorrhage of the intestines in Cd39-null animals (right) compared with normal appearing intestines on wild-type animals (left).

Fig. 6.

Intestinal and vascular permeability changes with Evans blue infusion were significantly more pronounced in CD39-null than in wild-type animals. At day 4 there was a significant difference between wild-type 6.5 OD (optical density)/g and Cd39-null animals 9.0 OD/g, *P = 0.025.