Losartan attenuates endothelial hyperpermeability responses to VPF and high glucose but not angiotensin II

Rapid Improvement of Acute Pulmonary Edema with Angiotensin Converting Enzyme Inhibitor under Hemodialysis in a Patient with Renovascular Disease

A 71-year-old man with bilateral renovascular disease was admitted to Hamamatsu University hospital because of appetite loss and acute shortness of breath due to acute pulmonary edema (APE) with accelerated hypertension and renal failure. Hypertension and APE were controlled by an angiotensin converting enzyme inhibitor (ACEI) and four sessions of hemodialysis with reduction of 1.8 kg bodyweight. Renal function was later stabilized and the patient required no ACEI or hemodialysis. A trial of right renal angioplasty 1 month after admission failed and renal function deteriorated (serum creatinine 7.1 mg/dL) with accelerated hypertension, gain of bodyweight and APE. Even after four sessions of hemodialysis with adequate reduction of bodyweight, APE was not controlled, but it rapidly improved after administration of an ACEI, without major bodyweight change. As no apparent cardiac dysfunction was evident, APE might have been caused by a direct action of angiotensin II on hyperpermeability in pulmonary capillaries. Blocking of angiotensin II should be considered in such patients even after introduction of hemodialysis.

Protein kinase C-β inhibition and diabetic microangiopathy: effects on endothelial permeability responses in vitro

Protein kinase C (PKC)-beta and other PKC isozymes have been implicated in the loss of endothelial barrier function in diabetic microangiopathy. The effects of a PKC-beta-specific inhibitor, LY379196, on hyperpermeability responses to high-glucose, angiotensin II, alpha-thrombin and endothelin-1 were evaluated using an in vitro model of human pulmonary artery endothelial cell monolayers. LY379196 attenuated the increase in transendothelial albumin flux induced by glucose 40 mM (e.g. 411+/-160% [high-glucose] vs. 167+37% [high-glucose+LY379196], P<0.001) and angiotensin II 10 microM (e.g. 121+/-12% vs. 246+/-35%, P<0.01); endothelin-1 had no significant effect on monolayer permeability. LY379196 had no significant effect on the marked hyperpermeability response to alpha-thrombin 1 microM. Thus, two major pathways involved in vascular leakage in diabetic microangiopathy are amenable to therapeutic blockade by PKC-beta inhibition.

Rosiglitazone and pulmonary oedema: an acute dose-dependent effect on human endothelial cell permeability

AIMS/HYPOTHESIS

Peripheral and pulmonary oedema has emerged as the most common drug-related side effect of rosiglitazone in clinical practice, but the underlying mechanisms are not clear. Fluid retention and changes in vascular tone could contribute to oedema formation, but the interpretation of clinical and in vivo studies is particularly difficult and the direct effects of thiazolidinediones on endothelial barrier function have not been previously reported.

METHODS

Human pulmonary artery endothelial cells were seeded and grown on 0.4 microm collagen-coated filters to form a tight monolayer (transendothelial electrical resistance 9-11 ohms.cm(-2) after 2-3 days). Transendothelial albumin flux (expressed as the percentage clearance of albumin relative to control) was measured using Evans blue-labelled albumin after exposure to rosiglitazone 1-100 micromol/l for 1 h to 48 h, and after removal of drug from the monolayer.

RESULTS

Incubation of pulmonary artery endothelial cells with rosiglitazone for 4 h produced immediate concentration-dependent increases in transendothelial albumin flux: e.g., relative to control (100%), 113%+/-13% (1 micromol/l), 215%+/-37% (10 micromol/l, p=0.01) and 461%+/-96% (100 micromol/l, p=0.002) (n=12). There was no effect after 1 h. The acute hyperpermeability response to rosiglitazone, maximal after 4 h, was fully reversible after washing the monolayer. After incubation for 24 to 48 h the effect of rosiglitazone on pulmonary endothelial permeability tended to subside: e.g., 210%+/-59% (24 h) for rosiglitazone 100 micromol/l (p=0.06).

CONCLUSION/INTERPRETATION

Exposure to high-therapeutic concentrations of rosiglitazone causes a reversible fourfold increase in pulmonary endothelial permeability which could be clinically relevant especially at higher doses and at times of peak plasma drug concentration.