The vascular-disrupting agent, combretastatin-A4-phosphate, enhances neurogenic vasoconstriction in rat small arteries.

Combretastatin-A4-phosphate (CA4P/CA4), an anti-cancer drug, induces tumour hypoxia by destabilizing the cytoskeleton in tumour endothelial cells. Hypertensive side effects have been observed. We hypothesized that CA4P/CA4 lead to endothelial dysfunction followed by increased vasoconstriction.

Pulmonary pressure reduction attenuates expression of proteins identified by lung proteomic profiling in pulmonary hypertensive rats.

The present study was designed to analyze protein expression in lungs from pulmonary hypertensive rats in order to identify novel signaling pathways. This was achieved by proteomic studies in which proteins from lung homogenates from hypoxic were compared to normoxic rats. The expression of these proteins was then investigated in lungs from hypoxic rats treated with either an activator of soluble guanylyl cyclase, BAY 412272, or an inhibitor of phosphodiesterase type 5, sildenafil.

BAY 41-2272 inhibits the development of chronic hypoxic pulmonary hypertension in rats.

The present study investigated whether BAY 41-2272(5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine), a novel pyrazolopyridine that activates guanylyl cyclase and sensitizes the enzyme towards nitric oxide (NO), inhibits the development of pulmonary hypertension. BAY 41-2272 (1 or 10 mg/kg/day) was administered intraperitoneally, and sildenafil (25 mg/kg/day), an inhibitor phosphodiesterase type 5, was given in the drinking water to rats kept under chronic hypobaric hypoxia for two weeks. Right ventricular systolic pressure and hypertrophy, degree of muscularization and relaxation of pulmonary arteries were measured, and immunoblotting was performed.

Proteomics reveals lowering oxygen alters cytoskeletal and endoplasmatic stress proteins in human endothelial cells.

A proteomic approach was applied to explore the signalling pathways elicited by lowering O(2) in endothelial cells. Endothelial cells isolated from native umbilical cords were subjected to 21, 5, or 1% O(2) for 24 h. 2-D PAGE was performed and candidate proteins were identified using LC-MS/MS.

Diminished NO release in chronic hypoxic human endothelial cells.

The present study addressed whether chronic hypoxia is associated with reduced nitric oxide (NO) release due to decreased activation of endothelial NO synthase (eNOS). Primary cultures of endothelial cells from human umbilical veins (HUVECs) were used and exposed to different oxygen levels for 24 h, after which NO release, intracellular calcium, and eNOS activity and phosphorylation were measured after 24 h. Direct measurements using a NO microsensor showed that in contrast to 1-h exposure to 5% and 1% oxygen (acute hypoxia), histamine-evoked (10 microM) NO release from endothelial cells exposed to 5% and 1% oxygen for 24 h (chronic hypoxia) was reduced by, respectively, 58% and 40%.

MAP kinases and heat shock-induced hormesis in human fibroblasts during serial passaging in vitro.

Adult human skin fibroblasts were exposed repeatedly to 41 degrees C or 42 degrees C heat shock (HS) for 1 h twice a week during serial passaging throughout their replicative life span. On the basis of longevity curves, cell size, and morphology, we observed that repeated mild heat shock (RMHS) at 41, degrees C had strong anti-aging hormetic effects, including 20% extension of cellular longevity. The basal levels of the MAP kinases JNK1, JNK2, and p38 increased during serial passaging, while that of ERK2 decreased.

Molecular mechanisms of anti-aging hormetic effects of mild heat stress on human cells.

In a series of experimental studies we have shown that repetitive mild heat stress has anti-aging hormetic effects on growth and various other cellular and biochemical characteristics of human skin fibroblasts undergoing aging in vitro. We have reported the hormetic effects of repeated challenge at the levels of maintenance of stress protein profile; reduction in the accumulation of oxidatively and glycoxidatively damaged proteins; stimulation of the proteasomal activities for the degradation of abnormal proteins; improved cellular resistance to ethanol, hydrogenperoxide, and ultraviolet-B rays; and enhanced levels of various antioxidant enzymes. We are now undertaking a detailed analysis of the signal transduction pathways to determine alterations in the phosphorylation and dephosphorylation states of extracellular signal-related kinase, c-Jun terminal kinase and p38 MAP-kinases as a measure of cellular responsiveness to mild and severe heat stress.

Pressure-induced activation of extracellular signal-regulated kinase 1/2 in small arteries.

Extracellular signal-regulated kinase 1/2 (ERK1/2) may play a central signaling role in vascular remodeling. We investigated a possible combined role for the renin-angiotensin system and platelet-derived growth factor beta-receptor (PDGF-beta-R) in pressure-induced ERK1/2 activation in intact rat mesenteric small arteries. In an organ culture model, vessels were pressurized (70 mm Hg) for 1 hour plus a 5-minute intervention period.