MSCs constitute a population of multipotential cells giving rise to adipocytes, osteoblasts, chondrocytes, and vascularsmooth muscle-like hematopoietic supportive stromal cells. It remains unclear whether MSCs can be isolated from adult peripheral blood under stationary conditions and whether they can be mobilized in a way similar to hematopoietic stem cells. In this report, we show that MSCs are regularly observed in the circulating blood of rats and that the circulating MSC pool is consistently and dramatically increased (by almost 15-fold) when animals are exposed to chronic hypoxia. The immunophenotype and the adipocytic, osteoblastic, and chondrocytic differentiation potential of circulating MSCs were similar to those of bone marrow MSCs. Hypoxia-induced mobilization appears to be specific for MSCs since total circulating hematopoietic progenitor cells were not significantly increased. Our data provide an in vivo model amenable to analysis of MSC-mobilizing factors.

Abstract-An increased Ca2ϩ influx attributed to dihydropyridine-sensitive L-type Ca 2ϩ channels has been demonstrated in mesenteric vascular smooth muscle cells of spontaneously hypertensive rats (SHR). This study examined whether an upregulation of the pore-forming ␣ 1C subunit of the L-type Ca 2ϩ channel underlies this ionic defect. With the use of mesenteric arcade arteries from 12-to 16-week-old SHR and normotensive Wistar Kyoto (WKY) rats, reverse transcriptase-polymerase chain reaction demonstrated an increased level of amplified cDNA corresponding to the ␣ 1C subunit mRNA in the SHR arteries. Western blots confirmed that the increased mRNA expression was associated with a 3.4-fold increase in the immunoreactive signal of the ␣ 1C subunit protein in SHR compared with WKY mesenteric arteries, and immunocytochemistry confirmed this abnormality at the single-cell level. Finally, isolated mesenteric arteries from SHR were highly reactive to Bay K8644 and developed anomalous Ca 2ϩ -dependent tone, suggesting a functional role for ␣ 1C subunit upregulation in vascular hyperreactivity. To determine if these Ca 2ϩ channel abnormalities extended to the SHR skeletal muscle bed, we repeated a similar series of studies in WKY and SHR hind limb arteries. Skeletal muscle arteries from SHR also expressed higher levels of [1][2][3] Similarly, the arterioles of the mesenteric and skeletal muscle beds of SHR develop an abnormal Ca 2ϩ -dependent vascular tone and show increased myogenic responsiveness. 4 -6 Isolated mesenteric and femoral arteries of SHR also develop abnormal Ca 2ϩ -dependent tone, whereas similar arteries from WKY rats are quiescent. 7,8 In view of its central role in generating vascular tone, it is surprising that the mechanism of the elevated Ca 2ϩ influx in SHR VSMCs remains unclear. Some evidence suggests that VSMC membranes are depolarized in hypertension, resulting in the activation of L-type Ca 2ϩ channels. 9 Alternatively, excitatory stimuli including neurotransmitters and intracellular mediators may preferentially activate vascular L-type Ca 2ϩ channels during hypertension. 10,11 Recently, however, studies using mesenteric arteries as a model have shown that VSMCs of SHR, studied in patchclamp conditions that tightly control cell membrane potential and environment, still exhibit an enhanced voltage-gated Ca 2ϩ influx compared with WKY cells. Ohya et al 12 demonstrated a higher membrane density of L-type Ca 2ϩ current in mesenteric VSMC of 5-to 6-week-old SHR compared with agematched WKY rats, although density was normalized in SHR by 16 to 18 weeks of age. No differences in L-type Ca 2ϩ channel properties were detected between these preparations. In detailed studies, Cox and Lozinskaya 13,14 detected a higher density of L-type Ca 2ϩ current in mesenteric VSMC from 6-, 12-, and 20-week-old SHR and observed normal voltagedependent activation of the SHR Ca 2ϩ channel. Finally, single-channel analysis by Ohya and colleagues 15 in cell-

BackgroundPulmonary arterial hypertension (PAH) is a vasculopathy characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. This results in both increase in pulmonary arterial pressure and pulmonary vascular resistance. Recent studies have shown the implication of the signal transducer and activator of transcription 3 (STAT3)/bone morphogenetic protein receptor 2 (BMPR2)/peroxisome proliferator‐activated receptor gamma (PPARγ) in PAH. STAT3 activation induces BMPR2 downregulation, decreasing PPARγ, which both contribute to the proproliferative and antiapoptotic phenotype seen in PAH. In chondrocytes, activation of this axis has been attributed to the advanced glycation end‐products receptor (RAGE). As RAGE is one of the most upregulated proteins in PAH patients' lungs and a strong STAT3 activator, we hypothesized that by activating STAT3, RAGE induces BMPR2 and PPARγ downregulation, promoting PAH‐PASMC proliferation and resistance to apoptosis.Methods and ResultsIn vitro, using PASMCs isolated from PAH and healthy patients, we demonstrated that RAGE is overexpressed in PAH‐PASMC (6‐fold increase), thus inducing STAT3 activation (from 10% to 40% positive cells) and decrease in BMPR2 and PPARγ levels (>50% decrease). Pharmacological activation of RAGE in control cells by S100A4 recapitulates the PAH phenotype (increasing RAGE by 6‐fold, thus activating STAT3 and decreasing BMPR2 and PPARγ). In both conditions, this phenotype is totally reversed on RAGE inhibition. In vivo, RAGE inhibition in monocrotaline‐ and Sugen‐induced PAH demonstrates therapeutic effects characterized by PA pressure and right ventricular hypertrophy decrease (control rats have an mPAP around 15 mm Hg, PAH rats have an mPAP >40 mm Hg, and with RAGE inhibition, mPAP decreases to 20 and 28 mm Hg, respectively, in MCT and Sugen models). This was associated with significant improvement in lung perfusion and vascular remodeling due to decrease in proliferation (>50% decrease) and BMPR2/PPARγ axis restoration (increased by ≥60%).ConclusionWe have demonstrated the implications of RAGE in PAH etiology. Thus, RAGE constitutes a new attractive therapeutic target for PAH.

Since almost 60% of adults diagnosed with a müllerian duct cyst did not experience any cyst related symptoms or ejaculatory-fertility impairment, we recommend that investigation and/or treatment should only be done in symptomatic or infertile patients.

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These findings strongly suggest that our transobturator technique is highly accurate, reproducible and safe, and it does not require perioperative cystoscopy.

The cellular mechanisms mediating hypoxia-induced dilation of cerebral arteries have remained unknown, but may involve modulation of membrane ionic channels. The present study was designed to determine the effect of reduced partial pressure of O2, PO2, on the predominant K+ channel type recorded in cat cerebral arterial muscle cells, and on the diameter of pressurized cat cerebral arteries. A K(+)-selective single-channel current with a unitary slope conductance of 215 pS was recorded from excised inside-out patches of cat cerebral arterial muscle cells using symmetrical KCl (145 mM) solution. The open state probability (NPo) of this channel displayed a strong voltage dependence, was not affected by varying intracellular ATP concentration [(ATP]i) between 0 and 100 microM, but was significantly increased upon elevation of intracellular free Ca2+ concentration ([Ca2+]i). Low concentrations of external tetraethylammonium (0.1-3 mM) produced a concentration-dependent reduction of the unitary current amplitude of this channel. In cell-attached patches, where the resting membrane potential was set to zero with a high KCl solution, reduction of O2 from 21% to < 2% reversibly increased the NPo, mean open time, and event frequency of the Ca(2+)-sensitive, high-conductance single-channel K+ current recorded at a patch potential of +20 mV. A similar reduction in PO2 also produced a transient increase in the activity of the 215-pS K+ channel measured in excised inside-out patches bathed in symmetrical 145 mM KCl, an effect which was diminished, or not seen, during a second application of hypoxic superfusion. Hypoxia had no effect on [Ca2+]i or intracellular pH (pHi) of cat cerebral arterial muscle cells, as measured using Ca(2+)- or pH-sensitive fluorescent probes. Reduced PO2 caused a significant dilation of pressurized cerebral arterial segments, which was attenuated by pretreatment with 1 mM tetraethylammonium. These results suggest that reduced PO2 increases the activity of a high-conductance, Ca(2+)-sensitive K+ channel in cat cerebral arterial muscle cells, and that these effects are mediated by cytosolic events independent of changes in [Ca2+]i and pHi.

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