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ABSTRACT. Ischemia time during transplantation has greatly restricted the quality and utilization of grafts. To improve the quality of islet transplantation, adenosine was added into the University of Wisconsin (UW) pancreas perfusate to assess its effect on islet yield and function in porcine pancreas. Ten pancreata from donation after cardiac death pigs were obtained and randomly divided into two groups: control group (N = 5) with UW perfusion solution, and experimental group (N = 5) with adenosine-enriched UW perfusion solution. The yield and purity of the islet cells were counted after they were collected, purified, and stained with dithizone. Acridine orange/propidium iodide staining was applied to determine islet cell viability. Islet function was assessed by glucose stimulated insulin secretion assays, and released insulin was quantified by enzyme-linked immunosorbent assay. The metabolic substrates of the pancreas were analyzed by trace dialysis technology. We found that the addition of adenosine in UW perfusion solution significantly increased the yield, purity and viability of islet cells, as well as enhanced their insulin release. In addition, the levels of metabolic substrates, pyruvate and lactate, were significantly reduced. The addition of adenosine could effectively increase islet cell viability during mechanical perfusions, which may improve islet transplantation. This perfusion protocol may be clinically feasible, and should be considered in the clinical setting.

Patients with pulmonary arterial hypertension (PAH) often have significant right ventricular hypertrophy (RVH). PAH therapies include Endothelin−1 (ET−1) receptor inhibitors (ETRIs), which modestly improve functional capacity. The effects of ETRIs on the RV are unknown despite the fact that ETRIs were associated with increased mortality in early left ventricular failure trials. We hypothesized that the modest effects of ETRIs in PAH might be in part due to a negative inotropic effect in the RV, antagonizing their beneficial vasodilating and anti−proliferative effects in pulmonary vessels. We examined 28 surgical biopsies of patients with RVH (confirmed macroscopically at surgery and by pre−op ECHO) compared to 13 normal RV samples; and 23 rats with PAH (monocrotaline) and RVH (RV/LV+septum increase by 56.2±7.4%) vs 28 normal controls. In humans, confocal immunohistochemistry showed that in RVH, expression increased (p<0.01) for ET−Receptor−A (ETR−A) by 2.14X (in rats by 3.61X) and for ET−1 by 3.58X (in rats by 4.66X) over normal myocardium while ET Receptor−B levels were not different. qRT−PCR in laser−capture microdissected RV myocardium showed increased ETR−A mRNA in RVH versus normal RVs in patients (164.1±23.6%) and rats (202.4±16.5%), p<0.01 for both. In modified Langendorff perfusions ETRIs (BQ−123 and Bosentan 10−7−10−5M) decreased contractility in RVH (but not normal RV) by 32.2±8.3% (p<0.01) in a dose−dependent manner (p<0.01). Patients and rats with PAH have an increase in ETA receptors in RVH myocardium. This might be a compensatory mechanism to preserve RV contractility when the afterload increases and ETRIs might be inhibiting it, limiting their efficacy. Further studies are needed in patients with RVH (ex. congenital heart disease) and caution is needed interpreting data from clinical trials using ETRIs. Our results might not be applicable to patients with non−hypertrophied, dilated RVs. This abstract is funded by: None. Am J Respir Crit Care Med 179;2009:A4141 Internet address: www.atsjournals.org Online Abstracts Issue