Acute pancreatitis conditioned mesenteric lymph causes cardiac dysfunction in rats independent of hypotension.

BACKGROUND: Critical illness including severe acute pancreatitis is associated with the multiple organ dysfunction syndrome. The "gut-lymph" hypothesis states that multiple organ dysfunction syndrome is due to release of toxic factors from the intestine into the mesenteric lymph. The aims of this study were to determine the effect of normotensive acute pancreatitis conditioned mesenteric lymph on cardiac function and whether external drainage of mesenteric lymph would protect the heart. METHODS: Groups of normal rats and those with normotensive taurocholate induced acute pancreatitis, had either no lymphatic intervention or thoracic duct ligation and external drainage of mesenteric lymph. After 6 hours, the hearts were removed for ex vivo functional measurements, including cardiac output, ventricular contractility (+dP/dt), and relaxation (-dP/dt). In a second experiment, mesenteric lymph from normal rats and those with established acute pancreatitis was infused into ex vivo perfused normal working rat hearts to assess impact on cardiac function. Heart and lung tissues were collected for assessment of edema. RESULTS: Significant cardiac dysfunction, denoted by decreased cardiac output (21%), contractility (37%), relaxability (23%), and increased cardiac tissue edema (2-fold), developed in rats with established acute pancreatitis and no lymphatic intervention compared with the control group (all P < .05). Strikingly this cardiac dysfunction and edema was normalized in acute pancreatitis rats that had undergone prior thoracic duct ligation and external drainage of mesenteric lymph. In the second experiment, infusion of acute pancreatitis conditioned mesenteric lymph resulted in an immediate and significant similar magnitude decrease in of cardiac output (17%), contractility (22%), and relaxation (27%) compared with the infusion of normal lymph (all P <.05). CONCLUSION: Mesenteric lymph from normotensive acute pancreatitis animals caused significant cardiac dysfunction which could be prevented by thoracic duct ligation and external drainage of mesenteric lymph.

The diabetic rat kidney mediates inosituria and selective urinary partitioning of D-chiro-inositol.

Diabetic nephropathy is a serious complication of diabetes mellitus with a pressing need for effective metabolic markers to detect renal impairment. Of potential significance are the inositol compounds, myo-inositol (MI), and the less abundant stereoisomer, D-chiro-inositol (DCI), which are excreted at increased levels in the urine in diabetes mellitus, a phenomenon known as inosituria. There is also a selective urinary excretion of DCI compared to MI. As the biological origins of altered inositol metabolism in diabetes mellitus are unknown, the aim of this study was to determine whether the diabetic kidney was directly responsible. Kidneys isolated from four-week streptozotocin-induced diabetic rats were characterized by a 3-fold reduction in glomerular filtration rate (GFR) compared to matched non-diabetic kidneys. When perfused with fixed quantities of MI (50 µM) and DCI (5 µM) under normoglycemic conditions (5 mM glucose), GFR-normalized urinary excretion of MI was increased by 1.7-fold in diabetic vs. non-diabetic kidneys. By comparison, GFR-normalized urinary excretion of DCI was increased by 4-fold. Perfusion conditions replicating hyperglycemia (20 mM glucose) potentiated DCI but not MI urinary excretion in both non-diabetic and diabetic kidneys. Overall, there was a 2.4-fold increase in DCI urinary excretion compared to MI in diabetic kidneys that was independent of glucose ambience. This increased urinary excretion of DCI and MI in diabetic kidneys occurred despite increased renal expression of the inositol transporters, sodium myo-inositol transporter subtype 1 and 2 (SMIT1 and SMIT2). These findings show that the diabetic kidney primarily mediates inosituria and altered urinary partitioning of MI and DCI. Urinary inositol levels might therefore serve as an indicator of impaired renal function in diabetes mellitus with wider implications for monitoring chronic kidney disease.

Isolated perfused rat kidney: a technical update.

The isolated perfused kidney is commonly utilized as a screening tool for renal clearance and metabolism, and to correlate renal drug deposition to renal function. Here, we report on several aspects of this procedure that will facilitate a higher experimental success rate and lead to a reduction in animal use. First, we investigated the utility of inulin and creatinine as commonly used markers to measure glomerular filtration rate. For inulin, in the presence of either 20 mM glucose or 4.5% dextran in the buffer, significant interference was observed using an anthrone-based colorimetric assay. These findings suggest that caution needs to be exercised when using glucose or dextran and when inulin is quantitated using this method. Under these circumstances the use of alternative methods of inulin quantitation such as fluorescently tagged inulin is preferred. Second, we optimized bovine serum albumin (BSA) and BSA/dextran compositions that are routinely recommended as oncotic agents in the perfusion buffer and found that a 4% BSA/1.67% dextran composition had the best viability of kidney biomarkers in accordance with recommended threshold parameters. These considerations will be of particular relevance to researchers utilizing the isolated perfused kidney as a screening tool to measure renal biology and drug metabolism as well as applications to investigate diabetic nephropathy.