An improved method for the determination of the plasma volume with Evans Blue

A novel method to determine lean body water using localized skin biopsies: correlation between lean skin water and lean body water in an overhydration model

To determine the relationship between total body water (TBW) fraction and local water content measured in the skin (SW) this study assessed eight anesthetized piglets in an overhydration model. TBW was assessed by deuterium oxide dilution and body mass measurements taken throughout the experiments, and by whole body carcass analysis at the end of each experiment. Additionally, extracellular water and plasma volume were assessed using bromide dilution and Evan's blue dilution, respectively. SW was assessed by tissue biopsies taken at 60-min intervals throughout the experiment. Lean body water (LBW) fraction and lean skin water (LSW) fraction were assessed by extracting the fat from the carcass and biopsy samples. A correlation does exist between TBW fraction and SW fraction with r2=0.58 (P<0.05); however, the strongest correlation occurred between the LBW fraction and LSW fraction with r2=0.87 (P<0.05) and an SE of prediction of 0.77%. These data demonstrate that LSW gives an accurate and precise estimate of LBW and could therefore be used to determine the hydration index in appropriate research settings.

Blood volume and body fluid compartments in lambs with aortopulmonary left-to-right shunts

A left-to-right shunt is accompanied by an increased plasma and blood volume. Since this is likely realized through renin/aldosterone-mediated salt and water retention, other body fluid compartments may be changed too. Therefore, we studied blood volume and body fluid compartments by a single-injection, triple-indicator dilution technique in nine 8-wk-old lambs with an aortopulmonary left-to-right shunt (55 +/- 3% of left ventricular output; mean +/- SEM) and in 11 control lambs, 2.5 wk after surgery. Systemic blood flow was maintained at the same level as in control lambs, but the aortic pressure of the shunt lambs was lower. Blood volume in shunt lambs was larger than in control lambs (110 +/- 6 vs. 84 +/- 7 ml/kg, P < 0.001) through an increase in plasma volume, which correlated significantly with the magnitude of the left-to-right shunt (r = 0.81, P < 0.01). Red blood cell volume was equal to that of control lambs. Evidence was obtained that the increase in plasma volume was induced by a transient increase in renin (8.0 +/- 2.2 vs. 1.6 +/- 0.2 nmol.l-1.h-1; P < 0.02) and aldosterone (0.51 +/- 0.14 vs. 0.24 +/- 0.09 nmol/liter) concentrations. Interstitial water volume, however, was not significantly different from that in control lambs. The amount of intravascular protein was significantly higher than in control lambs (5.0 +/- 0.3 vs. 3.5 +/- 0.2 g/kg body mass, P < 0.001). There were no significant differences in intracellular and total body water volumes between the two groups. We conclude that the increased amount of intravascular protein confines the fluid retained by the kidneys to the vascular compartment.

Multiple disturbances of free fatty acid metabolism in noninsulin-dependent diabetes. Effect of oral hypoglycemic therapy

To assess the mechanisms for the elevation of free fatty acids in noninsulin-dependent diabetes, free fatty acid metabolism and lipid and carbohydrate oxidation were compared in 14 obese diabetic Pima Indians and in 13 age-, sex-, and weight-matched nondiabetics. The studies were repeated in 10 of the diabetics after 1 mo of oral hypoglycemic therapy. Fasting plasma glucose concentrations were elevated in diabetics (242 +/- 14 vs. 97 +/- 3 mg/dl, P less than 0.01) and decreased to 142 +/- 12 (P less than 0.01) after therapy. Fasting free fatty acid concentrations were elevated in diabetics (477 +/- 26 vs. 390 +/- 39 mumol/liter, P less than 0.01) and declined to normal values after therapy (336 +/- 32, P less than 0.01). Although free fatty acid transport rate was correlated with obesity (r = 0.75, P less than 0.001), the transport of free fatty acid was not higher in diabetics than in nondiabetics and did not change after therapy. On the other hand, the fractional catabolic rate for free fatty acid was significantly lower in untreated diabetics (0.55 +/- 0.04 vs. 0.71 +/- 0.06 min-1, P less than 0.05); it increased after therapy to 0.80 +/- 0.09 min-1, P less than 0.05, and was inversely correlated with fasting glucose (r = -0.52, P less than 0.01). In diabetics after therapy, lipid oxidation rates fell significantly (from 1.35 +/- 0.06 to 1.05 +/- 0.01 mg/min per kg fat-free mass, P less than 0.01), whereas carbohydrate oxidation increased (from 1.21 +/- 0.10 to 1.73 +/- 0.13 mg/min per kg fat-free mass, P less than 0.01); changes in lipid and carbohydrate oxidation were correlated (r = 0.72, P less than 0.02), and in all subjects lipid oxidation accounted for only approximately 40% of free fatty acid transport. The data suggest that in noninsulin-dependent diabetics, although free fatty acid production may be elevated because of obesity, the elevations in plasma free fatty acid concentrations are also a result of reduced removal, and fractional clearance of free fatty acid appears to be closely related to diabetic control. Furthermore, the increase in fractional clearance rate, despite a marked decrease in lipid oxidation, suggests that the clearance defect in the diabetics is due to an impairment in reesterification, which is restored after therapy.