The effect of pentobarbital anaesthesia upon the extracellular fluid volume in the dog, studied by continuous infusion and single injection methods

The effects of sevoflurane anesthesia on insulin secretion and glucose metabolism in pigs

We investigated the effects of two different concentrations of sevoflurane, 0.4 minimum alveolar anesthetic concentration (MAC) and 1.0 MAC, on insulin secretion before, during, and after sevoflurane anesthesia using three successive intravenous glucose tolerance tests (IVGTT) in pigs with indwelling catheters. We also investigated changes in the levels of plasma glucose, catecholamines (epinephrine [E], norepinephrine [NE]), and cortisol (Cor). The pigs were grouped as awake, 0.4 MAC, or 1.0 MAC. Sevoflurane decreased the ratio of insulin/glucose (INS/GLU) in the basal condition (P < 0.05 awake versus 1.0 MAC) and during IVGTT (P < 0.01 awake versus 1.0 MAC and 0.4 MAC). These decreases were quickly reversible (control levels were regained within 2 h of the end of anesthesia), were probably dose-related, appeared not to be mediated by E, NE, or Cor. In addition, the INS/GLU ratio 2.5-4 h after the end of anesthesia was significantly higher in the anesthetized groups than in the awake group. We conclude that sevoflurane anesthesia has a rapidly reversible inhibitory effect on basal and glucose-stimulated insulin secretion, as do other inhaled anesthetics, and might induce insulin resistance.

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.

The extrarenal effects of aldosterone on the distribution of extracellular fluid in conscious adrenalectomized-nephrectomized rats

In order to examine the extrarenal roles of aldosterone in cardiovascular homeostasis, the present study compared blood pressure, extracellular fluid volume (ECFV) and plasma volume (PV) in the three following groups: 10 nephrectomized (NX) rats, 10 nephrectomized-adrenalectomized (NX-AX) rats, and 10 NX-AX and aldosterone-treated (NX-AX-A) rats. Two-hundred and fifty micrograms of aldosterone, mixed with sesame oil, was given subcutaneously in the NX-AX-A rats. Mean arterial pressure (MAP) was recorded through previously implanted carotid catheters. ECFV and PV were measured using 35S-Na2SO4 and 131I-RISA, respectively, 24 h after the operation. These measurements were performed in an unanesthetized and unrestricted condition. MAP gradually increased in the NX group, while a gradual decrease was observed in the other groups. However, MAP was significantly higher in the NX-AX-A group than in the NX-AX group 6 h after the operation and thereafter. Changes in body weight were comparable in the three groups 24 h after the operation. ECFV and PV were both reduced in the NX-AX and the NX-AX-A groups as compared to the NX group (P less than 0.001 NX-AX vs NX, and P less than 0.05 and P less than 0.025 NX-AX-A vs NX, respectively). Although ECFV was comparable in the NX-AX and the NX-AX-A groups, PV was significantly greater in the NX-AX-A group than in the NX-AX group (P less than 0.05). There was a significant positive correlation between MAP and PV in the rats as a whole (r = 0.68, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Composition of postnatal weight loss and subsequent weight gain in small for dates newborn infants

Using a sucrose and deuterium oxide dilution technique body water compartments and solids were serially determined in small for dates newborn infants at birth, at the moment of maximum postnatal weight loss and on recovery of birth weight. Compositions of weight loss and subsequent weight gain were calculated from the differences in body water compartments and solids between the first and the second and the second and the third study, respectively. Birth weight of the infants was 1.55 +/- 0.46 kg (mean +/- SD) (N = 7), gestational age was 35.7 +/- 3.1 weeks. Results show that despite changes in extra- and intracellular water volumes during weight loss, total body water volume and solids per unit of body weight remained remarkably constant throughout the study. Compositions of weight loss and subsequent weight gain were similar to body composition. This suggests that in small for dates newborn infants postnatal weight loss is the result of catabolism rather than dehydration and subsequent weight gain is the result of growth rather than rehydration.

Simultaneous determination of dimethadione and trimethadione by infrared-spectrometry: application for mean intracellular pH measurement

A simple infrared-spectrometric method for the simultaneous determination of dimethadione and trimethadione in plasma is described. The method is based on the absorption band of the carbonyl group for trimethadione at the wavenumber of 1740 cm-1 and for dimethadione at the wavenumber of 1770 cm-1. The accuracy and precision of the method are excellent; at a dimethadione and trimethadione concentration of 0.5 mmol X 1(-1) the coefficient of variation for the determination of both compounds is less than 1%, which is better than that for the ultraviolet spectrometric or gas-liquid chromatographic methods. The method can be used for the determination of the ratio trimethadione/dimethadione in the clinical setting as a sensitive check of the patient's adherence to therapy. It can also be used for the determination of dimethadione as an indicator for the mean body intracellular pH.

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

A new method for the spectrophotometric determination of Evans Blue in plasma is presented. The method is based on the precipitation of the non-albumin fraction of the plasma proteins with polyethylene glycol, in order to eliminate the variable background absorption of plasma at the wavelength of maximum absorbance of Evans Blue. The accuracy and precision of the method is excellent: at an Evans Blue concentration in plasma of 5 mg . 1(-1) the coefficient of variation of the method is less than 1%. Five different procedures currently in use for the calculation of the plasma volume from the amount of indicator injected and the concentration at zero time (c0) were compared. Extrapolation to zero time of the early part (10 to 60 min) of the log concentration vs time curve turned out to the the best method for the calculation of c0, and hence yields the best estimate of the plasma volume.

Infrared-spectrometric determination of D2O in biological fluids. Reappraisal of the method and application to the measurement of total body water and daily water turnover in the dog

The determination of D2) in biological fluids by means of infrared spectrometry was reinvestigated. When the temperature of a solution, containing D2O in the range from natural abundance to 5 ml . 1-1 increases, its absorbance decreases and the wavenumber of maximum absorption shifts to a higher value. Both changes are linearly related to the change in temperature. Storage for 17 d in either glass or polyethylene tubes does not affect the D2O concentration. Purification of biological fluids by vacuum-sublimation removes all substances which also absorb at the O-D vibration band and the recovery of D2O from plasma and urine is complete. The partition ratio of D2O between plasma water and red cell water equals unity, and the same holds for plasma water and urine water over a wide range of urine flows and osmolalities. The arterial and urinary disappearance curves of D2O, measured over several days, both permit the calculation of the total amount of body water (Vbw), the daily water turn-over (F) and the half-time of water in the body (t1