Headspace gas chromatography (HSGC) was used to measure the concentrations of acetone in samples of venous whole blood from drunk drivers (n = 500), hospital outpatients with type-I diabetes mellitus (n = 250), and healthy blood donors (n = 288). The standard deviation (SD) of blood-acetone determination by HSGC was 0.048 mg/L at a mean concentration of 2.34 mg/L (2.1%). The concentration of acetone in blood did not change significantly when the samples were stored at 4 degrees C for eight days. The ratio of the concentrations of acetone in plasma and whole blood was 1.23:1 (SD 0.229, n = 22). The frequency distributions of blood-acetone concentrations were markedly skewed to the right. The median concentration of acetone in blood from drunk drivers was 2.03 mg/L and the 2.5 and 97.5 percentiles were 0.80 and 12.8 mg/L, respectively. In patients with type-I diabetes mellitus, the median blood-acetone concentration was 1.90 mg/L and the 2.5 and 97.5 percentiles were 0.40 and 11.1 mg/L, respectively. In healthy blood donors, the median blood-acetone level was 1.26 mg/L and the 2.5 and 97.5 percentiles were 0.37 and 4.69 mg/L, respectively. The concentrations of acetone in blood did not differ appreciably among these three groups of subjects.

BackgroundThe stability of ethanol was investigated in blood specimens in glass or plastic evacuated tubes after storage in a refrigerator at 4 °C for up to 12 months.MethodsSterile blood, from a local hospital, was divided into 50 mL portions and spiked with aqueous ethanol (10% w/v) to give target concentrations of 0.20, 1.00, 2.00 and 3.00 g/L. Ethanol was determined in blood by headspace gas chromatography (HS-GC) with an analytical imprecision of <3% (coefficient of variation, CV%). Aliquots of blood were re-analysed after 2, 7, 14, 28, 91, 182 and 364 days of storage at 4 °C.ResultsThe standard deviation (SD) of analysis by HS-GC was 0.0059 g/L at 0.20 g/L and 0.0342 g/L at 3.00 g/L, corresponding to CVs of 2.9% and 1.1%, respectively. The decreases in blood ethanol content were analytically significant after 14–28 days of storage for both glass and plastic tubes The mean (lowest and highest) loss of ethanol after 12 months storage was 0.111 g/L (0.084–0.129 g/L) for glass tubes and 0.112 g/L (0.088–0.140 g/L) for plastic tubes. The corresponding percentage losses of ethanol were 43–45% at a starting concentration of 0.20 g/L and 3.9–4.1% at 3.00 g/L.ConclusionThe concentration of ethanol in blood gradually decreases during storage at 4 °C. After 12 months storage the absolute decrease in concentration was ~0.11 g/L when the starting concentration ranged from 0.20 to 3.0 g/L. Decreases in ethanol content were the same for specimens kept in glass or plastic evacuated tubes.

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There was an age-related reduction of the sensitivity of rat and guinea-pig isolated tracheal smooth muscles to stimulation of ,8-adrenoceptors, but the ability of tracheal smooth muscle to relax to isoprenaline was not completely lost. Fleisch, Maling & Brodie (1970) and Fleisch (1971) have demonstrated what they called 'ageing' of the ,I-adrenoceptor activity in rat, rabbit and guinea-pig aortas. It was shown that the ability of isolated aortas to relax to isoprenaline decreased with increasing age and was completely lost when rats were 3-6 months old and when rabbits were 2 years old.We have now determined the effect of age on /8-adrenoceptor activity in the tracheal muscle of rats and guinea-pigs.Methods.-Sprague-Dawley rats and guinea-pigs of either sex were used. The rats used were 45 days (145-155 g), 98 days (250-300 g) and 210 days (400-450 g) old, while the guinea-pigs were 3 weeks (160-170 g), 4 months (570-640 g) and 27 months (900-1,100 g) old.Tracheal chains were prepared and mounted in a modified Krebs solution containing (mM): Na+ 137-47; Ca2+ 2-49; K+ 593; Mg2+ 119; Cl-134-11; HCO3-15-48; H2PO4 1 19 and glucose 11-5. The solution was aerated with 95% 02 and 5% CO2 and the contractions were measured isometrically with a Grass FT 03B force transducer and recorded on a Grass polygraph. The rat and guinea-pig tracheal chains were contracted with carbachol 1 ,ug/ml and 0 1 ,ug/ml respectively and were relaxed by (-)-isoprenaline that was added to the bath fluid every 5 min in increasing concentrations.Results.--Tracheal chains from guineapigs were more sensitive to isoprenaline than tracheal chains from rats. There were age-related reductions in sensitivity to isoprenaline in tracheal smooth muscle from both guinea-pigs and rats during the first months of life (Fig. la & b). Thereafter the reduction in sensitivity was not significant. Thus the differences in sensitivity to isoprenaline between 45 and 98 day old rats, and between 18 and 120 day old guinea-pigs were significant (P<0 001 and P<001, respectively), but the differences between 98 and 210 day old rats and between 120 and 800 day old guinea-pigs were not (P>0 05). A reduced /l-adrenoceptor activity was still present in the older animals.Discussion.-The 'ageing' of the tracheal /3-adrenoceptor activity occurred during the first months of life of the animals used in the present investigation. It might therefore be better to use the term 'maturation' instead of 'ageing'.In contrast to the rat aorta (Fleisch et al., 1970;Fleisch, 1971) the /3-adrenoceptor activity was not completely lost in any of the tracheal chain preparations investigated. Fleisch et al. (1970) reported a significantly decreased relaxant response to isoprenaline 0 03 mg/ml in tracheas from rats 275-420 days old as compared with tracheas from rats 41-60 days old. The relaxant responses to higher concentrations of isoprenaline (01-1l0 mg/ml) were not significantly decreased with increasing age in their experiments, nor was there a clear dose-response relationship. In our expe...

The relationship between cyclic AMP levels and mechanical activity after exposure to isoprenaline was studied in tracheal smooth muscle. It was found that the basal cyclic AMP content decreased with age. The relaxing effects of isoprenaline, theophylline and papaverine were tested on muscles contracted by histamine, acetylcholine or carbacholine. Isoprenaline completely relaxed histamine contracted tracheas, but not those contracted by acetylcholine or carbacholine. Theophylline and papaverine completely relaxed the tracheas irrespective of whether the contracting agent was histamine, acetylcholine or carbacholine. Isoprenaline increased the cyclic AMP content of bovine trachea; this effect was stronger in muscles with spontaneous tension than in histamine contracted muscles. In muscles contracted by carbachol, isoprenaline increased the cyclic AMP level after 5 min. The correlations between the changes in the cyclic AMP levels and the tension in tracheal smooth muscle support the hypothesis that this nucleotide plays a role in the relaxation process.

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