Effects of storage time and freezing temperature on clinical chemical parameters from canine serum and heparinized plasma

To assess changes in 24 blood constituents in frozen serum and heparinized plasma, blood samples were drawn from 10 clinically normal German Shepherd army dogs. The storage characteristics of nine enzymes (ALP, ALT, amylase, AST, CK, GGT, GLDH, LDH, lipase), and 15 metabolites and minerals (albumin, bile acids, bilirubin, calcium, cholesterol, creatinine, fructosamine, glucose, magnesium, phosphate, potassium, protein, sodium, triglycerides, urea) were studied. Parallel samples of serum and heparinized plasma were stored for 90 and 240 days at two different storage temperatures, -200 degrees C and -700 degrees C. Sixteen of the 24 analytes (ALP, ALT, amylase, AST, CK, GGT, GLDH, LDH, bile acids, calcium, cholesterol, creatinine, fructosamine, magnesium, phosphate, urea) showed statistically significant (p < 0.05) changes during the storage period related to storage time, storage temperature, and sample type. Seven of the analytes (amylase, GGT, GLDH, LDH, bile acids, fructosamine, magnesium) showed changes of possible clinical importance with mean differences from baseline larger than 20% for the enzymes and 10% for the metabolites and minerals during the storage periods.     

Relationship between separation time of plasma from heparinized whole blood on plasma biochemical analytes of loggerhead sea turtles (Caretta caretta)

Concentrations and activities of selected biochemicals of loggerhead sea turtles (Caretta caretta) were determined for plasma that was separated from whole blood samples that were kept up to 96 hr post collection (PC) in a refrigerator. Blood samples collected from seven juvenile captive loggerhead sea turtles were added to tubes containing lithium heparin and were placed on ice. Equal amounts of anticoagulated whole blood from the lithium heparin tubes were then aliquoted into plastic tubes and stored as whole blood under refrigeration until they were centrifuged at 0, 4, 24, 48, and 96 hr PC. Plasma was removed and the analytes that were measured were alkaline phosphatase (ALP), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), creatine kinase (CK), sodium, chloride, potassium, magnesium, calcium, phosphorus, cholesterol, glucose, urea nitrogen, uric acid, total protein, albumin, and globulin. Compared with values at 0 time, the only analyte to be significantly different at 24 hr PC was GGT (activity decreased by 25%). Compared with values at 0 time, significant differences at 96 hr PC were only seen in AST (2% increase), GGT (25% decrease), glucose (7% decrease), and uric acid (25% increase). Although a statistically significant difference was found in concentrations of phosphorus and cholesterol over time by repeated measures analysis of variance (ANOVA), the follow-up multiple comparison procedure could not define the specific time points at which significant differences occurred. For all other analytes, significant differences over the time course of the study were not found. In these instances, the power of the ANOVA was sufficient (> or = 0.80) to detect any arithmetic differences of a clinically relevant magnitude. Although plasma should be separated from the cellular component of blood as soon as possible PC, in a field situation in which a centrifuge is unavailable, samples can be stored in a portable cooler up to 24 hr without appreciable change in select biochemical analytes.     

Serum constituents analyses in dairy cows: effects of duration and temperature of the storage of clotted blood

We studied the effects of storage time and temperature of clotted whole blood on the amounts of 17 analytes in bovine blood serum. Serum separated after blood was allowed to stand for 2, 4, 6, 12 and 24h at room temperature or on ice. Results obtained for phosphorous, magnesium, urea, cholesterol, beta-hydroxybutyrate (BHBA), triglyceride, albumin, total protein and gamma-glutamyletransferase (GGT) were not influenced by storage at room temperature or on ice for as long as 24h. Duration of the clotted whole blood storage had a significant effect on calcium, glucose concentrations, creatine kinase (CK) and aspartate aminotransferase (AST) activities and temperature had a significant effect on glucose, non-esterified fatty acids, CK and bilirubin concentrations.     

Concentrations of total proteins and albumins, and AST, AP, CK and GGT activities in the blood serum Boer and Saanen goats during puerperium

The metabolism of proteins in the blood serum in Boer and Saanen goats was investigated during puerperium. Twenty Boer goats (10 primiparous and 10 pluriparous) and 10 Saanen goats (five primiparous and five pluriparous) between 2 and 5 years of age were used in this research. Blood for analysis was taken every fourth day from day 3 until day 40 post-partum. Blood samples were collected by jugular puncture. In the obtained blood serum, the concentration of total proteins (PT) and albumin (ALB), and the activity of enzymes aspartate aminotransferase (AST) [the Enzyme Commission number (EC number) 2. 6. 1. 1.], gamma-glutamyltransferase (GGT) (EC 2. 3. 2. 2.), creatine kinase (CK) (EC 2. 7. 3. 2.) and alkaline phosphatase (AP) (EC 3. 1. 3. 1.) were determined by spectrophotometry. These parameters were in physiological ranges in Boer goats and in Saanen goats, without significant differences according to number of kids per doe. According to the research results of the blood serum in goats during puerperium, there were no significant differences in the concentration of ALB. Boer goats had significant higher (p < 0.05) concentration of PT and enzyme activity of AP, CK and GGT. Saanen goats had only enzyme activity of AST significantly higher (p < 0.05). Enzyme activity of alkaline phosphatase was significant higher (p < 0.05) in pluriparous goats in both breeds than in primiparous. The obtained results may represent a contribution to a better understanding of protein metabolism during puerperium in dairy and meat goats and for diagnostic purposes.     

LDH and CK isoenzyme patterns in the blood plasma of horses with elevated CK, LDH and AST activities

The distribution of LDH and CK isoenzymes in blood plasma of ten clinically sound Thoroughbreds with reasonable performance and without elevated clinico-chemical blood variables (reference group) was compared with 57 Thoroughbreds, which had histories of mild locomotor disturbances and/or poor performance and had elevated CK, LDH and/or AST activities (trial group). The trial group was subdivided according to the number of altered blood variables and in the groups with two as well as three altered blood variables also according to the extent of alteration of the total CK activity. The pattern of LDH and CK isoenzyme distribution in the blood plasma of the reference group was the following: 22% LDH1, 36% LDH2, 34% LDH3, 6% LDH4 and 2% LDH5 as well as 75% CK1 and 15% CK2. The remaining 10% of the plasma electropherogram could not be alloted to any one of the two CK bands. All trial groups built showed a similar pattern of changes in their isoenzyme distribution independent on kind and combination of altered enzyme activities. The shares of CK1, LDH4 and LDH5 were significantly increased whilst the shares of CK2, LDH1 and LDH2 decreased. A multiple analysis of variance demonstrated that only increased total CK activities had a pronounced effect on distribution of LDH and CK isoenzyme patterns in the trial group (p less than 0.01 for LDH2, LDH3, LDH4, CK1 and p less than 0.05 for CK2). The conclusion of the study was that the altered distribution pattern of LDH and CK isoenzymes of the trial group signalized an increased skeletal muscle membrane leakage.     

An improved microbiological assay for chlortetracycline in avian plasma

Bacillus cereus was used as the assay organism for the quantification of chlortetracycline (CTC) in avian plasma. Antibiotic medium #8 gave significantly larger zones of inhibition than nutrient agar 1.5% when used as the assay medium (P less than or equal to 0.05). When the CTC concentration was measured in serum, citrated plasma, heparinized plasma, and oxalated plasma, no significant differences were found between the inhibition zone diameters produced on antibiotic medium #8. However, there was a significant decrease in the zone diameters produced on this medium when citrated whole blood, oxalated whole blood, and heparinized whole blood were used instead of plasma. The length of incubation of assay plates was inversely related to the inhibition zone diameter, with an incubation time of 8 hr giving the largest and most distinct zones. Storing prepared assay plates at 4 C for 24 hr before use appeared to decrease the variability of the inhibition zone diameters. Storage of citrated plasma at 4 C for 48 hr and at -60 C for 9 days resulted in no significant decreases in CTC concentrations.     

Comparison of glucose concentrations in canine whole blood,plasma, and serum measured with a veterinary point-of-care glucometer

Previous studies have determined that, compared to whole blood, serum or plasma used in a portable blood glucometer (PBG) may provide more accurate results. We investigated the accuracy of a veterinary PBG (AlphaTRAK 2; Zoetis) for the measurement of glucose concentrations in serum, plasma, and whole blood compared to plasma glucose concentration measured by a biochemical analyzer. Blood samples from 53 client-owned dogs were collected. Lin concordance correlation coefficient (ρ_c) and Bland–Altman plots were used to determine correlation and agreement between the results obtained for the different sample types. Glucose concentration in whole blood measured by the veterinary PBG was more strongly correlated with the glucose concentration measured by the biochemical analyzer (ρ_c = 0.92) compared to plasma and serum glucose concentrations (ρ_c = 0.59 and 0.57, respectively). The mean differences between the glucose concentrations in whole blood, plasma, and serum measured by the veterinary PBG and the glucose concentration determined by the biochemical analyzer were 1.0, 6.3, and 6.7 mmol/L (18, 113, and 121 mg/dL), respectively. Our findings suggest that, when using this veterinary PBG, the accuracy of a glucose measurement obtained is higher when using whole blood compared to plasma or serum. Use of whole blood allows for more correct assessment and diagnosis, which are necessary for appropriate therapeutic intervention.     

Effect of storage on some constituents of camel serum

SUMMARY Effects of storage at room temperature (23–25°C) and refrigeration (4–5°C) on various biochemical constituents of camel serum were investigated. Albumin, globulin, calcium, phosphorus, cholesterol, aspartate aminotransferase (AST), alkaline phosphatase (AP) and gamma glutamyltransferase (GGT) did not change over 9 days when stored at 4–5°C. At 4–5°C, creatinine, iron and glucose in camel sera remained stable for 6 days; total protein for 7 days; and blood urea nitrogen for 8 days. Decreased activities in creatine kinase (CK), lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) were apparent after 1, 6 and 7 days, respectively. At room temperature, total protein, albumin, globulin, calcium and phosphorus were stable throughout the 9 days. Changes in glucose and iron occurred after 3 days. Stability at room temperature for LDH was 1 day; AST, 3 days; GGT and ALT, 6 days; and AP, 8 days. CK activity had already declined by 4 hours and by 9 days, only 34% activity remained.     

Stability of common biochemistry analytes in equine blood stored at room temperature

Reasons for performing study: Time delays between collection of blood samples and biochemical analysis of equine blood are unavoidably common in equine practice. The effect that delays may have on the accuracy of results of blood biochemical analyses is not well established. Hypothesis: Delays in processing of blood of up to 72h results in alterations in measured levels of common biochemical analytes that are of potential clinical relevance. Separation of serum prior to storage is protective against the effects of time delays. Methods: Samples of clotted blood, separated serum and oxalate fluoride plasma from 20 horses were stored and analysed at 0, 24, 48 and 72 h. Graphical exploration of each analyte was undertaken. General linear models with fixed effects were fitted for the whole blood data. The mean bias and 95% limits of agreement were calculated, using bootstrapped data, to assess agreement between pairs of samples analysed at 0 h and other time points. Bland‐Altman plots were used to explore general trends in the data. Paired t tests were used to compare the results from whole blood and separated serum. Results: Delays in processing equine blood resulted in significant increases in measured concentrations of aspartate aminotransferase, creatine kinase, lactate dehydrogenase, total bile acids and magnesium. A significant decrease in concentration was identified for glucose (serum and oxalate fluoride preserved plasma). Separation of serum immediately following clot formation resulted in nonsignificant increases in accuracy for some analytes. Conclusions and practical significance: Delays in processing of blood samples may result in biochemical changes of clinical relevance in individual cases; however, in the majority of cases, where delays are only a few days and a number of analytes are assessed concurrently, delays are unlikely to have an effect on the interpretation of results. Separation of serum following clot formation is of limited benefit. Clinical samples in which a delay in processing has occurred may be interpreted with reference to the data presented.     

Effects of heparin, citrate, and EDTA on plasma biochemistry of sheep: Comparison with serum

The effects of various types of anticoagulants on plasma biochemistry were studied in man and various animals, but limited information is existing for sheep plasma biochemistry. Ten clinically healthy Baloochi breed of sheep were blood sampled in different tubes containing each anticoagulants and plain tube for harvesting plasma and serum. The concentrations of glucose, cholesterol, total bilirubin, urea, creatinine, total protein, albumin, calcium, inorganic phosphorus, and magnesium and the activity of aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatine kinase (CK) and gamma glutamyl transferase (GGT) were measured. Except for the amounts of GGT, bilirubin and inorganic phosphorus, other measured parameters were significantly lower in citrated plasma than that of serum. For corrected citrated plasma significant differences were seen for the concentrations of glucose, creatinine, calcium and the activity of ALP.Most parameters did not show any difference, but significant increase was seen for albumin concentration when heparin was used as an anticoagulant. Using EDTA as anticoagulant caused a significant difference for the concentrations of some of the measured parameters in plasma except glucose, GGT, cholesterol, albumin, bilirubin, CK, and inorganic phosphorus comparing with serum.     

Stability of sorbitol dehydrogenase activity in bovine and equine sera

Serum sorbitol dehydrogenase (SDH) activities in 10 cows and nine horses were measured using an automated clinical analyzer. The serum samples were divided into aliquots that were stored at room temperature (21 degrees C), refrigerated (0-5 degrees C), or frozen (-30 degrees C). The stability of the SDH activity was monitored at various intervals. SDH activity in bovine sera remained stable for at least 5 hours at room temperature, 24 hours refrigerated, and 72 hours frozen without any significant (p < 0.05) differences from the initial serum values. In equine sera, SDH activity remained stable for at least 5 hours at room temperature and 48 hours frozen. The activity of the refrigerated equine sera was stable for at least 5 hours but less than 24 hours. An evaluation of fresh bovine serum and heparinized plasma samples indicated that there was no significant difference (p < 0.05) between the two sampling methods and that either may be employed for automated measurement of SDH activity following the established protocol. Sample type comparison indicated that there was a small but statistically significant (p < 0.05) difference between the results obtained comparing fresh serum and heparinized plasma samples for the horse. A reference range for Holstein cows was established using sera from 71 clinically healthy cattle (mean -/+ 2 SD = 32 -/+ 26 U/L).     

Application of the Vettest 8008 system for the biochemical analysis of vervet monkey plasma

A clinical biochemistry analyser designed specifically for veterinary use was used to analyse plasma samples from 24 vervet monkeys (Cercopithecus aethiops). Two millilitres of heparinised blood was collected from each of the 24 monkeys on four occasions at intervals of one week. Plasma was separated and analysed for the concentrations of triglycerides, cholesterol, total proteins, albumin, globulins, creatinine and blood urea nitrogen (BUN) and the activities of alkaline phosphatase (AP), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatine kinase (CK). The tests were easy to perform, used small volumes of plasma, and yielded consistent results for most of the analytes. The activities of CK and AP, but not AST, appeared to be influenced by haemolysis, and there were significant individual variations in the activity of LDH.     

Effects of storage times and temperatures on T3, T4, LH, prolactin, insulin, cortisol and progesterone concentrations in blood samples from cows

Little is known about stability of hormones in blood samples stored under various conditions. This study was conducted to examine stability of triiodothyronine (T3), thyroxine (T4), luteinizing hormone (LH), prolactin, insulin, cortisol and progesterone in blood and serum samples. Experiment 1 was designed to determine if concentrations of these hormones were affected by exposure to cellular elements of anticoagulated and coagulated blood when stored at 4 C and room temperature (22 to 26 C). Jugular venous blood was collected from six diestrous Holstein cows into evacuated bottles containing sodium ethylenediaminetetraacetic acid (EDTA), heparin or no anticoagulant. Subsamples of EDTA-treated and heparinized blood were stored .25, .5, 1, 2, 4, 8, 24 and 72 h at 4 C or room temperature. Subsamples of blood without anticoagulant were stored in polypropylene tubes (clot tubes) or serum separator tubes for 1, 2, 4, 8, 24 ad 72 h. Mean concentrations of T3, T4, LH, prolactin and cortisol did not change in plasma or serum from either of the four types of samples stored at 4 C or room temperature for 72 h. The mean insulin concentration decreased 18% by 72 h in serum from serum separator tubes stored at room temperature. At 4 C, mean progesterone concentrations decreased 55% by 24 h and 73% by 72 h in plasma from EDTA-treated blood; 41% by 72 h in serum from clot tubes, and 26% by 24 h and 36% by 72 h in serum from serum separator tubes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of limited concentrate feeding on growth and blood and serum variables, and on nutrient digestibility and gene expression of hepatic gluconeogenic enzymes in dairy calves

This study elucidated the effects of limited concentrate feeding on growth, nutrient digestibility, blood profile and gene expression of gluconeogenic enzymes in the liver of dairy calves. The study utilized 36 German Holstein dairy calves (5-7 days of age) divided into two groups of 18 calves each for 150 days. Control group calves received 2 kg/(calf × day) of concentrate, whereas calves in the restricted group received only 1 kg/(calf × day). Good quality forage (mixture of maize and grass silages) was available for ad libitum consumption to both groups. The intake of milk replacer before weaning, and of concentrate were recorded daily per calf; however, the consumption of forages was quantified as daily average of the group. Body weights (BW) were recorded at start and on days 35, 70, 112 and 150. Blood and serum samples and spot urinary and faecal samples were also collected at similar time points. On days 70 and 150, liver biopsies were collected from seven animals in each group. The BW was not different between the groups at all times. Total BW gain in the control group was 124 kg as opposed to 111 kg in restricted group that led to average BW gain of 827 g/day and 739 g/day in respective groups, and the differences were significant (p = 0.018). As planned, the control group had higher concentrate and lower forage intake than the restricted group. The blood haemoglobin, haematocrit and serum variables (glucose, total protein, albumin and urea) were within the normal range in both groups, but serum glucose was higher (p < 0.05) in control than in restricted group at 70 days. There was no difference between groups in organic matter (OM) digestibility which declined (p < 0.001) with increasing age in both groups. Microbial crude protein (MCP) synthesis estimated from urinary allantoin excretion increased (p < 0.001) in both groups with increasing age but was not different between groups. The mRNA expressions for the gluconeogenic enzymes, cytosolic and mitochondrial phosphoenol pyruvate carboxykinase (EC 4.1.1.32) and pyruvate carboxylase (EC 6.4.1.1) measured by quantitative real-time PCR in liver biopsies showed no differences between groups. Overall, restricting concentrate moderately reduced the growth intensity without affecting the normal serum and blood indices, and MCP synthesis and OM digestibility showed no differences between groups, indicating that both concentrate feeding schemes can be successfully applied.     

Stability of some serum enzymes in sheep, cattle, and swine during storage at different temperatures

Owing to the increased use of serum enzyme determinations in veterinary diagnostic work, greater knowledge about the keeping qualities of different animal sera under various storing conditions seems desirable.The present paper deals with the stability of serum aspartate aminotransferase (AspAT = GOT), alanine aminotransferase (A1AT = GPT), lactate dehydrogenase (LDH), and a-hydroxybutyrate dehydrogenase (HBD) in cattle, sheep, and swine.Sera from 14—16 animals of each species were analysed daily for 5 days after storage at room temperature (22°C) and in the refrigerator (4°C). Samples kept in the deep-freezer (—20°C) were reanalysed once after 32—38 days.Significant differences of serum activity were found between individuals for all enzymes in the three species.Great variations were found in the stability of enzyme activities of different species.To summarize, it may be said that the changes of transferase activities were less pronounced under the different storing conditions than those of the dehydrogenases investigated. Pig serum in particular showed heavy losses of the latter enzymes already after 1 day, more pronounced at refrigerator than at room temperature.As a consequence of the results obtained, practical recommendations for analytical work on these enzymes are suggested.     

Colloid osmotic pressure after hemorrhage and replenishment with Oxyglobin Solution, hetastarch, or whole blood in pregnant sheep

Objective To compare plasma colloid osmotic pressure (COP) of both maternal and fetal blood, before and after hemorrhage, and replenishment with Oxyglobin Solution (Biopure Corporation, Cambridge, MA, USA), hetastarch or whole blood in pregnant ewes. Study design Prospective, randomized study. Animals A total of 17 adult Rambouillet ewes at 131 (128–133) [median (minimum, maximum)] days gestation, weighing 56 (46, 63) kg. Methods Ewes and fetuses were chronically instrumented with catheters in a maternal jugular vein, maternal carotid artery and fetal femoral artery. Twenty milliliters per kilograms of blood were removed from each ewe over 1 hour. The ewes were then given 20 mL kg^?1 of either Oxyglobin Solution (n = 5), hetastarch (n = 6), or autologous whole blood (n = 6) IV. Maternal plasma COP was measured before hemorrhage, after hemorrhage, after replenishment, and 1 and 2 hours later. Fetal plasma COP was measured after maternal hemorrhage and 2 hours after maternal volume replenishment. Results Median COP of all ewes before hemorrhage was 20 (16, 24) mm Hg and after hemorrhage (p < 0.05), decreased to 16 (11, 19) mm Hg. After volume replenishment, the COP of the Oxyglobin Solution group was 22 (21, 25) mm Hg, the autologous whole blood group was 17 (16, 22) mm Hg and the hetastarch group was 20 (17, 21) mm Hg. The COP of the Oxyglobin Solution group was significantly greater (p < 0.05) than the COP of the hetastarch group immediately and 60 minutes after volume replenishment, and greater (p < 0.05) than that of the autologous whole blood group at 60 minutes after volume replenishment. The COP of all the fetuses after maternal hemorrhage was 16 (12, 19) mm Hg and at 120 minutes after maternal volume replenishment was 15 (11, 18) mm Hg. There were no differences in COP between or within any of the fetal groups. Conclusions When used to treat blood loss, Oxyglobin Solution increases plasma COP more than an equal volume of hetastarch in the first hour following administration. Maternal administration of Oxyglobin Solution did not alter fetal COP. Clinical relevance Oxyglobin Solution is a more potent colloid than hetastarch. Oxyglobin Solution did not appear to translocate fluid from the fetal to maternal circulation.     

Effects of blood processing techniques on sodium and potassium values: a comparison between Aldabra tortoises (Geochelone gigantea) and Burmese mountain tortoises (Manouria emys)

Background: Hematologic and plasma biochemical evaluations are routinely used in evaluating the chelonian patient, but appropriate processing techniques have been minimally defined.
Objectives: This study was designed to compare the effects of temperature, time, anticoagulant, and species on sodium and potassium values in the Aldabra tortoise ( Geochelone gigantea ) and the Burmese mountain tortoise ( Manouria emys ).
Methods: Blood samples from 7 Aldabra tortoises and 8 Burmese mountain tortoises were collected into tubes without anticoagulant and tubes containing lithium heparin. Sodium and potassium concentrations were measured by flame photometry in serum and plasma harvested immediately after collection and from aliquots of whole blood stored at 4°C and 25°C for 5 to 120 minutes.
Results: In Aldabra tortoises, storage time and temperature had no significant effect on potassium concentrations in heparinized blood and in blood without anticoagulant. However, sodium concentrations in serum and plasma decreased significantly in samples without anticoagulant stored at 4°C and 25°C and in heparinized samples stored at 4°C. In Burmese mountain tortoises, potassium concentrations in serum and plasma increased significantly with time in samples without anticoagulant and in heparinized samples stored at 4°C and 25°C, but the increases were less at 4°C. Sodium concentrations in serum and plasma decreased significantly in blood without anticoagulant and heparinized blood stored at 4°C and 25°C.
Conclusions: Storage of blood samples with and without anticoagulant at 4°C significantly improved the stability of potassium and sodium concentrations in both species of tortoises. Early separation of red cells from serum or plasma after blood collection is especially important to ensure the reliability of potassium measurements.     

血球蛋白粉和血粉的差异

本文主要从血球蛋白粉和血粉的感官、加工工艺、化学组成和新鲜度4个方面分析比较二者的差异,结果表明,血球蛋白粉的加工工艺比血粉更加科学、安全。其粗蛋白质和氨基酸含量显著高于血粉,比血粉更新鲜。     

A rapid microtechnique for in vitro stimulation of canine lymphocytes using whole blood

A simple, rapid microtechnique utilizing whole blood has been developed for evaluating the in vitro stimulation of canine lymphocytes. The test uses 5 ul. of heparinized whole blood per culture in a microtiter plate and requires no serum supplement. Cultures are harvested by an automated multiple sample cell harvester. This technique permits large numbers of replicate samples to be tested on individual animals with minimal amounts of blood and minimal technician time.     

Storage stability of some bovine plasma enzymes

Blood samples taken from domestic or wild ruminant animals typically require transportation to an analytical laboratory. Depending on circumstances, several hours or even a few days may pass between sampling and analysis. Several diagnostic plasma enzymes were measured in bovine blood samples immediately after sampling and after storage under a variety of conditions. Conditions studied included storing whole heparinized blood at 20 C for 6 hours, storage at 4 C for 3 and 5 days, and freezing freshly prepared plasma once and 4 times before analysis. For studies of erythrocyte enzymes, fresh erythrocytes were compared with erythrocytes frozen once, frozen 4 times, and prepared from whole blood stored for one week at 4 C. None of these conditions deteriorated erythrocyte acetylcholinesterase. The serum pseudoacetylcholinesterase and lactate dehydrogenase were not affected by any storage condition used. By contrast, acid phosphatase was significantly decreased by all storage conditions used. Ornithine carbamoyltransferase, alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase were stable under some of the storage conditions tested.