Plasma Chloride Concentrations Research Articles

Anesthesia of horses with a combination of detomidine, zolazepam, tiletamine, and isoflurane immediately after strenuous treadmill exercise

Abstract Objectives To evaluate effects of strenuous exercise in adult horses immediately before anesthesia and to determine whether prior exercise affects anesthesia induction, recovery, or both. Animals 6 healthy Thoroughbreds in good condition and trained to run on a treadmill, each horse serving as its own control. Procedure Horses ran on a treadmill until fatigued, then were sedated immediately with detomidine hydrochloride and anesthetized with a zolazepam hydrochloride-tiletamine combination. Anesthesia was maintained with isoflurane in oxygen for another 90 minutes. Blood samples were taken before, during, and after exercise and during anesthesia. Results During exercise, changes in heart rate, core body temperature, plasma lactate concentration, arterial pH, and PaCO2 were significant. Plasma ionized calcium concentration was lower after exercise, compared with baseline values, and remained lower at 30 minutes of isoflurane anesthesia. Compared with baseline values, plasma chloride concentration decreased significantly during anesthesia after exercise. Cardiac output during anesthesia was significantly lower than that during preexercise, but significant differences between experimental and control periods were not observed. Arterial blood pressure during anesthesia was significantly lower than that during preexercise and initially was maintained better during isoflurane anesthesia after exercise. Cardiac output and blood pressure values were clinically acceptable throughout anesthesia. Conclusion Administration of detomidine hydrochloride followed by zolazepam hydrochloride-tiletamine appeared to be safe and effective for sedation and anesthesia of horses that had just completed strenuous exercise. Clinical Relevance Anesthetic given in accordance with this protocol can be used to anesthetize horses that are injured during athletic competition to assess injuries, facilitate first aid, and possibly allow salvage of injured horses. (Am J Vet Res 1999;60:743–748)

Increase of heart rate without elevation of cardiac output in adult Atlantic salmon (Salmo salar) exposed to acidic water and aluminium

Adult Atlantic salmon (Salmo salar) were exposed for 48 h to water from acidified (pH 5.2) Fossbekk River (Norway), with and without 94 µg aluminium (Al)/L added as AlCl3, and to water from circumneutral (pH 6.7) Ims River (Norway) (controls). Cardiac output, heart rate, and stroke volume were monitored throughout the exposure period with Doppler flow probes placed around the ventral aorta of the fish. Fish exposed to Fossbekk River water without added Al showed few physiological disturbances. When 94 µg Al/L was added to Fossbekk River water, most of the fish died before the end of the 48-h exposure period, and a large elevation in heart rate was observed together with a decrease in plasma chloride concentrations and an increase in haematocrit, plasma glucose and plasma cortisol levels. Cardiac output was maintained at basal levels during the first 24 h of exposure because the tachycardia was accompanied by a concomitant reduction of stroke volume. Signs of arrhythmia appeared after 32 h of exposure and were associated with a further decrease in stroke volume that caused cardiac output to decrease below basal levels. The incapacity of the tachycardia to elevate cardiac output and the subsequent death of the fish suggest that this response to low pH and Al is more of a maladaptation reaction than a compensatory or adaptative reaction.

Atlantic salmon smolts are more responsive to an acute handling and confinement stress than parr

Atlantic salmon parr and smolts reared under a natural temperature and photoperiod regime were subjected to an acute handling and confinement stress in early May. Smolts had a mean plasma cortisol concentration of 10 ng/ml before stress and 242 ng/ml 3 h after initiation of stress which returned to pre-stress levels within 8 h. Parr had a plasma cortisol concentration of 4 ng/ml prior to stress which increased to 11 ng/ml 3 h after initiation of stress and returned to pre-stress levels within 8 h. Plasma glucose was significantly higher in parr and smolts 3 h after initiation of stress; in parr, plasma glucose returned to pre-stress levels within 8 h, but not until 48 h in smolts. Plasma chloride concentration in smolts decreased from 139 to 124 mM 3 h after initiation of stress but returned to pre-stress levels within 24 h; plasma chloride in parr was not altered by stress. Plasma thyroxine of parr and smolts peaked at 3 h after initiation of stress and returned to pre-stress levels within 8 h, but smolts had 72% higher levels at 3 h. Pre-smolts (February) and smolts (May) reared under constant temperature (8–10°C) were also subjected to a handling and confinement stress. Although peak levels of plasma cortisol 3 h after initiation of stress were twice as high in smolts, other physiological and endocrine responses were not substantially different between pre-smolts and smolts. The results demonstrate that Atlantic salmon smolts are more responsive to stress than parr and that developmental differences are more important than seasonal changes.

Alterations in acid-base balance and serum electrolyte concentrations in cattle: 632 cases (1984–1994)

Objective To determine typical alterations in acid-base balance and serum electrolyte concentrations in cattle grouped on the basis of age, breed type, hydration status, clinical signs, and underlying disease. Design Retrospective study. Animals 632 cattle. Procedure Information on blood pH, Pvo2, Pvco2, HCO3− concentration, and base excess (BE) as well as serum or plasma sodium, potassium, chloride, and total carbon dioxide concentrations was obtained. Values for calves (ie, cattle ≥ 1 month old) were compared with values for cattle ≥ 1 month old. Within each age-group, values were compared for cattle grouped on the basis of breed type, previous treatment, and hydration status. Proportions of cattle with various disorders for which values were within, greater than, or less than reference ranges were determined. Results BE, pH, and HCO3− concentration were significantly higher and Pvco2 and sodium, potassium, and chloride concentrations were significantly lower among cattle ≥ 1 month old than calves. Base excess and HCO3- concentration were significantly lower among dairy than beef calves. Sodium and potassium concentrations were significantly lower among dairy than beef cattle ≥ 1 month old. A higher proportion of cattle that did not survive had a high anion gap than cattle that did survive. Sodium, potassium, and chloride concentrations were significantly lower among dehydrated cattle than cattle that were not dehydrated. Clinical Implications Because certain alterations were consistently found in some groups of cattle, it may be possible to make reasonable predictions of alterations in acid-base balance and serum electrolyte concentrations when laboratory evaluations are not available. (J Am Vet Med Assoc 1998;212:1769–1775)

Plasma pharmacokinetics of intravenous and intramuscular furosemide in the camel ( Camelus dromedarius)

Single bolus intravenous (i.v.) and intramuscular (i.m.) doses of furosemide (1·5 mg kg −1) were administered in a crossover design to three female and three male adult, dromedary camels. Plasma furosemide concentrations were assayed by HPLC and sodium, potassium and chloride concentrations were measured using ion-selective electrodes. Plasma furosemide concentration-time plots indicated multi-compartment disposition, and there was considerable intersubject variability in the pharmacokinetic parameters. The mean (SD) i.v. terminal elimination half-life was 118 (67) minutes. The systemic clearance was 5·4 (1·2) ml min −1 kg −1, and the steady-state volume of distribution was 0·43 (0·14) litre kg −1. The mean absorption time after i.m. dosing was 33 (62) minutes, while the absolute bioavailability was 71 (20) per cent. The glucuronide metabolite of furosemide was not detected in plasma. Clearance was lower, volume of distribution was larger, and half-life was longer compared with published data for dogs, horses, rats and humans. Plasma potassium and sodium concentrations were significantly diminished (P<0·05) by an average of 35·6 per cent (two to six hours post-dose) and 11·3 per cent (eight hours post-dose), respectively. Plasma chloride concentrations were not significantly affected by furosemide administration.

Sublethal effects and safe levels of carbon dioxide in seawater for Atlantic salmon postsmolts ( Salmo salar L.): ion regulation and growth

Atlantic salmon ( Salmo salar L.) postsmolts (0.17–0.26 kg) were exposed to four different levels of carbon dioxide partial pressure for 43 days in an open flow system: 0.6 mm Hg (control), 4.9 mm Hg (low), 12 mm Hg (medium), and 20 mm Hg (high). The water temperature was 15–16°C and the salinity 34‰. In the low carbon dioxide group ( P CO 2 =4.9 mm Hg; 10.6 mg/l), no significant differences were found in blood parameters (haematocrit, plasma chloride and plasma sodium) or in growth parameters (weight, length and condition factor) when compared to the control group. After 43 days, the mean plasma chloride concentration for the medium group ( P CO 2 =12 mm Hg; 26 mg/l) was significantly reduced, while weight and condition factor were slightly, although not significantly, lowered. For the high carbon dioxide group ( P CO 2 =20 mm Hg; 44 mg/l) plasma sodium and plasma pH were significantly increased and plasma chloride, oxygen consumption, weight, length and condition factor were significantly reduced at the end of exposure. There was no mortality in the control group or in the low carbon dioxide group. The mortalities in the medium and high carbon dioxide groups were 1.1 and 4.3%, respectively. Nephrocalsinosis was not observed in any of the groups. The results of the present investigation indicate that the CO 2 concentration of the low group may represent a safe level for Atlantic salmon postsmolts when the temperature is 15–16°C and the oxygen level is 6–7 mg/l. Further studies are required.

The effect of dietary lipid on polyunsaturated fatty acid metabolism in Atlantic salmon (Salmo salar) undergoing parr-smolt transformation.

The aim of this study was to measure the changes in lipid metabolism which occur during smoltification and seawater transfer in Atlantic salmon (Salmo salar). Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO) or a blend of linseed and rapeseed oils, vegetable oil (VO), from October (week 0) to seawater transfer in May (week 26). From May to August (weeks 26-43), all fish were fed a fish oil-containing diet. Fatty acyl desaturation and elongation activity were followed in isolated hepatocytes incubated with radioactive 18:3n-3 and 18:2n-6. Metabolism of 18:3n-3 was consistently around 5-fold greater than metabolism of 18:2n-6, and total metabolism of both substrate polyunsaturated fatty acids (PUFA) was increased in fish fed both VO and FO up to seawater transfer after which desaturation activities were reduced. Desaturation activities with both 18:3n-3 and 18:2n-6 were significantly greater in fish fed VO, compared to fish fed FO, at 22 and 26 wk. Arachidonic acid (20:4n-6; AA) in liver polar lipids (PL) of fish fed VO increased consistently from weeks 0-22 but varied after seawater transfer. In fish fed FO, AA in liver PL remained constant up to week 17 before increasing at seawater transfer and leveling off thereafter. Eicosapentaenoic acid (20:5n-3; EPA) in liver PL of fish fed VO decreased significantly from week 0-22 before rising at seawater transfer and increasing rapidly posttransfer. EPA in liver PL of fish fed FO showed a similar trend except EPA was always greater in the freshwater phase compared to fish fed VO. Docosahexaenoic acid (DHA) levels in liver PL of fish fed VO remained constant in the seawater phase before increasing following seawater transfer. In fish fed FO, DHA in liver PL increased from weeks 0-17 reducing and leveling off postseawater transfer. The levels of PGF(2 alpha) and PGF(3 alpha) were measured in isolated gill cells stimulated with calcium ionophore A23187. PGF(2 alpha) production in fish fed VO increased significantly between 0-7 wk before decreasing toward seawater transfer. After transfer, PGF(2 alpha), production increased to a peak at 35 wk. PGF(2 alpha) production in fish fed FO was not significantly altered during the trial period. The changes in PGF(3 alpha) production were broadly similar to those occurring with PGF(2 alpha), but the latter was always in excess of the former (2- to 4-fold). Plasma chloride concentrations in fish subjected to seawater challenge at 20 wk were significantly lower in fish fed VO compared to those fed FO. This study has provided new information on the changes in lipid metabolism which accompany parr-smolt transformation and suggests that diets which have a fatty acid composition more similar to that in aquatic invertebrates may be beneficial in effecting successful seawater adaptation.

Hyperosmotic-hyperoncotic solutions during abdominal aortic aneurysm (AAA) resection.

A largely positive perioperative fluid balance during both elective and emergency abdominal aortic aneurysm repair (AAA) may put patients at risk of developing left ventricular failure and may thus contribute to morbidity. In the present paper we report on a prospective study using hyperosmotic-hyperonocotic solutions (HHS) infused during clamping of the aorta, for the prevention of declamping shock, and the associated reduction in perioperative fluid requirements. The major aim of this paper was to determine the efficacy of an HHS infusion when given over 20 minutes and to detect possible adverse effects of HHS. For perioperative fluid replacement 12 patients received crystalloid solutions with HHS [250 ml of 7.2% NaCl combined with either 6% Dextran (n = 3), 6% Hydroxyethylstarch (HES, n = 4) or 10% HES (n = 5)]. In 16 controls, crystalloids with 1000 ml of HES 10% were infused. Patients were invasively monitored and hemodynamic parameters frequently assessed during the operation, which were statistically analyzed in relation to the start of the fluid loading during clamping of the aorta. One patient showed an anaphylactoid reaction to HES, otherwise no side effects of HHS were observed during infusion (no hypotension, no pathological EKG changes). Plasma sodium and chloride concentration as well as osmolality rose resulting in an osmotic gradient and a desired intravascular volume expansion. Prior to declamping pulmonary capillary wedge pressure had increased to the desired value of > 13 mmHg and < 18 mmHg. Oxygen delivery was significantly elevated upon HHS and remained so post declamping, whereas no change was observed in controls. During clamping systemic vascular resistance was significantly decreased, but was unchanged in controls. The perioperative fluid balance of patients receiving HHS was 2471.0 +/- 948.6 ml, which was significantly less than + 3386.7 +/- 1247.9 ml of controls (P < 0.01). We suggest that HHS opens new perspectives in perioperative fluid management of both elective and emergency AAA repair, since hemodynamic parameters are improved and the overall fluid balance is less positive, thus decreasing the likelihood of edema formation. Moreover, the previously described positive microcirculatory effects of HHS may be particular beneficial in some high-risk patients.

Stress responses of Atlantic salmon (Salmo salar L.) elicited by water level reduction in rearing tanks

The Atlantic salmon (Salmo salar) stress response was examined by measuring plasma cortisol, glucose and chloride in fish after water level reduction within rearing tanks. Maximum plasma cortisol levels (366±43 (SD) nM and 534±280 nM for Groups 1 and 2, respectively) were observed 20 min after application of the stressor. Cortisol levels were down to control levels 24 h later. The pattern for cortisol changes observed within these two groups were comparable. Plasma glucose and chloride concentrations did not change significantly in either of the experimental groups. The fish in group 2 were then repeatedly subjected to the same stressor every third day. After the fifth exposure to the stressor, blood was obtained from fish at times corresponding to sampling after the first exposure. Their maximum plasma cortisol level only reached 223 (±96) nM, and was down to prestress levels within 2 h. Plasma glucose and chloride concentrations did not change significantly in this second experiment. This challenge test revealed an acute primary response in Atlantic salmon without any apparent harmful secondary responses, that may thus serve as a standardized reference stressor using other fish groups under comparable conditions.

Smolt characteristics of small first-time migrant, and resident Arctic charr, Salvelinus alpinus (L.), from a river system in northern Norway

Smolt characteristics were investigated in sympatric anadromous and resident Arctic charr. Salvelinus alpinus (L.), of a similar size (11-20 cm), A group of first-time migrant anadromous charr was caught while descending the Hals River and two groups of resident conspecifics were caught in Lake Storvatn. one before, and one after, the sea-run of anadromous fish had terminated. When sampled immediately after capture in fresh water the anadromous group had a higher proportion of fish visually classified as smolts. and these charr had higher gill Na+-K+ ATPase activity, higher densities of developed chloride cells in the gills, a lower condition factor, and lower plasma osmolality, than resident fish. When exposed to sea water (33%o S), only minor differences in mortality and plasma electrolyte levels were observed between anadromous and resident fish, average values of plasma osmolality and chloride concentrations being 377 mOsm and 169 mM and 387 mOsm and 174 mM, respectively. The results suggest that the first-time migrant Arctic charr had undergone some of the physiological changes that are considered typical for a parr-smolt transformation before they left fresh water. Such changes did not appear to have occurred in sympatric, resident, fish of a similar size. The parr-smolt transformation in the first-time migrants may, however, have been incomplete, because the fish did not appear to have the ability to rapidly re-establish osmo- and ionoregutatory homeostasis after direct transfer to sea water.

Fetal electrolyte and acid-base responses to amnioinfusion: lactated Ringer's versus normal saline in the ovine fetus.

We hypothesized that amnioinfusion with normal saline would increase fetal plasma sodium and chloride concentrations, resulting in a hyperchloremic acidosis, and that these alterations would not occur after amnioinfusion with lactated Ringer's solution. Chronically catheterized fetal sheep (137 +/- 1 days' gestation; mean +/- SE) were divided into three groups: control (n = 8), infused with normal saline (n = 10), and infused with lactated Ringer's solution (n = 10). The protocol consisted of a 30-minute pre-infusion period, a 1-hour amnioinfusion, and a 1-hour recovery period. During amnioinfusion, warmed solution was infused at a rate of 100 mL/minute for 1 hour. Fetal plasma and amniotic fluid electrolyte concentrations and osmolalities were measured every 20 minutes. Statistical analysis was by analysis of variance and linear regression. Amniotic fluid electrolyte concentrations changed significantly (P < .001) in both amnioinfusion groups, resulting in amniotic fluid compositions that were essentially the same as the infused fluid 20 minutes after starting the amnioinfusion. Significant increases in fetal plasma Na+ and CI- concentrations (2-3 mEq/L) occurred in the normal-saline infusion group relative to both the control and lactated Ringer's groups (P < .001). The lactated Ringer's group demonstrated only a modest increase in plasma Na+ (P = .04) and no change in plasma Cl- concentration. Fetal arterial pH decreased (-0.015 U) in the normal-saline group, and the change in fetal pH was linearly related to the change in plasma Cl- concentration (r = -0.532, P = .004). Normal-saline amnioinfusion can significantly alter fetal plasma electrolyte concentrations and blood pH, whereas amnioinfusion with lactated Ringer's solution results in minimal changes in fetal electrolytes and acid-base balance. The fetal plasma changes that occur during saline infusion are in the physiologic but not the pathologic range.

Effect of copper on the haematology and osmoregulation of the Mozambique tilapia, Oreochromis mossambicus (Cichlidae)

The haematology of Oreochromis mossambicus was investigated after short-term (96 hr) exposures to 0.16 mg/l and 0.40 mg/l, respectively, as well as long-term (4 wk) exposure of 0.40 mg/l copper, at two temperatures. After the exposure of two sublethal copper concentrations a physiological effect was exerted on O. mossambicus, at both temperatures, by causing changes in the blood biochemistry such as leucocytosis and erythrocytopenia. Morphological changes in the gills, as reflected by the decreases in the plasma sodium, potassium, calcium and chloride concentrations, although not lethal, had a significant effect on the respiration and osmoregulatory function of the gills. Those morphological changes can be regarded as primary changes, which will inevitably lead to secondary physiological changes as well as responses that could affect various organ systems. Changes can be seen as an initial response to copper (the toxicant) or as an adaptation reaction to retain a normal condition.

The biology of purified stem cells

1.1. Decreased survival occured for juvenile coho salmon following doses of X-radiation ⩾ 1000 r when transferred from hypo-osmotic to a hyperosmotic environment (0%–30% salinity).2.2. Survivors which had remained in salt and fresh water 60 days post-irradiation were sacrificed for plasma sodium, chloride and osmotic concentrations. Increased levels (P <0·005, >0·01) were noted between the control (0 r) and the irradiated (⩾1200 r) group of saltwater fish; while no significant elevations occured between irradiated and non-irradiated fish remaining in fresh water.3.3. Sites of histopathological changes in saltwater fish were found principally in the extrarenal system (gills, caecae and intestine) with severe damage noted in the gill lamellae. No damage was apparent in the kidney.4.4. No histopathological changes were noted in fish receiving the same anount of irradiation but which remained in fresh water.

HIV infection in children

1.1. Decreased survival occured for juvenile coho salmon following doses of X-radiation ⩾ 1000 r when transferred from hypo-osmotic to a hyperosmotic environment (0%–30% salinity).2.2. Survivors which had remained in salt and fresh water 60 days post-irradiation were sacrificed for plasma sodium, chloride and osmotic concentrations. Increased levels (P <0·005, >0·01) were noted between the control (0 r) and the irradiated (⩾1200 r) group of saltwater fish; while no significant elevations occured between irradiated and non-irradiated fish remaining in fresh water.3.3. Sites of histopathological changes in saltwater fish were found principally in the extrarenal system (gills, caecae and intestine) with severe damage noted in the gill lamellae. No damage was apparent in the kidney.4.4. No histopathological changes were noted in fish receiving the same anount of irradiation but which remained in fresh water.

Cardiovascular responses to acute handling stress in the Antarctic fish Trematomus bernacchii are not mediated by circulatory catecholamines

Cannulated specimens of the benthic Antarctic teleost Trematomus bernacchii were subjected to a five min period of handling stress, following which blood pressures were measured and then blood samples taken for measurement of plasma catecholamine concentrations. There were two control groups of fish, one group of undisturbed fish at Scott Base, Antarctica and the other group of undisturbed fish measured in Christchurch.Plasma catecholamine concentrations were not changed following 5 min of acute handling stress. However, heart rate, ventral aortic blood pressure and haematocrit were elevated following handling, suggesting increased sumpathetic nerve activity. The low plasma catecholamine concentrations measured in all three groups of fish are similar to those found in other species of teleost at rest.The resting heart rates found in this series of experiments were approximately double those recorded in previous work on this species and this difference may be correlated with the length of time that the fish are held in captivity. The fish transported to Christchurch also had higher mean cell haemoglobin concentrations (MCHC) and lower plasma chloride concentrations.

Interrelationships between fluid, electrolyte and acid‐base balance during maximal exercise

SummaryExercise at maximal intensity results in marked, but transient alterations in plasma electrolyte concentration and acid‐base balance. Compartmental fluid shifts contribute to the increased haematocrit, plasma protein and electrolyte concentrations. Elevations in plasma sodium and potassium concentrations relative to chloride tend to ameliorate the impact of lactate accumulation on anion‐cation balance. Lactate accumulation is associated with the development of a profound metabolic acidosis, but there are physiologically important differences between the mixed venous and arterial acid‐base values. Arterial blood is characterised by a moderate hypoxaemia, marked acidosis, modest increase in the partial pressure of carbon dioxide (PCO2) and a marked decrease in bicarbonate. Mixed venous blood pH is lower than arterial and is associated with a profound increase in PCO2 with a slight increase in bicarbonate. It is estimated that over 70% of the CO2 produced during maximal exercise is transported as bicarbonate in the venous circulation. This is largely a function of the carbonic anhydrase‐dependent chloride shift in which erythrocytes participate in CO2 transport from the tissues to the lungs. The chloride shift is responsible for the mixed venous‐arterial differences in plasma chloride concentration. The compartmental fluid shifts as well as the alterations in plasma electrolyte concentration and acid‐base balance are part of the integrated physiological response to the energy generating metabolic events associated with maximal exercise.

Effect of diet on weight and plasma variables in endurance exercised horses

SummaryThe purpose of this study was to determine whether a difference in roughage intake could affect electrolyte and water balance in horses during endurance type exercise. In each of 2 experiments, 2 treatments (a high hay or limited hay diet) were assigned in a crossover design so that each horse performed 2 exercise tests, 1 on each treatment. In experiment 1, diet was controlled only the night before the exercise test. Water intake was lower (P&lt;0.001) when horses received the limited hay diet. Exercise caused a decrease in plasma chloride and potassium concentration and an increase in plasma total protein concentration, but there were no diet differences (P&gt;0.05). Weight loss was 2.8% of body weight for both treatments. In experiment 2, horses were adapted to the diets for 7 days prior to the exercise test. Again, water intake was lower when the horses received the limited hay diet (P&lt;0.01). During exercise, both groups lost about 4% of bodyweight, but total protein concentration was lower (P&lt;0.05) in the horses receiving the high hay diet. Plasma potassium concentration initially increased and then decreased during exercise (P&lt;0.05), but the horses receiving the high hay diet maintained a higher potassium concentration during exercise (P&lt;0.05). Sodium was not affected by diet or exercise (P&gt;0.05). Plasma chloride concentration decreased during exercise (P&lt;0.05). The increased water intake and lower plasma protein concentration associated with the hay diet may be beneficial for horses involved in endurance type exercise.

Adrenocortical function in neonatal and weanling Beagle pups

Abstract Adrenocortical function was assessed in 27 Beagle pups at 2, 4, 6, 8, 10, and 12 weeks of age by determination of plasma sodium, potassium, and chloride concentrations; serum aldosterone and cortisol concentrations; and plasma ACTH concentrations. Serum cortisol concentration was measured before and 1 and 2 hours after IM administration of 2.2 IU of acth/kg of body weight. Serum progesterone concentration also was determined for all pups at 2, 4, and 6 weeks of age. Mean baseline cortisol concentration was lower for pups 8 weeks old or younger than for mature dogs. Nevertheless, mean serum ACIH-stimulated cortisol concentration in dogs of all age groups increased into the adult reference range after administration of acth. For pups 4 weeks old or younger, increase in cortisol concentration was maximal at 2 hours after acth administration. However, in pups between 6 and 12 weeks of age, the increase in cortisol concentration was maximal 1 hour after acth administration in about a third of the pups, whereas the remaining pups had peak values at 2 hours. Mean plasma sodium, potassium, and chloride concentrations for each age group were within the reference ranges established for mature dogs, with the exception of lower mean plasma sodium and chloride concentrations in pups 4 weeks old or younger. Mean serum aldosterone concentration in pups of each age group was substantially higher than the range of aldosterone concentrations for clinically normal mature dogs. Median progesterone concentration was uniformly less than 0.2 ng/ml for all pups 6 weeks old or younger. The normal endogenous acth concentration and adequate cortisol responses to exogenous acth seen in our pups would support functional pituitary gland and adrenal cortex for cortisol production. The low baseline cortisol concentration observed in the pups of this study may be related to reduced binding of cortisol to plasma proteins, as exists in human infants. The hyponatremia and increased aldosterone concentration may be explained by reduced renal tubular response to aldosterone, as also evidenced in the human infant kidney.

The effect of water deprivation and subsequent access to water on plasma electrolytes, haematocrit and behaviour in red deer

Abstract To determine the water needs of farmed deer during transport and handling, red deer hinds were observed before and after a period of water and feed withdrawal of 2 or 20 h and during a subsequent 6-h period of confinement when water was available. Behaviour related to drinking was recorded during the test period. Haematocrit and plasma electrolytes (sodium, chloride and potassium) were measured in blood samples taken throughout the study. Plasma sodium and chloride concentrations were significantly elevated after 20 h without water (P

Diuretic Effects of Irrigating Fluids Containing Mannitol and Sorbitol

We studied urine excretion and plasma electrolytes in 38 rabbits during and after a 60-min intravenous infusion of 150 ml/kg of irrigating fluid containing either 3.3-6% of mannitol, 5% sorbitol, or 2.7% sorbitol and 0.54% mannitol (Cytal). The Osmolality of the solutions ranged between 165 and 350 mosmol/kg. The excreted urine volume, peak flow rate, duration of 80% of peak urine flow and the ratio of urine excreted per volume of infused irrigating fluid varied greatly but in direct proportion to the osmolality of each solution. There were no differences between the irrigating fluids with respect to dilution changes in plasma sodium and chloride concentrations. We conclude that the urine flow after infusion of irrigating fluids is governed primarily by the osmolality of the solution. Mannitol has no superior effect over sorbitol as a diuretic.