Adaptive responses of calcium and phosphate homeostasis in goats to low nitrogen intake: renal aspects

In a previous study, in goats, we showed that apart from variations in dietary calcium (Ca) and phosphorus intake, also low dietary nitrogen (N) intake altered plasma concentrations of hormones, which regulate Ca and phosphate (P_i) homeostasis. These hormonal responses in goats were in accordance with findings in monogastric animals and humans with low protein intake. In the aforementioned studies, alterations of electrolyte transport in the kidneys were also observed. However, whether renal electrolyte transport in goats is also involved in the adaptation of Ca and P_i homeostasis to low N intake remains unknown. Thus, the aim of the present study was to investigate whether in addition to the hormonal changes, as observed in our former study, renal Ca transport and renal P_i transport were also altered by low N intake in goats. Therefore, in kidney samples from the goats used in our former study, the protein expression of Ca and P_i transporters and of related regulatory proteins was examined. Furthermore, the uptake of P_i into isolated brush border membrane vesicles (BBMV) was detected. The results showed that the protein amount of the renal sodium‐dependent P_i transporter NaPi IIa was elevated, and concomitantly, protein expression of its upstream regulators, the parathyroid hormone receptor and the extracellular signal‐regulated kinases 1 and 2 was decreased. However, P_i uptake into renal BBMV was not enhanced. Furthermore, protein expression of the renal Ca channel, the transient receptor potential cation channel subfamily V member 5 (TRPV5) and of the vitamin D receptor was not influenced by dietary N reduction. We conclude that regulation of renal P_i transporter expression in goats is involved in the adaptation of electrolyte homeostasis to low N intake.     

饲粮电解质平衡对动物营养物质代谢的影响

饲粮电解质平衡状况可影响动物机体酸碱平衡,进而影响营养物质的消化吸收率,还可通过改变一些酶的活性而影响氨基酸等养分的代谢利用。     

Abnormalities of Serum Magnesium in Critically III Dogs: Incidence and Implications

Serum magnesium (Mg) is an infrequnetly measured electrolyte in small animal patients. Currently, little is known about the prevalence and significance of abnormalities in serum Mg in animals. Therefore, a prospective study was performed to examine the incidence and clinical implications of abnormalities in serum Mg levels in critically ill dogs.
Serum Mg and other electrolytes were measured in 93 normal dogs housed at the Purina Pet Care Center and in 48 ill dogs admitted to a small animal critical care unit. The normal reference range for canine serum Mg was determined to be 1.89 – 2.51 mg/dl. Based on this range, 54% of the critically ill dogs were hypomagnesemic (< 1.89 mg/dl) and 13% were hypermagnesemic (> 2.51 mg/dl). Of the electrolytes measured in these patients, serum Mg had the highest prevalence of abnormal values. Hypomagnesemic patients had a significantly higher incidence of concurrent hypokalemia and hyponatremia (p < 0.05), as well as a longer length of hospitalization (p < 0.05) than their normomagnesemic counterparts. Hypermagnesemic patients were 2.6 times more likely not to survive their illness when compared to patients with normal serum Mg levels.
Abnormalities in serum Mg appear to be common in critically ill dogs. These patients commonly have other concurrent electrolyte abnormalities. Since serum Mg is not routinely measured, the presence of hypokalemia or hyponatremia should alert the clinician to the possibility of coexisting hypomagnesemia. The clinical implications of hypomagnesemia and hypermagnesemia in ill dogs appear to involve prolonged hospitalization and increased mortality, respectively: however, the exact etiology remains undetermined.     

Blood acid-base and plasma electrolyte values in healthy ostriches: The effect of age and sex

The effect of age and sex on blood acid-base and plasma electrolyte values was determined in venous blood samples from 45 clinically healthy ostriches (Struthio camelus) from 26 days to 6 years of age. Animals were divided by age into four groups and the group of adults was divided by sex into two subgroups. Blood samples were collected without sedation. There was a significant (P < 0.05) age difference in blood values of base excess (BE), plasma , total CO₂ (TCO₂), Na⁺, K⁺, Cl⁻ and anion gap (AG). The highest plasma concentrations of Na⁺, Cl⁻ and value of AG were found in adult ostriches with a steady decrease to chicks. A significant (P < 0.05) sex difference in adult animals with higher blood pH, lower blood values of pCO₂, BE, plasma concentrations of , TCO₂ and K⁺ was found in females. We concluded that blood acid-base values and plasma electrolyte concentrations in ostriches are affected by age and sex.     

Peritoneal dialysis in the management of acute renal failure in 5 dogs with leptospirosis

Objective: To describe the use of peritoneal dialysis (PD) in the management of 5 dogs with acute renal failure (ARF) caused by leptospirosis. Case Series Summary: All dogs were treated for leptospirosis with intravenous (IV) fluids and ampicillin prior to PD. Median age of dogs was 5 years (range 2–6 years). All dogs had positive titers for Leptospira bratislava. Median duration of PD was 4 days (range 3–16 days). PD resulted in a decrease in azotemia in all dogs. Median serum blood urea nitrogen at the start of PD was 192 mg/dL (range 140–235 mg/dL) and at the end of PD was 63 mg/dL (range 48–139 mg/dL). Median serum creatinine at the start of PD and the end was 12.8 mg/dL (range 7.7–16.9 mg/dL) and 3.4 mg/dL (range 1.4–11.1 mg/dL), respectively. Complications identified during PD included hypokalemia (n=3, 60%), hypoalbuminemia (n=2, 40%), hypomagnesemia (n=1, 20%), pelvic limb edema (n=2, 40%), central nervous system signs (n=2, 40%), dialysate retention (n=1, 20%), and leakage from the catheter site (n=1, 20%). Peritonitis was not identified in any of the dogs. Four dogs (80%) survived to discharge from the hospital. PD was effective for management of uremia in dogs with ARF caused by leptospirosis.     

高温对草坪草细胞的伤害

环境温度超过植物最大效应能力时伤害生物膜,使胞内电解质透出率增多,则成不可逆反应,引起细胞死亡。我们所测试草种的半致死温度出现在48～60℃的范围内。     

松针褐斑病毒素诱发紫茎泽兰电解质渗漏对几种真菌的影响

松针褐斑病菌毒素是一种非寄主专化性毒素,能够伤害紫茎泽兰叶片,引起细胞电解质渗漏。电导率测定结果表明,毒素粗提液对紫茎泽兰的伤害活性最强,LA-I次之,LA-II最弱。孢子萌发试验和菌丝生长试验显示,紫茎泽兰电解质对青霉菌、木霉菌、尖孢镰刀菌、链格孢菌的孢子萌发和菌丝生长都有不同程度的抑制作用,但是对泽兰尾孢菌的孢子萌发和菌丝生长有促进作用。毒素粗提液对供试真菌的的孢子萌发和菌丝生长没有明显的抑制作用和促进作用。分析认为将松针褐斑病菌毒素与泽兰尾孢菌混和将可能提高对紫茎泽兰的除草效果。     

松针褐斑病菌毒素诱发紫茎泽兰矿质元素渗漏的研究

采用电感耦合等离子体发射光谱法（ICP-OES）测定了松针褐斑病菌毒素胁迫紫茎泽兰Eupatorium adenophorum后,叶片及渗漏液中7种矿质元素含量变化。结果表明,毒素胁迫离体叶片和植株后,Ca和K元素含量分别减少65.9%、59.5%和32.9%、53.9%,其他矿质元素Mg、P、Mn、Zn在叶片中的含量有不同程度增加。渗漏液中Ca、K、Fe元素含量较毒素粗提液中含量增加,以Ca元素含量增加最多（近30倍）,Mg、P、Mn、Zn元素含量减少。     

Rebound hyperkalemia in a dog with albuterol toxicosis after cessation of potassium supplementation

Objective

To describe the presentation of rebound hyperkalemia as a delayed side effect of albuterol toxicity in a dog.

Case Summary

A 3-year-old female neutered mixed-breed dog was presented for albuterol toxicosis that led to a severe hypokalemia, hyperlactatemia, and hyperglycemia. The dog also experienced sinus tachycardia and generalized weakness. Treatment was instituted with intravenous fluid therapy and potassium supplementation, and the dog was monitored with a continuous electrocardiogram. Resolution of hypokalemia was documented 12 hours after initial presentation, at which time fluid therapy and potassium supplementation were discontinued. There were no further periods of sinus tachycardia, but instead the dog developed ventricular ectopy with rapid couplets (instantaneous rates of 300/min). An echocardiogram revealed normal cardiac size and function. Twenty-four hours after presentation, the patient developed severe hyperkalemia, despite discontinuation of fluids and potassium supplementation for 12 hours. Serial venous and urinary electrolytes were performed for determination of the fractional excretion of electrolytes. These data confirmed rebound hyperkalemia (7.0 mmol/L), consistent with a markedly increased fractional excretion of potassium, and secondary to the release of potassium from inside the cells. Fluid therapy with dextrose supplementation was provided until 36 hours postpresentation. The hyperkalemia resolved, and the dog was discharged after 44 hours of hospitalization.

New or Unique Information Provided

This case documents rebound hyperkalemia following treatment of albuterol toxicosis in a dog. This case highlights the importance of understanding the distribution of total body potassium when treating serum hypokalemia. Transcellular shifts of potassium, as in the case of albuterol toxicosis, can lead to rebound hyperkalemia even after discontinuation of potassium supplementation. This case further explores the utility of fractional excretion of electrolytes in elucidating the etiology and management of electrolyte disturbances.     

Fractional excretion tests: a critical review of methods and applications in domestic animals

The fractional excretion (FE) of a constituent by the kidney is the fraction of the amount filtered by the glomerulus, which is excreted into urine. It is mostly determined for electrolytes, and is expressed as the ratio of the clearance of a given electrolyte to creatinine clearance. The main physiologic factors affecting FE variation are species, age, and the alimentary supply of electrolytes. The value of FE tests in the diagnosis of kidney disease is limited, except in canine Fanconi's syndrome. FEs of many constituents often are increased in chronic kidney disease, but their diagnostic value is no greater than that of plasma creatinine concentration. FEs also are altered in nonrenal diseases such as diabetes mellitus and rhabdomyolysis, and during treatment with xylazine, rehydration fluids, and diuretics. FEs, especially of calcium, phosphates, and magnesium, are useful in clinical nutrition to assess mineral balance. FE is difficult to measure, so its use should be limited to nutritional investigations and nephrology research.     

家兔实验性酸血症时的心电图变化

选用健康家兔20只,从耳缘静脉注入12％磷酸二氢钠(5ml/kg体重),观察了注药前及注药后20、60、120min及4～5h的心电图和k~+、cl~-、Ca~(++)变化。结果:心电图以P波、Q—T间期、S—T段及T波变化为明显,S—T段的降低、T波的高尖尤为显著;血气分析,部分代偿性及失代偿性酸中毒典型模型约各占50％;血钾由实验前的15.55mg％增至21.3mg％,血钙由实验前的11.72mg％降至8.31mg％,血氯变化轻微。     

自然降温过程中不同结缕草品种电解质渗透率的动态变化

通过连续3个月跟踪观测3个结缕草品种兰引3号Zoysia japonica cv.Lanyin No.3、青岛Z. japonica cv.Qingdao和交大1号Z. japonica cv.Jiaoda No.1在秋冬自然降温条件的电解质渗透率(EL)变化,比较供试的3个结缕草品种的抗寒性差异.结果表明,随着秋冬季节甘肃兰州的旬平均气温不断降低,3个供试材料的叶、茎和根茎电解质渗透率均出现波动,波动幅度兰引3号＜交大1号＜青岛.结合田间物候期的观测,兰引3号抗寒性和坪用性状最好.研究结果为结缕草在生产中的推广和应用提供了理论依据和技术支持.     

低温胁迫对墨西哥玉米幼苗抗寒性的影响

在5和15℃低温胁迫下,对墨西哥玉米Zea mexicana的2种新材料玉米草1号和玉米草2号叶片内部与抗寒性有关的某些生理生化指标在处理6、24、487、2 h后的变化进行了研究。比较了不同低温处理下,不同材料生理指标变化情况,通过变化规律分析2种材料的抗寒性大小。结果表明,从3个生理指标上看,随温度降低,玉米草1号能保持更好的细胞膜完整性和更低的丙二醛含量,并诱导产生更多的脯氨酸,说明玉米草1号比玉米草2号具有更强的耐寒性。