Red Blood Cell Phosphate Concentration and Osmotic Resistance During Dietary Phosphate Depletion in Dairy Cows

Abstract

BackgroundHypophosphatemia in early lactating dairy cows has been implicated as primary cause for postparturient hemoglobinuria in cattle. Decreased availability of phosphorus has been proposed to reduce adenosine triphosphate synthesis of erythrocytes and thereby reduce osmotic resistance of these cells.Hypothesis/ObjectivesTo study the effect of phosphorus depletion on the phosphate concentration ([Pi]) in plasma and erythrocytes and the osmotic resistance of erythrocytes and to determine the association between plasma [Pi] and erythrocyte [Pi].AnimalsTen healthy midlactating dairy cows in their 3rd to 5th lactation.MethodsProspective study. Dietary phosphorus depletion for 5 weeks followed by phosphorus supplementation. Plasma and erythrocyte [Pi] and erythrocyte osmotic resistance were measured. Four cows underwent continuous dextrose infusion at the end of phosphate depletion to exacerbate hypophosphatemia.ResultsDietary P depletion resulted in a marked decline of the plasma [Pi] from 4.1 ± 1.0 mg/dL to a nadir of 1.7 ± 0,5 mg/dL, but did not alter erythrocyte [Pi] or osmotic resistance. Similarly, dextrose infusion induced a decline of the plasma [Pi] from 2.4 ± 0.5 mg/dL to 1.5 ± 0.5 mg/dL, but had no effect on erythrocyte [Pi] or osmotic resistance.Conclusions and Clinical ImportanceIn cattle, marked hypophosphatemia induced by dietary P depletion was neither associated with a decline in erythrocyte [Pi] nor with decreased osmotic resistance of erythrocytes. Phosphorus depletion alone is therefore unlikely to cause intravascular hemolysis and the plasma [Pi] is an unreliable index for the intracellular [Pi] of erythrocytes.

Concentration of Potassium in Plasma, Erythrocytes, and Muscle Tissue in Cows with Decreased Feed Intake and Gastrointestinal Ileus

“…Then an approximately 200 mg muscle biopsy specimen was obtained using the biopsy needle7, put into the sample vial9 which was tightly closed and analyzed for tissue potassium (IDEXX laboratories Germany). Biopsy specimens were kept at room temperature until analyzed similar to studies which have been published recently 18, 19, 20. The analysis was performed within 48 hours of sample collection.…”

“…The potassium measurement in blood plasma was performed at the laboratory of the clinics for ruminants using an ISE incorporated in a blood gas analysis device 5. The potassium concentration in tissue and in the erythrocytes were measured by one of the authors (Dr. Anja Müller, Vet Med Labor GmhH, Division of IDEXX Laboratories, Germany) using inductively coupled plasma optical emission spectroscopy (ICP‐OES)13 which has been described previously 18, 19, 20. Dr. Müller was blinded to the origin of the samples.…”

Post parturient hemoglobinuria in a sheep flock

“…This can suggest that hypophosphatemia is not the solely responsible for PPH. Grunberg et al (2015) showed that experimental hypophosphatemia alone was not associated with intravascular hemolysis in cattle (Grunberg et al, 2015). In this study, PPH occurred in hypophosphatemic ewes following frozen pasture grazing.…”

Anaemia in a llama (Lama glama): treatment, regeneration and differential diagnoses

“…Haemolytic anaemia has been observed in human beings and cows with hypophosphataemia 38 39. However, haemolysis in those cases might be multifactorial and not be reduced to hypophosphataemia 40. Hypophosphataemia may be taken into account as a predisposing factor for developing anaemia, but seems to be an additional finding in the present case.…”