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Pharmaceutical Research

, Volume 24, Issue 9, pp 1653–1659 | Cite as

Increased Erythropoietin Elimination in Fetal Sheep Following Chronic Phlebotomy

  • Kevin. J. Freise
  • John A. Widness
  • Jeffrey L. Segar
  • Robert L. Schmidt
  • Peter Veng-Pedersen
Research Paper

Abstract

Purpose

To determine by pharmacokinetic (PK) means the role of erythropoietin-receptor (EPO-R) upregulation in fetuses on the elimination of erythropoietin (EPO).

Materials and Methods

Six fetal sheep were catheterized at a gestational age of 125–127 days and phlebotomized daily for 6 days. Paired tracer PK studies using recombinant human EPO (rHuEPO) were conducted in the sheep fetuses at baseline and post-phlebotomy, 7 days later. A PK model with Michaelis-Menten elimination was simultaneously fit to the PK data at baseline and post-phlebotomy for each fetus.

Results

Daily phlebotomies reduced the hemoglobin levels from baseline values of 10.8 (5%) (mean (C.V.)) g/dl to a nadir of 4.5 (17%) g/dl post-phlebotomy. The endogenous EPO concentration rapidly increased after the first phlebotomy and remained elevated, although variable, thereafter. The Michaelis-Menten maximal rHuEPO elimination rate parameter, Vmax, was significantly greater post-phlebotomy than at baseline (p < 0.05), increasing 1.31 fold. The fetal baseline “linear” clearance at very low concentrations of rHuEPO was determined to be 117 ml/kg/h, similar to that determined in newborn sheep but 2–3 fold higher than that determined in adult sheep.

Conclusions

The observed increase in Vmax is consistent with an up-regulation of EPO-R due to a positive feedback resulting from the phlebotomy-induced anemia.

Key words

developmental comparison erythropoietin receptors fetus pharmacokinetics  receptor regulation 

Abbreviations

125I-rHuEPO

125I-labeled rHuEPO

BFU-E

burst forming unit-erythroid

CFU-E

colony forming unit-erythroid

Cl

clearance at “very low” concentrations

CL

plasma 125I- rHuEPO concentration in cpms/ml (labeled)

CRI

constant rate infusion

CU

plasma rHuEPO concentration in mU/ml (unlabeled)

DL

IV bolus 125I- rHuEPO loading dose

EPO

erythropoietin

EPO-R

erythropoietin receptor

Hb

hemoglobin

IV

intravenous

k12

first order rate constant of distribution out of the central compartment

k21

first order rate constant of distribution into the central compartment

km

plasma rHuEPO concentration where 50% of Vmax occurs

PD

pharmacodynamic

PK

pharmacokinetic

R

IV infusion rate of 125I-rHuEPO

RhuEPO

recombinant human erythropoietin

t0

initial time

TIM

tracer interaction method

V

apparent volume of distribution

Vmax

maximal rate of rHuEPO elimination

Z

125I- rHuEPO distribution variable

Notes

Acknowledgements

The rabbit antiserum used in the erythropoietin radioimmunoassay was a generous gift from Gisela K. Clemons, PhD. This work is supported by United States Public Health Service, National Institute of Health grants R01 HL-64770 (JLS) and P01 HL49625 (JAW).

References

  1. 1.
    R. Hoffman, E. J. Benz Jr., S. J. Shattil, B. Furie, H. J. Cohen, L. E. Silberstein, and P. McGlave. Hematology: Basic Principles and Applications, Elsevier, USA, 2005.Google Scholar
  2. 2.
    J. W. Fisher. Erythropoietin: physiology and pharmacology update. Exp. Biol. Med. (Maywood) 228:1–14 (2003).Google Scholar
  3. 3.
    J. Rossert and K. U. Eckardt. Erythropoietin receptors: their role beyond erythropoiesis. Nephrol. Dial. Transplant. 20:1025–1028 (2005).PubMedCrossRefGoogle Scholar
  4. 4.
    M. Brines and A. Cerami. Discovering erythropoietin’s extra-hematopoietic functions: biology and clinical promise. Kidney Int. 70:246–250 (2006).PubMedCrossRefGoogle Scholar
  5. 5.
    K. Sawada, S. B. Krantz, C. H. Dai, S. T. Koury, S. T. Horn, A. D. Glick, and C. I. Civin. Purification of human blood burst-forming units-erythroid and demonstration of the evolution of erythropoietin receptors. J. Cell Physiol. 142:219–230 (1990).PubMedCrossRefGoogle Scholar
  6. 6.
    J. W. Adamson. Regulation of red blood cell production. Am. J. Med. 101:4S–6S (1996).PubMedCrossRefGoogle Scholar
  7. 7.
    J. H. Jandl. Blood: Textbook of Hematology, Little Brown, USA, 1996.Google Scholar
  8. 8.
    S. T. Sawyer, S. B. Krantz, and E. Goldwasser. Binding and receptor-mediated endocytosis of erythropoietin in Friend virus-infected erythroid cells. J. Biol. Chem. 262:5554–62 (1987).PubMedGoogle Scholar
  9. 9.
    D. L. Beckman, L. L. Lin, M. E. Quinones, and G. D. Longmore. Activation of the erythropoietin receptor is not required for internalization of bound erythropoietin. Blood 94:2667–75 (1999).PubMedGoogle Scholar
  10. 10.
    S. T. Sawyer and W. D. Hankins. The functional form of the erythropoietin receptor is a 78-kDa protein: correlation with cell surface expression, endocytosis, and phosphorylation. Proc. Natl. Acad. Sci. U. S. A. 90:6849–6853 (1993).PubMedCrossRefGoogle Scholar
  11. 11.
    M. Kato, H. Kamiyama, A. Okazaki, K. Kumaki, Y. Kato, and Y. Sugiyama. Mechanism for the nonlinear pharmacokinetics of erythropoietin in rats. J. Pharmacol. Exp. Ther. 283:520–527 (1997).PubMedGoogle Scholar
  12. 12.
    W. Jelkmann. The enigma of the metabolic fate of circulating erythropoietin (Epo) in view of the pharmacokinetics of the recombinant drugs rhEpo and NESP. Eur. J. Haematol. 69:265–274 (2002).PubMedCrossRefGoogle Scholar
  13. 13.
    M. Kato, Y. Kato, and Y. Sugiyama. Mechanism of the upregulation of erythropoietin-induced uptake clearance by the spleen. Am. J. Physiol. 276:E887–E895 (1999).PubMedGoogle Scholar
  14. 14.
    H. Kinoshita, N. Ohishi, S. Tokura, and A. Okazaki. Pharmacokinetics and distribution of recombinant human erythropoietin in rats with renal dysfunction. Arzneim-Forsch/Drug Res. 42(I):682–686 (1992).Google Scholar
  15. 15.
    J. A. Widness, P. Veng-Pedersen, C. Peters, L. M. Periera, R. L. Schmidt, and L. S. Lowe. Erythropoietin pharmacokinetics in premature infants: developmental, nonlinearity, and treatment effects. J. Appl. Physiol. 80:140–148 (1996).PubMedGoogle Scholar
  16. 16.
    T. Sans, J. Joven, E. Vilella, G. Masdeu, and M. Farre. Pharmacokinetics of several subcutaneous doses of erythropoietin: potential implications for blood transfusion. Clin. Exp. Pharmacol. Physiol. 27:179–184 (2000).PubMedCrossRefGoogle Scholar
  17. 17.
    P. Veng-Pedersen, S. Chapel, N. H. Al-Huniti, R. L. Schmidt, E. M. Sedars, R. J. Hohl, and J. A. Widness. Pharmacokinetic tracer kinetics analysis of changes in erythropoietin receptor population in phlebotomy-induced anemia and bone marrow ablation. Biopharm. Drug Dispos. 25:149–156 (2004).PubMedCrossRefGoogle Scholar
  18. 18.
    S. H. Chapel, P. Veng-Pedersen, R. L. Schmidt, and J. A. Widness. Receptor-based model accounts for phlebotomy-induced changes in erythropoietin pharmacokinetics. Exp. Hematol. 29:425–431 (2001).PubMedCrossRefGoogle Scholar
  19. 19.
    S. Chapel, P. Veng-Pedersen, R. J. Hohl, R. L. Schmidt, E. M. McGuire, and J. A. Widness. Changes in erythropoietin pharmacokinetics following busulfan-induced bone marrow ablation in sheep: evidence for bone marrow as a major erythropoietin elimination pathway. J. Pharmacol. Exp. Ther. 298:820–824 (2001).PubMedGoogle Scholar
  20. 20.
    P. Veng-Pedersen, S. Chapel, N. H. Al-Huniti, R. L. Schmidt, E. M. Sedars, R. J. Hohl, and J. A. Widness. A differential pharmacokinetic analysis of the erythropoietin receptor population in newborn and adult sheep. J. Pharmacol. Exp. Ther. 306: 532–537 (2003).PubMedCrossRefGoogle Scholar
  21. 21.
    M. Cazzola, R. Guarnone, P. Cerani, E. Centenara, A. Rovati, and Y. Beguin. Red blood cell precursor mass as an independent determinant of serum erythropoietin level. Blood 91:2139–2145 (1998).PubMedGoogle Scholar
  22. 22.
    Y. Beguin, G. K. Clemons, P. Pootrakul, and G. Fillet. Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin. Blood 81:1067–1076 (1993).PubMedGoogle Scholar
  23. 23.
    G. de Klerk, P. C. Rosengarten, R. J. Vet, and R. Goudsmit. Serum erythropoietin (EST) titers in anemia. Blood 58:1164–1170 (1981).PubMedGoogle Scholar
  24. 24.
    S. E. Juul, A. T. Yachnis, and R. D. Christensen. Tissue distribution of erythropoietin and erythropoietin receptor in the developing human fetus. Early Hum. Dev. 52:235–249 (1998).PubMedCrossRefGoogle Scholar
  25. 25.
    F. Farrell and A. Lee. The erythropoietin receptor and its expression in tumor cells and other tissues. Oncologist. 9(Suppl. 5):18–30 (2004).PubMedCrossRefGoogle Scholar
  26. 26.
    J. A. Widness, P. Veng-Pedersen, N. B. Modi, R. L. Schmidt, and D. H. Chestnut. Developmental differences in erythropoietin pharmacokinetics: Increased clearance and distribution in fetal and neonatal sheep. J. Pharmacol. Exp. Ther. 261:977–984 (1992).PubMedGoogle Scholar
  27. 27.
    M. S. Brown, M. A. Jones, R. K. Ohls, and R. D. Christensen. Single-dose pharmacokinetics of recombinant human erythropoietin in preterm infants after intravenous and subcutaneous administration. J. Pediatr. 122:655–657 (1993).PubMedCrossRefGoogle Scholar
  28. 28.
    P. Veng-Pedersen, J. A. Widness, J. Wang, and R. L. Schmidt. A tracer interaction method for nonlinear pharmacokinetics analysis: application to evaluation of nonlinear elimination. J. Pharmacokinet. Biopharm. 25:569–593 (1997).PubMedCrossRefGoogle Scholar
  29. 29.
    R. Ramakrishnan, W. K. Cheung, M. C. Wacholtz, N. Minton, and W. J. Jusko. Pharmacokinetic and pharmacodynamic modeling of recombinant human erythropoietin after single and multiple doses in healthy volunteers. J. Clin. Pharmacol. 44:991–1002 (2004).PubMedCrossRefGoogle Scholar
  30. 30.
    P. Veng-Pedersen, J. A. Widness, L. M. Pereira, R. L. Schmidt, and L. S. Lowe. A comparison of nonlinear pharmacokinetics of erythropoietin in sheep and humans. Biopharm. Drug Dispos. 20:217–223 (1999).PubMedCrossRefGoogle Scholar
  31. 31.
    P. Veng-Pedersen, J. A. Widness, L. M. Pereira, C. Peters, R. L. Schmidt, and L. S. Lowe. Kinetic evaluation of nonlinear drug elimination by a disposition decomposition analysis. Application to the analysis of the nonlinear elimination kinetics of erythropoietin in adult humans. J. Pharm. Sci. 84:760–767 (1995).PubMedCrossRefGoogle Scholar
  32. 32.
    J. J. Jennings and J. P. Crowley. The influence of mating management on fertility in ewes following progesterone-PMS treatment. Vet. Rec. 90:495–498 (1972).PubMedGoogle Scholar
  33. 33.
    J. L. Segar, K. Bedell, W. V. Page, J. E. Mazursky, A. M. Nuyt, and J. E. Robillard. Effect of cortisol on gene expression of the renin-angiotensin system in fetal sheep. Pediatr. Res. 37:741–746 (1995).PubMedCrossRefGoogle Scholar
  34. 34.
    J. A. Widness, R. L. Schmidt, P. Veng-Pedersen, N. B. Modi, and S. T. Sawyer. A sensitive and specific erythropoietin immunoprecipitation assay: application to pharmacokinetic studies. J. Lab. Clin. Med. 119:285–294 (1992).PubMedGoogle Scholar
  35. 35.
    M. F. Hutchinson, and F. R. deHoog. Smoothing noise data with spline functions. Numer. Math. 47:99–106 (1985).CrossRefGoogle Scholar
  36. 36.
    H. Akaike. Automatic control: A new look at the statistical model identification. IEEE Trans. 19:716–723 (1974).Google Scholar
  37. 37.
    P. Veng-Pedersen. Curve fitting and modelling in pharmacokinetics and some practical experiences with NONLIN and a new program FUNFIT. J. Pharmacokinet. Biopharm. 5:513–531 (1977).CrossRefGoogle Scholar
  38. 38.
    S. H. Chapel, P. Veng-Pedersen, R. L. Schmidt, and J. A. Widness. A pharmacodynamic analysis of erythropoietin-stimulated reticulocyte response in phlebotomized sheep. J. Pharmacol. Exp. Ther. 295:346–351 (2000).PubMedGoogle Scholar
  39. 39.
    P. Veng-Pedersen, S. Chapel, R. L. Schmidt, N. H. Al-Huniti, R. T. Cook, and J. A. Widness. An integrated pharmacodynamic analysis of erythropoietin, reticulocyte, and hemoglobin responses in acute anemia. Pharm. Res. 19:1630–1635 (2002).PubMedCrossRefGoogle Scholar
  40. 40.
    N. H. Al-Huniti, J. A. Widness, R. L. Schmidt, and P. Veng-Pedersen. Pharmacodynamic analysis of changes in reticulocyte subtype distribution in phlebotomy-induced stress erythropoiesis. J. Pharmacokinet. Pharmacodyn. 32:359–376 (2005).PubMedCrossRefGoogle Scholar
  41. 41.
    R. A. Brace. Blood volume and its measurement in the chronically catheterized sheep fetus. Am. J. Physiol. 244: H487–H494 (1983).PubMedGoogle Scholar
  42. 42.
    A. C. Guyton, and J. E. Hall. Textbook of Medical Physiology, Saunders, Philadelphia, 2000.Google Scholar
  43. 43.
    R. S. Hillman, K. A. Ault, and H. M. Rinder. Hematology in Clinical Practice, McGraw-Hill, USA, 2005.Google Scholar
  44. 44.
    R. V. Pierre. Reticulocytes. Their usefulness and measurement in peripheral blood. Clin. Lab. Med. 22:63–79 (2002).PubMedCrossRefGoogle Scholar
  45. 45.
    C. Brugnara. Use of reticulocyte cellular indices in the diagnosis and treatment of hematological disorders. Int. J. Clin. Lab. Res. 28:1–11 (1998).PubMedCrossRefGoogle Scholar
  46. 46.
    A. Major, C. Bauer, C. Breymann, A. Huch, and R. Huch. rh-erythropoietin stimulates immature reticulocyte release in man. Br. J. Haematol. 87:605–608 (1994).PubMedGoogle Scholar
  47. 47.
    J. K. Chamberlain, L. Weiss, and R. I. Weed. Bone marrow sinus cell packing: a determinant of cell release. Blood. 46:91–102 (1975).PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Kevin. J. Freise
    • 1
  • John A. Widness
    • 2
  • Jeffrey L. Segar
    • 2
  • Robert L. Schmidt
    • 2
  • Peter Veng-Pedersen
    • 1
  1. 1.College of PharmacyThe University of IowaIowa CityUSA
  2. 2.Department of Pediatrics, College of MedicineThe University of IowaIowa CityUSA

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