Drugs affecting the hematologic system of the performance horse

Nucleotide sequence of equine erythropoietin and characterization of region-specific antibodies

OBJECTIVE

To determine the full-length complementary DNA (cDNA) sequence of equine erythropoietin (EPO) and to develop region-specific antibodies to differentiate equine EPO (eEPO) and human EPO (hEPO).

SAMPLE POPULATION

RNA and lysate extracted from renal tissues of an adult Thoroughbred.

PROCEDURE

Full-length cDNA was determined by use of a reverse transcriptase-polymerase chain reaction assay and a rapid amplification of cDNA ends method. The deduced amino acid sequence was compared with sequences of EPO reported for other species. Furthermore, 4 synthetic peptides were designed in 2 distinctive parts of the eEPO and hEPO amino acid sequences to obtain antibodies specific for eEPO and hEPO. Specificity of the antibodies was tested against supernatant of homogenized equine kidney and recombinant hEPO (rhEPO) by use of western immunoblotting techniques.

RESULTS

Analysis of the 1,181 bp in the nucleotide sequence revealed that eEPO was a residue of 192 amino acids. Similarity of eEPO with amino acid sequences of EPO from other species was 81.0% to 90.6%. Antibodies were specifically recognized by eEPO or rhEPO molecules. Anti-hEPO (161 to 165) antibody specifically recognized rhEPO. In contrast, anti-eEPO (133 to 144) antibody reacted with the equine kidney lysate.

CONCLUSIONS AND CLINICAL RELEVANCE

We determined the cDNA and amino acid sequence of eEPO and developed region-specific antibodies that specifically recognized eEPO or rhEPO. These antibodies may be useful in distinguishing rhEPO from eEPO in a test to detect the misuse of rhEPO in racehorses.

The endocrine system and the challenge of exercise

Fine-tuning of the response to exercise that lasts longer than a few seconds is reliant on the regulation of several key variables governing the cardiopulmonary, vascular, and metabolic response to exercise. This type of integrative response requires communication between organ systems that relies on the secretion of endocrine and paracrine substances by one tissue or organ that are transported remotely to other tissues or organs to evoke a response to adjust to the disturbance.