Complementary DNA cloning, tissue distribution, and synthesis of canine brain natriuretic peptide

Abstract

Objective - To determine complimentary DNA (cDNA) sequence and tissue distribution of canine brain natriuretic peptide (BNP), and to investigate whether synthesis of canine BNP increases in association with cardiovascular dysfunction. Animals - 5 healthy adult mixed-breed dogs and 3 healthy adult Beagles. Procedure - Total RNA was extracted from normal canine hearts and was used in a reverse transcriptionpolymerase chain reaction (RT-PCR) procedure to isolate canine BNP cDNA. Sequence of the isolated cDNA was analyzed. Gene expression of canine BNP in various tissues from 2 mixed-breed dogs was investigated, using RT-PCR and northern blot analyses. Moreover, messenger RNA (mRNA) expression of canine BNP, using northern blot analysis, was compared between grossly normal hearts from 3 Beagles and hearts from 3 mixed-breed dogs with acute myocardial infarction created by surgical ligation. Results - The cDNA sequence and deduced amino acid residues of canine BNP precursor were 420 base pairs and 140 residues, respectively. Messenger RNA expression of canine BNP was detectable in the atria but not in the ventricles and the other tissues. Messenger RNA expression of canine BNP was, however, detectable in the infarcted portion of the ventricles. The amount of canine BNP mRNA in the infarcted ventricles was significantly increased, compared with that of noninfarcted ventricles. Conclusion - The cDNA sequence of canine BNP was determined. Expression of canine BNP mRNA was detected not only in the atria but also in infarcted ventricles. Synthesis of canine BNP increases in association with ischemic myocardial injury. Canine BNP may be used as an indicator of severity of ventricular myocardial injury.