Rapid activation of the type B versus type A natriuretic factor gene by aortocaval shunt induced cardiac volume overload.
OBJECTIVE
The aim was to compare activities of the type A and type B natriuretic factor genes during development of cardiac hypertrophy by use of a non-radioactive method designed for assessment of stable atrial and brain natriuretic factor (ANF, BNF) transcript levels in biopsy sized tissue samples.


METHODS
At 1 and 7 days after aortocaval shunt or sham surgery in rats, quantitative reverse transcriptase mediated polymerase chain reaction (Q-RT-PCR) was used to determine mRNA levels in cardiac tissues. Phosphoglycerate kinase-1 (PGK-1) mRNA levels served as an external standard for Q-RT-CR.


RESULTS
The shunt increased left ventricular end diastolic pressure at days 1 and 7, and cardiac weight was increased by day 7. By day 1, left ventricular BNF mRNA levels were twice those of controls, whereas ANF mRNA levels were not changed. By day 7, left ventricular BNF mRNA levels were increased 15-fold, and those for ANF were increased fivefold; the BNF mRNAs were also increased in right atria and right ventricle, about fivefold in both cases.


CONCLUSIONS
Both natriuretic factor genes were activated by cardiac volume overload, and the increase in the level of left ventricular BNF transcripts-observed for the first time-was in fact more rapid and exceeded that of ANF. The Q-RT-PCR assay will be of value to investigate the response to increased work load of cardiac muscle in vivo.
Lear
W
W
University of Ottawa Heart Institute Research Centre, Ontario, Canada.
Boer
P H
PH
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics*; D001483:Base Sequence; D006332:Cardiomegaly / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D005786:Gene Expression Regulation; D008297:Male; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D051381:Rats; D017208:Rats, Wistar
D017931:DNA Primers; D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor