This study investigates changes in the
messenger RNA (
mRNA) expression levels of HCN2 and HCN4 encoding rat If channels; ClC-3, a candidate gene for swelling-activated Cl- channel, and pICln, a regulatory subunit of Cl- channels in rat hypertrophied heart induced by banding the abdominal aorta. The
mRNA expression levels were quantified with competitive reverse transcription polymerase chain reaction methods. Plasma
renin activity, blood pressure, and heart weight increased. HCN2, HCN4, and ClC-3
mRNA levels decreased in the early phase after banding, whereas they increased in the late phase; pICln
mRNA levels did not change at any stage. Administration of
candesartan, an
angiotensin II receptor blocker, prevented
cardiac hypertrophy, but
amlodipine, a Ca2+ channel blocker, did not prevent it, whereas both drugs lowered blood pressure. Changes in
mRNA levels of HCN2, HCN4, and ClC-3 were alleviated by both
candesartan and
amlodipine, and these levels of the treated groups were not different from those in the
sham control group. This study is the first to demonstrate changes in
mRNA levels of HCN2, HCN4, and ClC-3 in
cardiac hypertrophy induced by abdominal aortic banding. The data further suggest that the changes in channel
mRNA levels were prevented by blood pressure reduction without affecting heart weight increase in this model.