AIMTo record funny currents (If) of ventricular myocytes and to analysize hyperpolarization-activated cation channel(HCN) expression in the rats of different ages.

METHODSFresh ventricular myocytes were isolated from 3 days rats and adult rats.HCN expressions were measured by real-time quantitative polymerase chain reaction(real-time PCR). It was recorded through whole-cell patch clamp.

RESULTSHCN1, HCN2, HCN3, HCN4 mRNA represented 0.23% +/- 0.01%, 83.58% +/- 0.04%, 0.79% +/- 0.01%, 15.44% +/- 0.01% of total HCN mRNA in the neonatal rats, respectively. If was recorded and the threshold for activation was -75 mV. In the adult rat, HCN1, HCN2, HCN3, HCN4 mRNA represented 0.72% +/- 0.02%, 91.58% +/- 0.08%, 0.27% +/- 0.02%, 7.12% +/- 0.02% of total HCN mRNA. The ratio of HCN2 to HCN4 was approximately (13.06 +/- 0.21):1. The threshold for activation of If was approximately -115 mV in the adult rats.

CONCLUSIONWith the development of rats, the value of If is smaller. The threshold for activation of If is more negative. The ratio of HCN2 to HCN4 is bigger.

Age Factors ; Animals ; Animals, Newborn ; Cells, Cultured ; Cyclic Nucleotide-Gated Cation Channels ; metabolism ; physiology ; Heart Ventricles ; cytology ; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels ; Ion Channels ; metabolism ; Myocytes, Cardiac ; cytology ; physiology ; Patch-Clamp Techniques ; Potassium Channels ; metabolism ; physiology ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley