Effect of chronic electrical stimulation of phrenic nerve at different frequencies on mRNA and protein expression of skeletal DHPR(alpha1) and RyRs in the diaphragm muscle of rabbits / 生理学报

ABSTRACT

The mRNA and protein expression of skeletal dihydropyridine receptor isoform alpha1 subunit (DHPR(alpha1)) and ryanodine receptor(1-3) (RyR(1-3)) during chronic electrical stimulation (CES) of phrenic nerve have rarely been explored. In the present study, we explored the signal translation mode of calcium release unit in diaphragm muscle of rabbits after CES. Thirty rabbits were used and randomly divided into the normal, 10, 20, 50 and 100 Hz groups. Phrenic nerve was continuously (5 weeks, 2x 2 h/d) stimulated at 10, 20, 50 and 100 Hz respectively (impulse width 0.2 ms, 3~6 waves/time, 45 times/min, 10~20 V). Reverse transcription PCR and immunohistochemical methods were employed. The results showed that mRNA and protein expressions of DHPR(alpha1) and RyR(1) in 10 and 20 Hz groups were more significantly lower than those in the control group (P<0.01), but mRNA and protein expressions of DHPR(alpha1) and RyR(1) were significantly higher in 50 and 100 Hz groups than those in the control group (P<0.01); a lower level of mRNA expression of RyR(2) was found in 10 and 20 Hz groups. It is suggested that the calcium release unit and the signal transduction mode between DHPR and RyRs were altered from conformational changes of linked proteins to Ca(2+)-induced Ca(2+) release (CICR) in the diaphragmatic muscle of rabbits after chronic low-frequency electrical stimulation of phrenic nerve for 5 weeks.