[Effect of shenmai injection on L-type calcium channel of diaphragmatic muscle cells in rats].
OBJECTIVE
To explore the effect of Shenmai Injection (SMI) on L-type calcium channel of diaphragmatic muscle cells in rats.


METHODS
Single diaphragmatic muscle cell of rats was obtained by the acute enzyme isolation method and the standard whole-cell patch clamp technique was used to record the inward peak L-type calcium current (IPLC) and current-voltage relationship curve of diaphragmatic muscle cells of 7 rats, and to compare the effects of SMI in various concentrations on them.


RESULTS
When keeping the electric potential at -80 mV, stimulation frequency 0.5 Hz, clamp time 300 ms, stepped voltage 10 mV, and depolarized to +60 mV, 10 microliters/ml of SMI could only cause the mean IPLC of rat's diaphragmatic muscle cells increased from -6.9 +/- 0.6 pA/pF to -7.5 +/- 0.7 pA/pF, the amplification being (9.2 +/- 2.8)%, comparison between those of pre-treatment and post-treatment showed insignificant difference. But when the concentration of SMI increased to 50 microliters/ml and 100 microliters/ml, the mean IPLC increased to -8.4 +/- 0.6 pA/pF and -9.2 +/- 0.6 pA/pF, respectively, and the amplification was (22.4 +/- 1.7)% and (34.6 +/- 4.6)% respectively, showing significant difference to that of pre-treatment (P < 0.05). However, SMI showed no significant effect on maximal activation potential and reversal potential.


CONCLUSIONS
SMI can activate the calcium channel of diaphragmatic muscle cells in rats, increase the influx of Ca2+, so as to strengthen the contraction of diaphragmatic muscle, which may be one of the ionic channel mechanisms of SMI in treating diaphragmatic muscle fatigue in clinical practice.
D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D003964:Diaphragm / Q000378:metabolism*; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D020746:Calcium Channels, L-Type; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; C009252:fructus schizandrae, radix ginseng, radix ophiopogonis drug combination