Biomedical subjects

Zhi-bin Yu

Publications and source records attributed to Zhi-bin Yu.

3 recordsLinked to original sources

PubMed2005

[Effects of nifedipine on myosin heavy chain (MHC) isoforms transition in unloaded soleus].

OBJECTIVE: To observe the effects of nifedipine, a blocker of L-type Ca2+ channel, on soleus weight and expression of myosin heavy chain (MHC) isoforms in control and tail-suspended rats. METHOD: Animals were treated with nifedipine at a dose of 10 mg/kg per day in drinking water for 1 or 2 weeks. The expression of MHC isoform protein was observed by SDS-polyacrylamide gel electrophoresis at 4 degrees C. The expression of MHC mRNA was detected by RT-PCR. RESULT: The relative weight (muscle weight/body weight) of soleus muscle was decreased by 39.5% and 51.7% in 1 and 2 weeks of tail-suspended group respectively, but no changes in extensor digitorum longus (EDL) weight was found. The relative weight of soleus and EDL in 1 or 2 weeks of nifedipine treated control group showed no changes as compared with the untreated control group. The relative weight of soleus in 1 or 2 weeks of nifedipine treated tail-suspension group decreased by 36.6% or 52.0%, respectively, as compared with control, but there was no difference between tail-suspension group with or without nifedipine treatment. The expression of MHC I, IIa mRNA and protein could be detected in control soleus with or without nifedipine treatment. The expression MHC I, IIa, IIx and IIb mRNA was detected in 1 or 2 weeks of unloaded soleus with or without nifedipine treatment. Nifedipine inhibited the expression of II type MHC mRNA in unloaded soleus and expression of MHC IIa protein in control and unloaded soleus. CONCLUSION: Nifedipine can not resist atrophy of unloaded soleus, but inhibit the transition of MHC from slow to fast isoforms at the transcription level.

Animals↗

PubMed2002

[Decrease in tetanic tension in 4-week tail-suspended rat soleus and analysis of its underlying mechanisms].

Objective. To observe the dynamic changes in tetanic tension in 4-week tail-suspended rat soleus (SOL) and extensor digitorum longus muscle (EDL) and to elucidate its underlying mechanisms. Method. After 4 weeks of tail suspension SOL and EDL of the rats were isolated and perfused. Their isometric twitch and tetanic tensions were recorded. Result. Atrophy occurred in the SOL, but not in the EDL. The maximum twitch tension (Pt) decreased significantly and was more dependent on stimulation voltage in SOL of tail-suspended rat. Time to maximum twitch tension (TPT) and time from maximum twitch tension to half relaxation (TR50) were reduced in the SOL. Pt also decreased in the EDL, but TPT and TR50 did not change in the EDL. The maximum tetanic tension reduced in SOL and EDL of tail-suspended rats. The decline rate of tetanic tension in SOL was faster than the control. The profile of tetanic contraction curve in atrophic SOL approached that in EDL. Conclusion. The above results suggested that the underlying mechanisms of reduced maximum twitch and tetanic tension in 4-week tail-suspended rat SOL may involve the reduction in number of cross-bridge per cross-section area or force produced per cross-bridge. The rapid decline rate in atrophic SOL may be related to the shift in myosin heavy chain and troponin I isoforms or to decrease in excitability.

Animals↗

PubMed2002

[Expression of myosin heavy chain IIx mRNA as a molecular marker of disuse of soleus muscle in rats].

Objective. To make an Achilles tenotomy rat model to observe the change in soleus weight and expression of myosin heavy chain (MHC) isoform mRNA, and to find some clues for elucidating the mechanisms of soleus disuse. Method. Thirty male Sprague-Dawley [correction of Sprangue] rats were divided into 6 groups. On the lst, 3rd, 7th, 14th, 21st and 28th days after Achilles tenotomy, wet weight of soleus (SOL), plantaris (PL), gastrocnemius mediales (MG), and gastrocnemius lateral (LG) muscles were measured. Expression of MHC IIx mRNA was observed by means of reverse transcriptase-polymerase chain reaction (RT-PCR). Result. Wet weight of SOL, MG, LG, and PL decreased significantly on the 3rd day after the tenotomy. The wet weight of these muscles reduced to the minimum on the 7th or 14th days after the tenotomy, and then recovered slightly on the 21st day after the tenotomy. There was only the expression of MHC I and MHC IIa mRNA in normal soleus muscle, but no MHC IIx or MHC IIb mRNA. The expression of MHC IIx mRNA occurred in SOL on the 3rd day after tenotomy and still expressed on the 28th day after tenotomy. There was no expression of MHC IIb mRNA in SOL after Achilles tenotomy. Conclusion. The appearance of atrophy of rat soleus induced by Achilles tenotomy is similar in time and extent with that induced by tail-suspension. The expression of MHC IIx mRNA is shown in rat soleus muscles in Achilles tenotomy and tail-suspension models. The study suggests that expression of MHC IIx mRNA may be used as a molecular marker of soleus muscle disuse in rats.

Achilles Tendon↗