Avtor/Urednik		Toplišek, J
Naslov		Uravnavanje acetilholinesteraze med ponovnim oživčenjem skeletne mišice
Prevedeni naslov		Regulation of acetylcholinesterase during reinnervation of skeletal muscle
Tip		članek
Vir		Med Razgl
Vol. in št.		Letnik 33, št. 4
Leto izdaje		1994
Obseg		str. 443-61
Jezik		slo
Abstrakt		Abstract. In a muscle fibre, regulation of syn- thesis of motor endplate macromolecules chan- ges during ontogenetic development. Immature early postnatal muscles of rat can synthesize the asymmetric forms of acetylcholinesterase (AChE) and the molecules of acetylcholine receptor (AChR) also in the endplate free regions. Synthesis of ACh R in the endplate free regions is suppressed by the end of the first week, and synthesis of the asymmetric forms of AChE by the fourth week of postnatal development. After denervation of a mature muscle, synthesis of ACh R, but not of the asymmetric forms of AChE, is restored in its endplate free regions. Therefore, we assumed that the muscle must be reinner- vated. Molecular forms of AChE were separat- ed by velocity sedimentation in linear sucrose gra- dients. Temporary denervation was achieved by crush lesion to the sciatic nerve. Disuse of the muscle was produced by immobilisation of hind leg joints, while transitory paralysis was induced by a-bungarotoxin administrating. Activity of the asymmetric AChE forms in the endplate free regions was transiently greatly increased by reinnervation of the slow soleus muscle - the muscle reverted to immature postnatal-like state. Transient paralysis of solens muscle due to ACh R blockade, followed by reactivation of the muscle, did not trigger that event. The maintenance of immature state requires permanent innervation. Tonic pattern of motor nerve firing is not crucial for this phenomenon to occur. The fast extensor digitorum longus muscle did not return to imma- ture state atter reinnervation. The observed dif- ference between fast and slow muscles is prob- ably based on the intrinsic, i.e. genetic, difference between the two types of muscles.
Izvleček		Izvlećek. V mišičnem vlaknu se uravnavanje tvorbe makromolekul motorične ploščice spre- minja med ontogenetskim razvojem. Za nezrele postnatalne mišice podgane je značilno, da se nesimetrične molekularne oblike acetilholinesteraze (AChE) in molekule acetilholinskega receptorja (AChR) sintetizirajo tudi izven motoričnih ploščic. Izven ploščic se sinteza ACh R za- vre v prvem tednu, sinteza nesimetričnih oblik AChE pa v četrtem tednu postnatalnega razvoja. Po denervaciji zrele mišice pride v izvenploščičnih predelih do ponovne tvorbe in vgrajevanja AChR, ne pa tudi nesimetričnih oblik ACh E. Domnevali smo, da mišica za to morda potrebuje ponovno oživčenje. Molekularne oblike AChE smo ločevali po hitrosti sedimentacije v linearnem saharoznem gradientu. Prehodno denervacijo smo dosegli s pretisnjenjem ishiadičnega živca. Nerabo mišice smo povzročili z imobilizacijo sklepov na zadnji okončini, začasno paralizo pa z a-bungarotoksinom. Reinervacija počasne mišice soleus povzroči prehodno močno povečanje aktivnosti nesimetrične oblike AChE 16S v izvenploščičnih predelih, kar ustreza vrnitvi mišice v nezrelo postnatalno stanje. Začasna paraliza zaradi blokade ACh R, ki ji sledi reaktivacija mišice, ne sproži takega dogajanja. Za vzdrževanje nezrelega stanja je nujna stalna prisotnost oživčenja mišice. Tonični vzorec proženja motoričnega živca ni odločilen za ta pojav. Hitra mišica ekstenzor digitorum longus se med reinervacijo ne vrne v nezrelo stanje. Opažena razlika med hitro in poćasno mišico verjetno temelji na genetsko pogojeni, intrinzični razliki med mišicama.
Deskriptorji		MOTOR ENDPLATE EXTREMITIES ACETYLCHOLINESTERASE RATS MUSCLE DENERVATION NERVE REGENERATION