Effects of motor nerve anesthesia and tenotomy on muscle membrane properties

Abstract

Motor nerves to soleus muscles of rats were kept anesthetized for up to 7 days by applying solutions of lidocaine base or marcaine HCl. The anesthetic solutions were delivered from a subcutaneously located ALZA-minipump and reached the nerves through silastic cuffs. The ACh supersensitivity of muscles inactivated by nerve anesthesia for 3–7 days was comparable to that of muscles denervated for the same length of time.g _m/g_k (the ratio of total membrane conductance to the membrane K conductance) decreased from a normal value of 5–10 to less than two in 6–7 days, in anesthetic-inactivated and denervated muscles. The results were variable after 3 days of anesthesia.g _m/g_k of muscles which were tenotomized for 3 weeks was unchanged. The voltage-current curve for muscles kept in a solution containing 50 mM K propionate, which is steep at +50 mV, was less steep in denervated and anesthetic-inactivated, but not in tenotomized muscles, although atrophy was marked in all non-normal muscles.