We studied the effects of the local anesthetics, procaine and benzocaine, on the action potential and force of canine ventricular muscle and Purkinje fibers. In ventricular muscle, procaine often shifted the plateau to a more positive value and increased the force of contraction, whereas benzocaine shortened the action potential and decreased contractile force. In Purkinje fibers, both local an...

Five monoclonal antibodies specific for the 260 kDa subunit of the rat skeletal muscle sodium channel were used to probe the distribution of this channel in adult muscle. All the antibodies reacted with the surface membrane of fast- and slow-twitch fibers in the rat anterior tibial and soleus muscles. Immunoreactivity was also present in the endplate region; this was significantly more intense ...

We appreciate the comments Schachar made on human accommodative ciliary muscle configuration. We agree with the author that the ciliary muscle image in our Figure 2B1 appears to show notching of the anterior radial muscle fibers in the accommodative eye. This observation may be interpreted as the movement of the anterior radial muscle fibers. We thank the author for bringing up this important i...

Skeletal muscle possesses regenerative capacity due to tissue-resident, muscle-fiber-generating (myogenic) satellite cells (SCs), which can form new muscle fibers under the right conditions. Although SCs can be harvested from muscle tissue and cultured in vitro, the resulting myoblast cells are not very effective in promoting myogenesis when transplanted into host muscle. Surgically exposing th...

The adaptation of a slow (soleus, Sol) and a fast (medial gastrocnemius, MG) skeletal muscle to spaceflight was studied in five young male rats. The flight period was 12.5 days and the rats were killed approximately 48 h after returning to 1 g. Five other rats that were housed in cages similar to those used by the flight rats were maintained at 1 g for the same period of time to serve as ground...

A bstract. An immunohistochemical study using monoclonal antibodies specific for the heavy chains ofeither human atrial (HCa) or ventricular (HC(#) myosin was performed to clarify the distribution ofeach isozyme in normal as well as pressure-overloaded human hearts. In normal human ventricles, all muscle fibers were stained by a monoclonal antibody (HMC14) specific for HC(, whereas a small numb...

The principal aim of this work was to better understand how regenerating muscle fibers become innervated in adult animals. To induce muscle regeneration, individual identified muscle fibers in a mouse were damaged with a laser focused through a microscope. The muscle fiber that degenerated and the muscle fiber that was formed in its place were followed by viewing the same site repeatedly over a...

Skeletal muscles are readily characterized by their location within the body and by the number and composition of their constituent muscle fibers. Here, we characterize a mutation that causes a severe reduction in the number of fibers comprising the tergal depressor of the trochanter muscle (TDT, or jump muscle), which functions in the escape response of the Drosophila adult. The wild-type TDT ...

Muscle sensory axons induce the development of specialized intrafusal muscle fibers in muscle spindles during development, but the role that the intrafusal fibers may play in the development of the central projections of these Ia sensory axons is unclear. In the present study, we assessed the influence of intrafusal fibers in muscle spindles on the formation of monosynaptic connections between ...

The cellular and subcellular responses related to the survival or destruction and subsequent regeneration of muscle fibers within the freely grafted extensor digitorum longus muscle of the rat were examined by light and electron microscopy. A small number of fibers at the periphery of the grafts survived the initial ischemia but underwent denervation changes and accumulated lipid deposits. The ...