Glycerol treatment in mammalian skeletal muscle

Abstract

(1) The effects of glycerol-treatment on the ultrastructure, tension, and electrical properties of rat sternomastoid muscle fibers are described. (2) The effect upon the ultrastructure of fibers differed from that previously reported for amphibian fibers, in that the sarcoplasmic reticulum, as well as the T-system, was disrupted. (3) Tension (tension (tetanus and K-contracture) was abolished when preparations were returned to normal Krebs after exposure to a glycerol-Krebs solution (exposure periods were 1 hr in 200--350 mM-glycerol or 10--60 min in 350 mM-glycerol), although fibers had normal resting membrane potentials and action potentials. (4) Fibers treated for 1 hr with 350 mM-glycerol were detubulated when returned to normal Krebs. Specific membrane capacity was reduced and exogenous horseradish peroxidase (HRP) did not penetrate the T-system. (5) Fibers were not detubulated after treatment for 1 hr with 200 to 300 mM-glycerol or after treatment for 10 to 30 min with 350 mM glycerol. Specific membrane capacity and resistance were normal and HRP entered the T-system. (6) Ultrastructural disruption of the triad junction became progressively more extensive with increasing glycerol concentration used and may be responsible for uncoupling.

Ca2+ Influx via the Na+/Ca2+ Exchanger Is Enhanced in Malignant Hyperthermia Skeletal Muscle

“…These pharmacological treatments also potentiate the observed increase in [Ca 2ϩ ] r in swine muscle fibers from both genotypes (data not shown), suggesting that plasma-membrane Ca ] r in both genotypes. Previous work has shown that glycerol treatment disrupts excitation-contraction coupling in skeletal muscle by disconnection of the transverse tubular system from the extracellular space (32,33). Here we show that detubulation of MHN and MHS swine fibers induces a small increase in [Ca 2ϩ ] r in both types of muscle fibers (16% MHN and 10% MHS, respectively).…”

“…Glycerol Treatment-It is well established that glycerol treatment can be used to osmotically disrupt the transverse tubules in skeletal muscle (32,33). Briefly, intact MHN and MHS swine muscle fibers were incubated in 350 mM glycerol solution for 1 h, and then returned to normal swine physiologic solution (32).…”

“…Briefly, intact MHN and MHS swine muscle fibers were incubated in 350 mM glycerol solution for 1 h, and then returned to normal swine physiologic solution (32). Destruction of the transverse tubular system occurs not in the glycerol solution itself, but occurs only after the muscle fibers have been returned to normal physiologic solution due to the osmotic shock produced by glycerol withdrawal.…”

“…Destruction of the transverse tubular system occurs not in the glycerol solution itself, but occurs only after the muscle fibers have been returned to normal physiologic solution due to the osmotic shock produced by glycerol withdrawal. The osmotic shock produces a physical and functional dissociation of the t-tubules from the surface membrane (detubulation) (32,33).…”

Contraction of rat skeletal muscle after glycerol treatments.

“…At the higher temperature, twitch and tetanic tension were reduced 90° and 86 from control values of 43.0 ± 1.8 (n = 3) and 232.7 + 9.6 mN (n =3) respectively. DAVEY et al (1980) found that glycerol treatment abolished twitches and potassium contractures in a fast-twitch skeletal muscle. Experiments were carried out on four extensor digitorum longus muscles (EDL).…”