# IONIC PROPERTIES OF SKELETAL MUSCLE MEMBRANES

> **NIH NIH R01** · UNIVERSITY OF ROCHESTER · 1990 · $150,452

## Abstract

The membrane mechanisms resulting in the movements of K+ and
Cl- in normal skeletal muscle fibers of the frog are being studied.
These two ions account for most of the membrane conductance in
quiescent muscle fibers.  In resting muscle the major passive
pathway for K+ movement is the inward rectifier channel while
the major pathway for Cl- movement is the external pH
dependent Cl- channel.

The pH dependent chloride channels in frog skeletal muscle
appear to be principally located in the external surface of muscle
cells with few such channels present in the membranes lining the
transverse tubular system.  Transmembrane chloride fluxes
increase markedly when external pH is increased from 5.0 to 10.0
with a midpoint at about pH 6.8.  The effects of external chloride
concentration, membrane potential, and group specific chemical
reagents on the pH dependence of chloride movements will be
examined.  In addition, the effects on Cl- movements of inorganic
anions of the lyotropic series and various aromatic carboxylic
acids will be studied at various external pHs, (Cl-)o, and
membrane potentials and after chemical modification.

The inward rectifier channels are located in the membranes
covering the external surface of muscle cells as well as those
lining the transverse tubular system.  They provide the principal
control for steady state membrane potential and, indirectly, other
electrical properties of striated muscle under resting conditions.
The rectifier channels will be studied in (1) whole sartorius
muscles and in (2) single fibers under controlled membrane
potentials where both the internal and external concentrations of
different ions can be varied.  The effects of other ions, such as
Rb+ and Tl+, which both activate and inhibit potassium
movements through the rectifier as well as moving through the
rectifier channels themselves, will be studied.  The modifications
produced by various agents (i.e.  quaternary onium ions) on this
channel system will also be explored.

The properties of the K+ inward rectifier are among the factors
involved in hypotension and skeletal muscle weakness associated
with hyperkalemia.  Alteration of membrane conductance to
chloride ions is one of the factors involved in some myotonias.

## Key facts

- **NIH application ID:** 3156109
- **Project number:** 5R01AR031814-08
- **Recipient organization:** UNIVERSITY OF ROCHESTER
- **SAM.gov UEI:** F27KDXZMF9Y8
- **Principal Investigator:** PAUL HOROWICZ
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $150,452
- **Award type:** 5
- **Project period:** 1988-02-01 → 1993-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3156109

## Citation

> US National Institutes of Health, RePORTER application 3156109, IONIC PROPERTIES OF SKELETAL MUSCLE MEMBRANES (5R01AR031814-08). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3156109. Licensed CC0.

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