# ELECTRICAL AND CONTRACTILE PROPERTIES OF MUSCLE

> **NIH NIH R01** · YALE UNIVERSITY · 1991 · $396,344

## Abstract

In vertebrate twitch muscle fibers, contraction is normally activated by
a depolarization of the membranes of the transverse tubular system. This
leads to a movement of Ca from inside the sarcoplasmic reticulum (SR) into
myoplasm where it can bind to the Ca-regulatory sites on troponin so that
contraction can occur. The longterm objectives of the research proposed in
this application are to understand (A) how Ca movement from the SR into
myoplasm is regulated by the potential difference across the membranes of
the transverse tubular system and (B) what happens to the Ca after it is
released into the myoplasm. The experiments will be carried out on frog cut
twitch fibers mounted in a double Vaseline-gap chamber. Changes in
myoplasmic Ca will be measured with Ca indicators after either
action-potential stimulation or voltage-clamp depolarization. Currents from
intramembranous charge movement, which are thought to play a role in the
regulation of SR Ca release by the tubular membranes, will be measured with
the voltage-clamp method.

The specific aims are:

1. To measure Ca release from the SR of cut muscle fibers in which free
[Ca] is buffered to a nearly constant level by a large concentration of a
high affinity Ca indicator.

2. To measure the reuptake of Ca by the SR, after its release, in cut
muscle fibers in which free [Ca] is buffered to a nearly constant level by
a large concentration of a high affinity Ca indicator.

3. To measure charge movement in cut muscle fibers in which free [Ca] is
buffered to a nearly constant level by a large concentration of a high
affinity Ca indicator or buffer.

4. To simultaneously measure and compare charge movement, or some component
of it, and SR Ca release in cut muscle fibers in which free [Ca] is
buffered to a nearly constant level by a large concentration of a high
affinity Ca indicator.

5. To simultaneously measure and compare charge movement, or some component
of it, and SR Ca release in cut muscle fibers under more normal
physiological conditions in which free [Ca] is not heavily buffered by
extrinsic Ca buffers.

## Key facts

- **NIH application ID:** 3158263
- **Project number:** 2R01AR037643-24
- **Recipient organization:** YALE UNIVERSITY
- **SAM.gov UEI:** FL6GV84CKN57
- **Principal Investigator:** WILLIAM K CHANDLER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1991
- **Award amount:** $396,344
- **Award type:** 2
- **Project period:** 1991-01-20 → 1994-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3158263

## Citation

> US National Institutes of Health, RePORTER application 3158263, ELECTRICAL AND CONTRACTILE PROPERTIES OF MUSCLE (2R01AR037643-24). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3158263. Licensed CC0.

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