# MUSCLE ENERGETICS AND CHEMOMECHANICAL TRANSDUCTION

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 1987 · $169,369

## Abstract

The mechanism by which muscle converts chemical energy in the form of
adenosine triphosphate (ATP) into mechanical energy as work, force and
shortening (chemomechanical transduction) will be studied.  Current
theories of chemomechanical transduction are based on kinetic analyses of
the ATPase of isolated muscle proteins in solution and mechanical
measurements on muscles cells.  These theories require that the rate of ATP
hydrolysis is regulated by how fast the muscle shortens or lengthens and
assume that the rate at which ATP hydrolysis products, inorganic phosphate
(Pi) and adesoine diphosphate (ADP), are released by the crossbridges is
determined by the the force or displacement applied to the crossbridges.
The rate of ATP is hydrolysis by shortening or lengthening mammalian
muscles and whether force or displacement affects the rate of product
release by the crossbridge are not known.  The development of 2-nitro
benzyl derivates of ATP, ADP, and Pi, which can rapidly (greater than 100
s-1) photogenerate ATP, ADP, or Pi allows measurement of the rate of ATP
hydrolysis and, by employing transient kinetic techniques, the rate
constants for Pi and ADP release and binding in single glycerinated muscle
fibers.  The studies described in this application are designed to
experimentally measure the influence velocity of shortening and lengthening
have on the rate of ATP hydrolysis, the efficiency of work performance, and
product release rate constants in single glycerinated muscle fibers.  In
theories of contractile regulation, the force development and actomyosin
ATPase rate are controlled by the sarcoplasmic calcium concentration by
either a steric blocking mechanism or modulation of the rate of Pi release
from the actomyosin-products complex.  Both mechanisms predict that the
isometric force and ATPase rate should rise in parallel with increases in
the sarcoplasmic calcium concentration.  This hypothesis, as well as the
effect of calcium concentration on the rate of Pi release from the
crossbridge, will be examined in glycerinated muscle fibers are proposed in
which the minimum distance a crossbridge can remain attached to the thin.
These simultaneous measurements of mechanical behavior and chemical change
in a system whose structural integrity and mechanical restrains are
preserved and under direct experimental control, permits rigorous testing
of current theories of contraction.

## Key facts

- **NIH application ID:** 3155940
- **Project number:** 2R01AR030988-06
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **SAM.gov UEI:** RN64EPNH8JC6
- **Principal Investigator:** EARL E HOMSHER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $169,369
- **Award type:** 2
- **Project period:** 1982-05-01 → 1992-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3155940

## Citation

> US National Institutes of Health, RePORTER application 3155940, MUSCLE ENERGETICS AND CHEMOMECHANICAL TRANSDUCTION (2R01AR030988-06). Retrieved via MORVS 2026-10-24 from https://api.morvs.ai/grant/nih/3155940. Licensed CC0.

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