Evidence of a role for calmodulin in the regulation of calcium release from skeletal muscle sarcoplasmic reticulum

Journal Article · Tue Jan 14 04:00:00 EST 1986 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00349a034· OSTI ID:5739207

Meissner, G

The effect of calmodulin and calmodulin inhibitors on the Ca2+ release channel of heavy skeletal muscle sarcoplasmic reticulum (SR) vesicles was investigated. SR vesicles were passively loaded with 45Ca2+ in the presence of calmodulin and its inhibitors, followed by measurement of 45Ca2+ release rates by means of a rapid-quench-Millipore filtration method. Calmodulin at a concentration of 2-10 microM reduced 45Ca2+ efflux rates from passively loaded vesicles by a factor of 2-3 in media containing 10(-6)-10(-3) M Ca2+. At 10(-9) M Ca2+, calmodulin was without effect. 45Ca2+ release rates were varied 1000-fold (k1 approximately equal to 0.1-100 s-1) by using 10(-5) M Ca2+ with either Mg2+ or the ATP analogue adenosine 5'-(beta,gamma-methylenetriphosphate) in the release medium. In all instances, a similar 2-3-fold reduction in release rates was observed. At 10(-5) M Ca2+, 45Ca2+ release was half-maximally inhibited by about 2 X 10(-7) M calmodulin, and this inhibition was reversible. Heavy SR vesicle fractions contained 0.1-02 micrograms of endogenous calmodulin/mg of vesicle protein. However, the calmodulin inhibitors trifluoperazine, calmidazolium, and compound 48/80 were without significant effect on 45Ca2+ release at concentrations which inhibit calmodulin-mediated reactions in other systems. Studies with actively loaded vesicles also suggested that heavy SR vesicles contain a Ca2+ permeation system that is inhibited by calmodulin.

• Research Organization: Univ. of North Carolina, Chapel Hill
• OSTI ID: 5739207
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 1; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
CATTLE
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELEMENTS
EVEN-ODD NUCLEI
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
INHIBITION
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAGNESIUM
MAMMALS
MEMBRANE TRANSPORT
METALS
MUSCLES
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
RABBITS
RADIOISOTOPES
RUMINANTS
SARCOPLASMIC RETICULUM
TRACER TECHNIQUES
VERTEBRATES