Role of sarcolemma and mitochondria in calcium-dependent control of myometrial relaxation

Journal Article · Thu Feb 20 04:00:00 EST 1986 · Biochemistry (Engl. Transl.); (United States)

OSTI ID:5933392

Kosterin, S A; Bratkova, N F; Kurskii, M D

It was shown by the method of atomic absorption spectrophotometry that the content of tightly bound calcium in bovine myometrial mitochondria and sarcolemma is equal to 160 +/- 10 and 30 +/- 10 ..mu..moles/kg of wet tissue, respectively. The Ca/sup 2 +/-accumulating capacity of the mitochondria (350 nmoles/mg protein) greatly exceeds that of the sarcolemmal vesicles (30 nmoles/mg protein). It was demonstrated using Ca/sup 2 +/-EGTA buffer that the affinity of ionized calcium for the mitochondrial transport system (K/sub m/ = 5.69 ..mu..M) is greater than that for the sarcolemmal Na/sup +/-Ca/sup 2 +/ exchange system of the sarcolemma (K/sub m/ = 30 ..mu..M), but less than that for the Mg/sup 2 +/, ATP-dependent Ca/sup 2 +/-transporting system (K/sub m/ = 0.35 ..mu..M). A kinetic analysis indicated that the calcium pump of the sarcolemma is incapable of providing relaxation of smooth-muscle tissue within a physiologically significant time, whereas the mitochondrial Ca/sup 2 +/-transporting system is capable of this (within 21 sec). However, the contribution of the calcium pump to the regulation of the Ca/sup 2 +/ concentration in myocytes is manifested against a background of Ca/sup 2 +/ accumulation by the mitochondria and is realized at low Ca/sup 2 +/ concentrations in the myoplasm, i.e., at a late stage of relaxation. A mechanism of the calcium-dependent control of myometrial relaxation is proposed.

• Research Organization: A.V. Palladin Institute of Biochemistry, Kiev, USSR
• OSTI ID: 5933392
• Journal Information: Biochemistry (Engl. Transl.); (United States), Journal Name: Biochemistry (Engl. Transl.); (United States) Vol. 50:8; ISSN BIORA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BIOLOGICAL FUNCTIONS
BODY
CALCIUM 45
CALCIUM CHLORIDES
CALCIUM COMPOUNDS
CALCIUM HALIDES
CALCIUM ISOTOPES
CATTLE
CELL CONSTITUENTS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
CONNECTIVE TISSUE
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
DOMESTIC ANIMALS
ENERGY DEPENDENCE
ENZYMES
EVEN-ODD NUCLEI
FEMALE GENITALS
FUNCTIONS
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
ION EXCHANGE
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LABELLING
MAMMALS
MEMBRANE TRANSPORT
MITOCHONDRIA
NUCLEI
ORGANOIDS
ORGANS
OXIDOREDUCTASES
RADIOISOTOPES
RADIONUCLIDE KINETICS
RELAXATION
RETENTION
RUMINANTS
SPECTROPHOTOMETRY
TISSUE DISTRIBUTION
TISSUES
TRACER TECHNIQUES
UTERUS
VERTEBRATES