Differential blockade of agonist- and depolarization-induced sup 45 Ca2+ influx in smooth muscle cells

Journal Article · Sun Oct 01 00:00:00 EDT 1989 · American Journal of Physiology; (USA)

OSTI ID:5161392

Wallnoefer, A C; Cauvin, C; Lategan, T W; Rueegg, U T ^[1]

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1. Preclinical Research, Sandoz Limited, Basel (Switzerland)

ATP stimulated {sup 45}Ca2+ influx in rat aortic smooth muscle cells in a concentration-dependent manner (EC50 = 3.6 +/- 0.5 X 10(-7) M). ADP and GTP were less effective than ATP in stimulating {sup 45}Ca2+ influx; AMP was weakly active and the adenosine agonist 5'-(N-ethyl-carboxamido)-adenosine (NECA) had no effect. ATP gamma S was about equieffective with ATP, whereas alpha,beta-methylene-ATP (APCPP) did not induce {sup 45}Ca2+ influx. Stimulation of {sup 45}Ca2+ influx by ATP was not abolished by the dihydropyridine Ca2+ channel antagonist darodipine (PY 108-068), which completely blocked depolarization-induced {sup 45}Ca2+ influx. Inorganic cations (La3+, Cd2+, Co2+, Ni2+, Mn2+, and Mg2+) were able to inhibit both agonist- and depolarization-induced {sup 45}Ca2+ influx. Cd2+, however, was approximately 20 times more selective in blocking K+-stimulated than agonist-stimulated {sup 45}Ca2+ influx. These data indicate that ATP-stimulated Ca2+ influx in rat aortic smooth muscle cells is resistant to darodipine but is reduced by La3+, Cd2+, and other inorganic blockers of Ca2+ channels.

• OSTI ID: 5161392
• Journal Information: American Journal of Physiology; (USA), Vol. 257; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ATP
BIOCHEMICAL REACTION KINETICS
CALCIUM
MEMBRANE TRANSPORT
AORTA
CALCIUM 45
CATIONS
CELL MEMBRANES
DOSE-RESPONSE RELATIONSHIPS
ENZYME INHIBITORS
ISOTOPE DILUTION
MUSCLES
PORINS
POTASSIUM COMPOUNDS
RATS
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CALCIUM ISOTOPES
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CHARGED PARTICLES
DAYS LIVING RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
METALS
NUCLEI
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
TRACER TECHNIQUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques