Possible involvement of ATP-sensitive K+ channels in the relaxant response of dog middle cerebral artery to cromakalim

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Pharmacology and Experimental Therapeutics; (USA)

OSTI ID:6072752

Masuzawa, K; Asano, M; Matsuda, T; Imaizumi, Y; Watanabe, M ^[1]

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1. Nagoya City Univ. Medical School (Japan)

To determine the functions of ATP-sensitive K+ (KATP) channels in cerebral arterial smooth muscle, the effects of cromakalim, an opener of these channels, on tension and 86Rb efflux were investigated in endothelium-removed strips of dog middle cerebral arteries (MCAs). Cromakalim relaxed the strips that were precontracted with 20.9 mM K+ with a small maximum response. The relaxant responses to cromakalim were competitively antagonized by glibenclamide, a blocker of KATP channels. In strips precontracted with 65.9 mM K+, cromakalim failed to relax the strips. The addition of cromakalim to a resting strip caused a dose-dependent relaxation. In the resting strips of MCAs preloaded with 86Rb, cromakalim did not increase the 86Rb efflux. With 42K as the tracer ion, cromakalim still had no effect on the efflux from the resting strips. On the other hand, cromakalim increased the 86Rb and 42K efflux from the strips of dog coronary arteries (CAs). In 20.9 mM K(+)-contracted strips of MCAs, cromakalim significantly decreased the 86Rb efflux. However, after the inactivation of Ca(++)-activated K+ channels by the addition of 1 x 10(-7) M nifedipine to the 20.9 mM K(+)-contracted strips of MCAs, cromakalim produced a small but significant increase in the 86Rb efflux. Similarly, when the resting strips of MCAs were placed in the Ca(++)-free 12 mM-Mg(+)+ solution, cromakalim increased the 86Rb efflux. In 65.9 mM K(+)-contracted strips, cromakalim increased the 86Rb efflux from both arteries. However, the extent of the increase in 86Rb efflux was significantly smaller in the MCA than in the CA.

• OSTI ID: 6072752
• Journal Information: Journal of Pharmacology and Experimental Therapeutics; (USA), Vol. 255:2; ISSN 0022-3565
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
PERMEABILITY
POTASSIUM COMPOUNDS
MEMBRANE TRANSPORT
VASODILATORS
BIOLOGICAL EFFECTS
ARTERIES
ATP
CEREBRAL CORTEX
DOGS
DOSE-RESPONSE RELATIONSHIPS
ENDOTHELIUM
MUSCLES
PORINS
POTASSIUM 42
RUBIDIUM 86
TRACER TECHNIQUES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
BRAIN
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CEREBRUM
DAYS LIVING RADIOISOTOPES
DRUGS
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MINUTES LIVING RADIOISOTOPES
NERVOUS SYSTEM
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
POTASSIUM ISOTOPES
PROTEINS
RADIOISOTOPES
RUBIDIUM ISOTOPES
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques