Comparison of effects of cromakalim and pinacidil on mechanical activity and 86Rb efflux in dog coronary arteries

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Pharmacology and Experimental Therapeutics; (USA)

OSTI ID:7016512

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

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1. Nagoya City Univ. Medical School (Japan)

Effects of two K+ channel openers, cromakalim and pinacidil, on mechanical activity and on 86Rb efflux were compared in strips of dog coronary arteries. Cromakalim and pinacidil produced the relaxation in 20.9 mM K(+)-contracted strips with a pD2 of 6.53 and 5.95, respectively. In 65.9 mM K(+)-contracted strips, high concentrations of pinacidil, but not cromakalim, produced relaxation. Ca+(+)-induced contractions in 80 mM K(+)-depolarized strips were also inhibited by pinacidil but not by cromakalim. Glibenclamide, a blocker of ATP-regulated K+ (KATP) channels, competitively antagonized the relaxant responses to cromakalim with a pA2 value of 7.62. However, the antagonism by glibenclamide of the relaxant responses to pinacidil was not a typical competitive type, suggesting the contribution of other effects than the KATP channel opening activity to the relaxant effects of pinacidil. In resting strips preloaded with 86Rb, cromakalim and pinacidil increased the basal 86Rb efflux in a dose-dependent manner. The increase in the 86Rb efflux induced by cromakalim was greater than that by pinacidil. When the effects of cromakalim and pinacidil on the 86Rb efflux were determined in the 20.9 or 65.9 mM K(+)-contracted strips, both drugs increased the 86Rb efflux. Under the same conditions nifedipine, a Ca(+)+ channel blocker, produced the relaxation that is accompanied by the decrease in 86Rb efflux. The increase in the 86Rb efflux induced by cromakalim was much greater than that by pinacidil.

• OSTI ID: 7016512
• Journal Information: Journal of Pharmacology and Experimental Therapeutics; (USA), Vol. 253:2; ISSN 0022-3565
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
POTASSIUM COMPOUNDS
MEMBRANE TRANSPORT
VASODILATORS
BIOLOGICAL EFFECTS
COMPARATIVE EVALUATIONS
CORONARIES
DOGS
DOSE-RESPONSE RELATIONSHIPS
MUSCLES
RUBIDIUM 86
TRACER TECHNIQUES
VASOCONSTRICTION
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
DAYS LIVING RADIOISOTOPES
DRUGS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANS
RADIOISOTOPES
RUBIDIUM ISOTOPES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques